Science topic

Optics and Photonics - Science topic

Optics and Photonics are a specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.
Questions related to Optics and Photonics
  • asked a question related to Optics and Photonics
Question
5 answers
I use Fujikura CT-30 cleaver for PCF cleaving to use for supercontinuum generation. Initially, it seems like working fine as I could get high coupling efficiency (70-80%) in the 3.2um core of PCF. However, after some time (several hours) I notice that coupling efficiency decreases drastically and when I inspect the PCF endface with an IRscope, I could see a bright shine on the PCF end facet, which is maybe an indication that the end face is damaged. Also, I want to mention that the setup is well protected from dust and there is no chance of dusting contaminating the fiber facet.
Please suggest what should be done to get an optimal cleave, shall I use a different cleaver (pls suggest one) or there are other things to consider.
Thanks
Relevant answer
Answer
Supercontinuum generation by short pulse with high power that lead to traction or fusion soliton.
  • asked a question related to Optics and Photonics
Question
3 answers
As you know, the refractive index of a specific material is a function of wavelength. This phenomenon is called dispersion. The Sellmeier equation is an empirical formula for calculating the wavelength-dependent refractive index of a particular transparent medium. For common optical material, the refractive index is computed with 6 sellmeier coefficients (B1,2,3 and C1,2,3). Unfortunately I couldn’t find these coefficients for CR-39, or allyl diglycol carbonate (ADC), in databases that are available in literature (even in Schott Glass and Ohara catalogues).
Relevant answer
Answer
I am humbly suggest this video on how to fit Sellmeier function using Origin 2019 software
  • asked a question related to Optics and Photonics
Question
2 answers
Hi there!
I have a question:
What is the best photonic network on chip simulator which has a good manuals and learning and community?
best
Yasin Asadi
Relevant answer
Answer
Hi Yasin
I think the best option is Lumerical Interconnect. In this module, you can either define your own device or just use the predefined elements like MZIs, ring resonators, modulators, and detectors to build your own optical network. It can integrate with KLayout for chip design and test, and also provides a reliable simulation results based on TMM or S-matrix method. Besides, the Lumerical "knowledge base" website is available for all users where you can either use it as a learning tool or debugging your simulation procedure and coding.
  • asked a question related to Optics and Photonics
Question
4 answers
Here you can talk and share your idea and experiences on network on chip simulators in any fields like Wire, Wireless, 2D, 3D, Photonic, etc.
feel free to ask questions and share ideas.
what is the best simulator in this field and what makes it better than others?
Relevant answer
Answer
Check the link provided below, where you can see a list of simulators for NoC.
  • asked a question related to Optics and Photonics
Question
5 answers
Hello everyone, I need some channel models MATLAB code to simulate my Underwater Visible Light Communication algorithm. If anybody has some models then please provide. thank you.
Relevant answer
Answer
Hello sir,
please check our paper Statistical Studies Using Goodness-of-Fit
Techniques With Dynamic Underwater Visible
Light Communication Channel Modeling,
Hopefully, it will cover your needs.
Also, If you need anything related to codes, send me an email at afikky@ucsc.edu
  • asked a question related to Optics and Photonics
Question
4 answers
when we introduce a defect layer in the middle of the photonic crystal (binary, ternary, or any other structure) a resonant mode appears somewhere within the photonic bandgap. I have noticed that the FWHM of these resonant modes decreases as the number of cells in the photonic crystal increase! Anybody knows why!
Relevant answer
Answer
nice answer dear
  • asked a question related to Optics and Photonics
Question
3 answers
Hi, I am new to this and trying to design a waveguide at 850 nm. So I simulated the structure in Lumerical for different core sizes. These three graphs(attached) are the results I got for mode 1( which I think is a fundamental mode). How do I conclude the result, should I choose the core size for which TE fraction is 1? How TE/TM ratio and other parameters will affect the optimization process? Also I'd like to know how optimization process will differ for single mode.
Thanks for reading. I really appreciate any suggestion.
Relevant answer
Answer
There is not always a straightforward answer and the decisions you want to take depends on various constraints (Is it purely theoretical or do you plan something experimental as well; Thickness avaiable in the Fab you intend to use; Quality of materials; material losses; safety margins, etc. etc.).
For practical issues of simulation (in particular in lumerical) and decision making, I can highly recommend the book by Chrostowski and Hochberg (silicon photonics design: from devices to systems); No matter if you work with silicon photonics or any other material, the decision making and design principles are the same.
If you intend a real experiment, it is very common that you actually fabricate not just one waveguide, but actually fabricate a whole series of thicknesses or width (or whatever paramterers you have freedom of choice) to get a real feel for "the right" waveguide for your application. Usually simulation is one thing, but in reality sometimes the waveguide, which is according to the simulation the "best", in reality sometimes isn't.
Regards,
Michael
  • asked a question related to Optics and Photonics
Question
2 answers
What are the advantages of using SiO2 substrate over Si substrate for monolayer graphene in photonics?
Relevant answer
Answer
Dear
Behnam Farid
Thanks for your complete answer.
In fact, I thought about the hot electron injection to the substrate.
As we're expecting localized or propagating plasmons in graphene, isn't it possible to have electron leakage from the graphene to high doped substrates? Instead, SiO2 or other insulators offer electrostatic charge transfer, which may facilitates the graphene-graphene hybridization in periodic structures like 1D graphene ribbons. Is this a valid claim?
  • asked a question related to Optics and Photonics
Question
7 answers
Hello. I am currently working on Ansys Lumerical software for design a photonic structure and understand how light behaves when adding layers... Any tutorial (besides the website) for helping?
Relevant answer
Answer
Sara Resende i do agree with Ebrahim E. Elsayed and the link shows the detais about the photonics and also Aydin Amini as given the perfect reply.
However LED behaviour is dynamic and we need to understand this factor along with LED Deisgn Tradeoffs
  • asked a question related to Optics and Photonics
Question
1 answer
I use the formula in this article to calculate its topological invariants, but I always make mistakes. Is there anyone who is willing to solve my problem..
The left and right vectors meet the conditions in the article. For the continuous wave function problem, I also use Wilson loop method to avoid it, but I always make mistakes.
Maybe the problem is in the discontinuous wave function. How to solve the problem of wave function discontinuity in non Hermitian system?
Relevant answer
Answer
Follow up
  • asked a question related to Optics and Photonics
Question
3 answers
Both for 1330 nm and 1550 nm
Relevant answer
Answer
Follow up
  • asked a question related to Optics and Photonics
Question
1 answer
Which one is better regarding loss, stress, roughness for photonic and optical applications at 1330 nm and 1550 nm wavelengths.
Relevant answer
Answer
Follow-up
  • asked a question related to Optics and Photonics
Question
2 answers
I am currently trying to simulate a THz metastructure in CST studio using the frequency domain solver. I would like to know if it possible to change the field strength of the incident radiation. TIA.
Relevant answer
Answer
Jihong Zhang Thank you for the answer.The material I am trying to simulate is non-linear in nature, the optical constants are strongly dependent on the field. Which is why I want to alter the excitation strength. I found out that one can feed a custom input signal from the new signal tab under the simulation tab.
  • asked a question related to Optics and Photonics
Question
1 answer
As a result from the collaboration with Fabrice Raineri at Centre de Nanosciences et Nanotechnologies, Sylvain Combrié and I are proud to introduce the first Optical Parametric Oscillator made of a 20 by 5 microns photonic crystal cavity. With a power threshold as low as 50microWatt and a combined slope efficiency approaching 50%, it might stimulate new results in the field of integrated photonics, including quantum technologies. You can find details here:
Marty, G., Combrié, S., Raineri, F. et al. Photonic crystal optical parametric oscillator. Nat. Photonics (2020)
Relevant answer
Answer
Dear Alfredo De Rossi Thank you for your information.
  • asked a question related to Optics and Photonics
Question
2 answers
“The interaction of a field with a thin scattering layer corresponds to multiplication with a diagonal matrix“
Original from:Wetzstein, Gordon, et al. "Inference in artificial intelligence with deep optics and photonics." Nature 588.7836 (2020): 39-47.
Relevant answer
Xiaohui Zhu , here is a short answer. For details, I suggest to read the book: "Introduction to Fourier Optics" by Goodman, J. W. (Roberts and Co, 2005), chapter 5 and Appendix B.
Answer:
A scattering layer is typically composed of an optically dense material, with a refractive index significantly different than the one of air, and then the propagation velocity of an optical disturbance is less than the velocity in air.
Since the layer is thin, the sole effect of it is to shift the phase of waves when they are passing through it. Such a phase shift, as compared to air, results in a phase delay
\Delta \phi = k(n-1)d
where n is the index of refraction of the layer's material, d its thickness.
Transformations involving phase shifts are associated with the diagonal elements of the transformation matrix.
  • asked a question related to Optics and Photonics
Question
3 answers
What effect does the height of the dielectric rods on the photonic crystal (three dimension) have on the photonic band gap? (Could height cause high displacement in the photonic band gap range)
What effect does increasing the radius of the rods in three-dimensional mode have on the band gap gap?
Relevant answer
Answer
Thanks for sharing this discussion to me. However, my research area is one-dimensional photonic crystals. So I don't know too much about three-dimensional photonic crystals. I try to answer this question below.
For two-dimensional case (the height of the dielectric rod is infinite), you can obtain photonic band gap by calculating or simulating the band structure. As the height of the dielectric rod becomes finite, the photonic crystal actually becomes photonic crystal slab (with finite height). Therefore, the photonic crystal slab also possesses guided mode. Compared with two-dimensional photonic crystal with infinite height, the band structure of photonic crystal slab with finite height will become quite complex. You can refer the book about photonic crystal by John.
  • asked a question related to Optics and Photonics
Question
5 answers
Hello
Why using a radius with 5 μm in the waveguide at photonic integrated circuits while a radius with 7 μm has minimum loss?
Relevant answer
Answer
Dear Fatimah,
As colleagues wrote above there are several possible reasons for that ( if you asked about a cross-section of a waveguide) such as:
1) Amount of modes (normally it should be single-mode to avoid beats between modes and optical losses for high order modes due to scattering on walls what is explained lower factor of mode confinement ),
2) Propagated polarizations (it depends on requirements for PIC as well as technology peculiarities),
3) Dispersion engineering (that is the crucial thing for success if there are tasks in microcombs in optical resonators),
4) Stresses in waveguide films that appear during sputtering/oxidation/deposition.
If you wrote about bending radius then the answers of Malcolm White and Mursal Ayub Hamdani described it.
  • asked a question related to Optics and Photonics
Question
3 answers
Dear All
I lead a special issue in Photonics (SCIE indexed; Impact Factor 2.140).
The aim and scope of the special issue is "Photonic devices and systems". I would like to invite you to submit a paper for this special issue. Your outstanding participation will be interesting for many readers. Thank you!
Cheng-Yang Liu
Associate Professor
Department of Biomedical Engineering
National Yang-Ming University, Taiwan
Relevant answer
Answer
Now, this Special Issue offers special discount or waivers. Please contact me.
  • asked a question related to Optics and Photonics
Question
6 answers
Hello Dear Researchers, I am confused about the Difference between Second-harmonic generation and Two-photon absorption? Can anyone describe the two phenomena briefly in the physical picture? What is the difference in measuring them?? Thanks a lot.
#Photonics #Optics #Physics #Nonlinear Optics
Relevant answer
Answer
Milan's answer formally covers the difference in perturbative orders between the two effects. However, it is worth noting that 2PA leaves the material in an excited state from which it often relaxes internally before decaying radiatively, meaning it can deposit some energy in the absorbers. Also, the emission resulting from 2PA is incoherent and is emitted sometime after the absorption.
SHG, on the other hand, is a virtual process (classically it can be envisioned as coming from the coherent excitation the material's polarization oscillating at twice the frequency of the incident fundamental wave) and does not deposit energy into the medium. Because it is a coherent process, phenomena like phase matching matter and it only occurs during the time the incident wave is present in the medium.
  • asked a question related to Optics and Photonics
Question
4 answers
Hello,
I have started reading about photonics circuits, and most papers I read about this devices I noticed that they are designed to operate single mode instead of multi mode. But I haven't been able to find why is this the case?
Can someone explain me or refer me to a paper where this is explained?
Relevant answer
Answer
Good question
  • asked a question related to Optics and Photonics
Question
2 answers
I have tried to regenerate the result from drude-lorentz model in the article "Ultra-broadband THz time-domain spectroscopy of common polymers using THz air photonics". The dielectric number of PA6(figure 2 below). my result is very similar to the results but are not equal. I have multiplied both oscillator strength and resonance frequency in 2*pi but the damping coefficient has not been multiplied.
in both COMSOL and MATLAB my results are similar but are different from the article. I think the problem must be about the coefficients in table 2 of the paper.
Relevant answer
Answer
Hello! You can obtain dielectric function from the article using grafula software.
  • asked a question related to Optics and Photonics
Question
2 answers
I am trying to model a photovoltaic device using AMPS-1D software. But once I am submitting it to queue, it remains there for infinite amount of time without giving the result.
I couldnt understand what is the problem. Kindly please help me out.
Thank you in advance.
Relevant answer
Answer
I am facing the same problem sir. Can you please help me out regarding this issue?TIA
  • asked a question related to Optics and Photonics
Question
5 answers
Dear Colleagues,
I'm studying the optical limiting effect in organic material due to reverse saturation absorption. As we know, in reverse saturation absorption, the transmission coefficient decreases as the intensity increases, or the absorption coefficient increases as the intensity increases, resulting in power loss. So, when we increase the laser power to a threshold P0, there are two competing processes: the increase in input power and the power loss due to reverse saturation absorption. If these two processes are in equilibrium, the optical limit curve is horizontal (as in the attached pictures.) However, if the amount of lost power is greater than the increase in input power, the curve must go down at P0. Why in the paper on optical limiting don’t we  see such cases?
Thank you and hoping for your insightful response.      
Relevant answer
Answer
The absorption coefficient of a material showing RSA will increase when the input optical fluence is increased. However, the processes underlying RSA (mostly excited state absorption in organic molecules) do not result in the absorption of more light than what is fed into it. Therefore, the scenario you envisage will not happen.
  • asked a question related to Optics and Photonics
Question
9 answers
Hello! Colleagues, what resource do you use to monitor conferences on fiber optics and photonics?
Relevant answer
Answer
There's a conference in 2021 that is good when it starts telling you
  • asked a question related to Optics and Photonics
Question
4 answers
I was trying to simulate a dielectric slab with epsilon=4 and Miu=1 and conductivity =0. My objective is simply to get reflected and transmitted spectra following the Fresnel’s equation for normal incidence. The simulation setup is as follows,
solver: Time domain
boundary condition: along x and y open boundary, at zmax open and at zmin open(add space)
port: waveguide port 1 at Zmin (this port is in the background medium, which is normal or air) and waveguide port 2 at Zmax (on the dielectric end)
Simulation range in wavelength: 1.45 to 1.65.
Wave generating at port1 incidents at the dielectric from the normal/ air medium.
post processing: optical; calculate reflectance, transmittance, absorbance.
Result: absorbance is between 0.9 to 0.93 while reflectance and transmittance are very small.
I can‘t understand why absorbance is so high as the conductivity of the dielectric is zero.
please help me.
Relevant answer
Answer
Dear Susovan, how did you resolve this issue? What changes did you make? Also, instead of open boundary at x and y, if I use TE and TM wave, will it make any changes to the result?
Thanks in advance.
  • asked a question related to Optics and Photonics
Question
3 answers
BER analyzer parameters meaning.
Relevant answer
Answer
The reliability of data transmission characterizes the probability of getting a distortion for the transmitted data bit. This indicator is often referred to as the Bit Error Rate (BER). The BER value for communication channels without additional means of error protection is 10-4 — 10-6, in optical fiber — 10-9. A ber value of 10-4 indicates that on average, one bit is distorted out of 10,000 bits. The q-factor of the receiving system Q is determined from the expression:
Q = GA/TC,
or, in logarithmic form:
Q[dB] = GA[dB] - 10lgTC[x].
It is the q-factor of the receiving system that determines the signal-to-noise ratio (C/N) at the output of the low-noise Converter (LNC or LNB). It is important to note that the final C/N value does not depend on the LNC gain.
  • asked a question related to Optics and Photonics
Question
14 answers
I want to synchronize two lasers,but one of them has a large intrinsic jitter (Nd:YAG) which is troublesome.
I want some easy ways to reduce that jitter below ps.
I would like either know if injection seeding can reduce this jitter?how?how much jitter reduce will I have(approximately)?
If some one can give me some helpful reference,it would be so nice.
Thanks so much for reading or answering.
Sepideh Ghaffari
Relevant answer
Answer
Jitter of the laser is determined by the noise. There are several factors that affect noise. The noise of the pump power of the laser. If You use an led or laser diode for pumping, then you need to stabilize their current. Also, low noise is provided by stabilizing the temperature of the active medium. The use of frequency and spatial filters plays an important role in stabilization. For better stabilization, various feedback systems can be used, such as phase-locked frequency tuning.
  • asked a question related to Optics and Photonics
Question
3 answers
How to measure the photonic efficiency of a photoanode in the PEC system?
Relevant answer
Answer
You can measure Incident-photon-to-current-conversion-efficiency (IPCE) and from this you will get photonic efficiency.
  • asked a question related to Optics and Photonics
Question
3 answers
Has anyone worked with .vws Till Photonic image files in python? Are there libraries or other ways to extract TIFF images from them directly in the script?
Relevant answer
  • asked a question related to Optics and Photonics
Question
1 answer
Hi ! Good Evening to all :)
As of Im doing my research in photonic studies particularly in study of Optical Microring Resonator of 2D implementation by using the COMSOL Multiphysics 5.5 , I might wanna seek for opinion regarding certain of my result , is it I'm doing it the correct way to design it ? or is it im approaching the correct way to design it ?
Thanks ! :)
Relevant answer
Answer
Hi Syafiq! How are you doing? Have you done your research?
As for 2D simulation of MRR. The first question is, did you use the effective index method for collapsing the height of the waveguide? If no, you would not get proper results for the spectral response. If you are going to do 2D simulations you would need to use EIM or other ways to include the dispersion of a structure. You can find a good explanation of EIM for instance in the book "Computational photonics an introduction with MATLAB" by Marek S.
My opinion is Comsol is not convenient software for simulation of MRR or CROW or SCISSOR. I would recommend you to implement the transfer matrix method (TMM) on MATLAB to simulate single rings or cascaded rings (You can find information about it in the book "Integrated ring resonators" the compendium by D.G. Rabus) or whatever you want. TMM is much faster than Comsol based on FEM. Also when you use TMM material dispersion is directly included in the simulation, you do not have to use any approximation for the calculation of propagation constant, there is a possibility to include losses sources into a simulation.
Steps for TMM sim:
1) Specify waveguide cross-section and materials properties,
2) Find effective indices or propagation constants for each wavelength you used (it could be done by any Mode solver including Comsol) and save it in a text file,
3) Specify MRR structure,
4) Do TMM simulation.
Wish you success and have a good time :)
  • asked a question related to Optics and Photonics
Question
11 answers
Thanks.
Relevant answer
Answer
My quasi D-Shaped fiber is this according to the paper i follow for its design but i need this kind of result which i attached in the second screen shot. Please, some one help me in troubleshooting the problem?
  • asked a question related to Optics and Photonics
Question
123 answers
The very common experiment in optics to demonstrate that light behaves same as the wave is single-slit diffraction.
If we assume that the thickness of the barriers is 0.1 mm, then the length of a slot along the optical axis will be a long route as a green photon will measure it nearly two hundred times larger than its own size.
Now the question is how the photon behaves along with that long route? Does it behave as a particle or wave? If the exit of the slot or a pinhole is causing photon behaves as a wave then why the entrance wouldn't do that? And if we accept that photon behaves like a wave as it enters the single slit or the pinhole, then formally we should apply the Fresnel diffraction equation from the entry of the slot that will lead us to nowhere.
In my opinion, wave-particle duality is leading us solely to some useful approximation but it doesn't talk about reality, as it cannot explain a sort of experiments that unfortunately have been ignored or left behind such as the glory of the shadow, and also the stretching the shadows when they meet each other and so on.
For sure, wave-particle duality is not the end of science and for sure five hundred years later people will not consider the existence as do we do now the same as us that we don't see the things same as our ancestors, so we should be open-minded to be able to open the new horizons.
Relevant answer
Answer
Natalia S Duxbury > “Particle is a real physical object. But what is the wave made of???? Wave function is a mathematical construction”.
Very well said, could not agree more! Theoretical physics for the last (more than) hundred years and specially since Albert Einstein has been an enormous waste in terms of human, natural and economic resources and most of all at the heavy cost of intellectual advance of humanity.
The truth is that formally trained modern theoretical physicists unwittingly follow a philosophy/epistemology (a branch of knowledge that they routinely disparage!), namely Kantianism that has already been discredited long ago by G.W.F. Hegel, the worthy protégé of Kant himself! Modern theoretical “physicists” - following Einstein, are not concerned with knowing objective reality as it is in-itself (ontology), but only with the subjective data (epistemology) they can gather about it; so in actual sense they are trying to understand the working of their own minds, rather than external reality!
The Kantian premise is that objective reality is a messy, chaotic, unwieldy and unknowable thing-in-itself; because it does not follow the pristine precincts of good old commonsense, causality, formal logic and the notions of rationality that have been developed by philosophers starting from the early Greeks. The only thing man can do (Kant posited) is to use his sense perceptions, experimental data, his thought, imagination, fantasy or whatever subjective data he can gather about the objective reality to get on with life. What man at best can do, is to organize this data through his subjective thought, mental tools, logical schemata, mathematical (geometrical, algebraic, symmetry) structures and representations, logical categories, theories etc. to get as much of an “understanding” of objective reality as possible, to deal with it comfortably! A good theory is the one that can cover as much of this data, as well as future possible ones (predictability). This is what is historically known as scholasticism - an endless debate to justify one's subjective choice from various theories; but there is no way to judge who is right, except the power of individual’s proficiency in debating skills!
After the quantum phenomena, the Kantian view of the world became a "self-evident truth" for natural science, if there was any doubt about it before, at all. Theoretical physics led by Albert Einstein embraced the Kantian view of the world whole heartedly and universally and like Moses led an Exodus of the physicists to the promised land of thought and mathematics - his "Castle in the Air", as we see now. According to the Kantian view, objective reality is like an invisible Cheshire cat, which remains unknown, we only deal with the “smile” of the cat that we can perceive through our sense perceptions and process through our subjective mental tools.
From a materialist dialectical world view (that I subscribe to) the quantum phenomena is the most fundamental aspect of objective reality, which abolishes “spacetime” or any other esoteric “fields". All forces are mediated by the exchange of virtual particles. The virtual particles become real particles if enough energy equivalence of their mass is available. Light at all wavelengths are particles that can propagate as wave. Please see the following articles and other related publications, questions and comments in my RG profile:
Ambartsumian, Arp and the Breeding Galaxies:
  • asked a question related to Optics and Photonics
Question
2 answers
Can anyone tell the response time of Kerr-nonlinearity of Silicon and SiO2? And which material have quickest response time?
Relevant answer
Answer
Subhajit Bej Hi Subhajit, that will be great if you could provide some related reference on this topic. Thank you.
  • asked a question related to Optics and Photonics
Question
4 answers
Various colorimetric assays we use are blue/purple/pink/red but not in green shades. Is there any particular reason for this?
Relevant answer
Answer
A colorimeter is a device used in colorimetry that measures the absorbance of particular. Green colour usually get reflected and not absorbed.........may be useful
  • asked a question related to Optics and Photonics
Question
4 answers
Hi. I have designed a photonic crystal waveguide using Rsoft. I can get group velocity figure but I don't know how to see group index figure. Can somebody help me find proper answer?
Relevant answer
Answer
thanks for this question as well as solution
  • asked a question related to Optics and Photonics
Question
3 answers
This question is more in regard to the resonant structures used for sensing applications, namely surface plasmon resonance, photonic crystals and guided-mode resonance based devices, etc which all show a spectral redshift on increasing the refractive index of the top region. I don't remember coming across photonic structures wherein the spectral resonant response blueshifts as we increase the top refractive index. Is it possible for a structure to do so? And if not, why?
Relevant answer
Answer
If you are in the linear optical regime, then the spectral response of the photonic structure is independent of the incident wavelength. The spectral response is the wavelength dependent transmission/reflection,.... of the structure. wavelength-dependent.
  • asked a question related to Optics and Photonics
Question
7 answers
We want to estimate the accuracy of the Hufnagel Valley (HV) model using measured refractive index structure parameter (Cn2(h)) data.
Does anyone know if there there is any Cn2(h) data publicly available somewhere?
Relevant answer
Answer
I think a researcher " Arockia Bazil Raj " published some articles about the topic.
  • asked a question related to Optics and Photonics
Question
7 answers
Dear colleagues,
I am investigating the dependence of the number of diffraction rings on the concentration in third order non-linear organic dyes (due to nonlinear refraction and nonlinear absorption). Prof. Pramodini [1] claims that the number of diffraction rings depends linearly on the concentration. However, Prof. Hussain A Badran [2] assume that the number of rings increases exponentially with respect to the concentration. Our experimental curves on aniline blue and Acid blue 29 showed a linear relationship. However, for Oil Red O, experimental curve is not the straight line and the exponential curve. So, is this relationship linear or exponential?
Thank you and hoping for your insightful response.
1.S. Pramodini, P. Poornesh, Effect of conjugation length on nonlinear optical parameters of anthraquinone dyes investigated using He –Ne laser operating in CW mode, Optics & Laser Technology
2. Badran, Hussain A.; Ali Hassan, Qusay Mohammed; Imran, Abdulameer, A Quantitative Study of the Laser-Induced Ring Pattern and optical limiting From 4-Chloro-3-methoxynitrobenzene solution, Basrah Journal of Agricultural Sciences . 2015, Vol. 41 Issue 2, p51-57. 7p.
Relevant answer
Answer
what is the effect of the increases of the number of rings
  • asked a question related to Optics and Photonics
Question
6 answers
I need the INTERCONNECT software for simulation of photonics integrated circuits.
Relevant answer
Answer
ASAP Software is the most recommended and quite powerful software for Optical interconnect.
  • asked a question related to Optics and Photonics
Question
3 answers
Hi dears
I want to do the absorption of a structure for the wavelength range of 280 to 900 with the desired divisions. For example, I want the wavelength distance in this case to be 0.5 nano, in other words, it returns the absorption information every 0.5 nano.
Lumerical(FDTD) apparently does this for random wavelengths. But I want to get the absorption for wavelengths of 280 to 900 nano, at distances of 0.5 nanometers.
In other words, in the image below, I want the value of "value", 0.5 Nano 0.5 Nano change.
Is there a way to do this in Lumerical(FDTD) ?
Thanks in advance for your reply.
Motahari
Relevant answer
Answer
Hello again
To solve the above problem,
First, enable the (''use linear wavelength spacing'') option as shown below, then pay attention to the rest of the description:
Determine the number of frequency points according to the type of divisions of your wavelength range. For example, if you want the distance to be 0.5 nano, then subtract the beginning of the interval from the end of it, then multiply by 2, and add 1 at the end.
Finally, the number of frequency points is determined.
For example, above is the number of frequency points:
(900-280)*2+1=1241
Thanks
Motahari
  • asked a question related to Optics and Photonics
Question
4 answers
comment
The analysis of the " Nanocomposites in optoelectronics and photonics " research topic is here
Notions, subtopics, basic knowledge and articles potentially with novelty
---
Анализ темы исследования (важнейшие статьи, термины, подтемы) - новый бесплатный сервис библиотеки УРФУ, предназначенный а) для ориентирования в новой теме; б) сбора материалов для раздела "состояние на сегодняшний день"; в) помощь рецензентам в объективной оценке научной работы.
Срок исполнения 1-4 дня.
Темы для анализа принимаются на почту v.m.kugler urfu.ru
или
прийти Мира 19, Главный учебный корпус, Б-105
Relevant answer
Answer
Please allow me to point you to my work at these three (3) files
I hope that you will enjoy the attached art, which was created during study of the above-referenced video.
With all best wishes, -Steve- gambist@gmail.com
  • asked a question related to Optics and Photonics
Question
6 answers
Dears,
I hope u r good.
I m looking for papers on optical/photonic waveguides for O band (1310 nm).
Can u plz help in citing a good literature?
Regards
Faisal
Relevant answer
Answer
Faisal Ahmed Memon, I have at the article for polymer waveguides @1310 and 1550 nm
  • asked a question related to Optics and Photonics
Question
3 answers
Optical chopper is a frequntly used device. It modulates CW signal to pulses. Mathmatically, when a CW signal is converted to pulses, it introduces new frequency sidebands. How is it possiable to generate new optical frequencies in a linear mechnical process? If it is true, what could be the physical mechanism?
Relevant answer
Answer
Yes, a chopper does change a CW electromagnetic radiation frequency. Well, more correctly, chopped radiation is not CW, and has different spectrum. First mode-locked lasers were made with a mechanically rotating mirror of the cavity.
To be able to measure the difference of the spectra for light, chopper should work at least at close to Mz range frequency, and CW light should be monochromatic to corresponding degree. There was a lab work for students demonstrating this effect when I was studing laser technology, but it used electrooptical shutter at tens of Mz.
  • asked a question related to Optics and Photonics
Question
7 answers
I am ICP etching AlGaAs Bragg structures using Ar, Cl2 and BCl3.
After etching (typically a few microns), there is material deposited on the surface and sidewalls of my photonic structures. I assume it is something like AlCl3... but I'm not sure.
I want to remove this deposited material as it increases the roughness.
I have tried H2O2, up to ~20% concentration, but this does not seem to help.
Does anyone know what the deposited material is, and how could I dissolve it away?
Relevant answer
Answer
Vapour pressure of Aluminium Chloride 133.3 Pa (99 °C) 13.3 kPa (151 °C)
  • asked a question related to Optics and Photonics
Question
5 answers
How can i check that the Circular polarized beam is Right-handed or Left-handed? I use a Quarter-wave plate to make the circular polarized beam. I don't mind any method.
Relevant answer
Answer
Maybe you can use Jones Matrix to do the algebra.
  • asked a question related to Optics and Photonics
Question
3 answers
What type of PCF is ideal for coherent SC generation for carrier envelope offset measurement of a modelocked laser. As far as I know, for coherent SC generation, PCF should be pumped in normal dispersion regime. Moreover, PCF should have ZD (zero dispersion wavelength) close to pump wavelength. Are there any other conditions to consider. Plz advice.
Relevant answer
Answer
follow
  • asked a question related to Optics and Photonics
Question
5 answers
UV-Vis spectrophotometer has a light detector that detects photons by current signals. But the detector itself cannot differentiate between a high energy photon (short wavelength) and a low energy photon (long wavelength). It can only measure the number. However, if we require the irradiance or power per unit area, we have to multiply the number of photons with the energy of the photons. Does the UV-Vis spectrophotometer show the power per unit area or number of photons?
My guess is that it shows the power per unit area because the Mie analytical spectra for plasmonic nanoparticles agree with UV Vis spectra.
  • asked a question related to Optics and Photonics
Question
5 answers
Hi,
I am trying to perform co-design and co-simulation of the electronic-photonic interface for optical splitter and an electro-optic data modulator. Please help me with the simulation methods that can be used for this purpose.
Relevant answer
Answer
I believe you'll be able to solve this problem using Comsol multiphysics which is a FEM based solver. Lumerical also offers a Design suite to specifically solve multiphysics photonic problems. You can find it here: https://www.lumerical.com/products/#device
  • asked a question related to Optics and Photonics
Question
7 answers
After recording the speckle contrast, next step is to measure it quantitatively and accurately. I am not sure how many pixels of an image should be considered for its calculation. Speckles were recorded under dark room condition.
It would be great if someone can tell from his/her experienece or recommend me a research paper about this specific issue. I searched but i was unable to find any papers or research work related to it.
Thanks in advance!
Relevant answer
Answer
Isn't that a question of satisfying the sampling condition? If you imagine the speckle pattern is formed from a range of plain waves (angular), then the highest frequency component is resulted from the interference between the two outermost, in angular term, plain wave components. This will set the limit of the sampling spacing you need to achieve, taking into account if you are dealing with intensity rather than amplitude.
  • asked a question related to Optics and Photonics
Question
6 answers
Hello dear researchers,
I want to measure the value of the third-order nonlinear susceptibility (Chi3). I have only the third harmonic generation (THG) spectra in photon counts and I know the input power at the sample to be probed. In literature, people used some materials whose Chi3 is already known and after comparison, they gave a rough estimation of chi 3. The other way in the literature was used is the utilization of an additional laser to calibrate the power.
I would like to ask is there any other way to measure the output power or chi 3 value? any simpler way if you know the input power and output intensity in photon counts???
Relevant answer
Answer
I have been using Degenerate Four-wave mixing technique to measure the third-order nonlinear susceptibility. In this technique, I isolate the signal and then measure the signal power with a sensitive photodiode sensor. I calculate back chi(3) using this measured signal power along with my input powers which has been divided into two pumps and a probe. Raul Rangel-Rojo Kaleem Ullah
  • asked a question related to Optics and Photonics
Question
2 answers
I want to overlap the Cs atom with a nanofiber. I am using two cameras but it is still not clear. So I added an external coil to AH coils to move them flexibly. Now the issue is how to minimize the external magnetic field!!!
Relevant answer
Answer
Yes, we have H coils in three directions. However, minimizing the external magnetic field is manipulated by any change in the frequency shifts of cooling beam and so on.
  • asked a question related to Optics and Photonics
Question
6 answers
We have LG10 beam only and we have to get HG(1,0).
Relevant answer
  • asked a question related to Optics and Photonics
Question
6 answers
Dear professors and colleagues,
I am going to to study effect of the two photons absorption in Safranin O. Safranin O is organic material, so I think that the power needed to activate this effect doesn't need to be too high. However, the two photons absorption is a third-order nonlinear optical effect, so it is usually implemented with high-power pulsed lasers. I cannot afford to buy high-power pulsed lasers. So, can I stimulate effect of two photons absorption in safranin O by continuous wave laser (808 nm or 1064 nm)? And how much is the required power of laser? I hope the colleagues who have experience in this experiment share me useful information.
I look forward to hearing from you. Thanks in advance.
Yours sincerely.
Relevant answer
Answer
Dear Nguyen, I beg You pardon, please read with attention my above given advice.. or at least tell us for what task You are going to apply TPA excitation then it would be possible to figure out correctly what laser beam intensity W/mm2 You was needed...
  • asked a question related to Optics and Photonics
Question
3 answers
Dear Colleagues,
I am investigating methods to determine the photodynamic activity of photosensitizers for photodynamic therapy. One of the methods being used is absorption spectrometry. A work concludes that significant absorption of light was shown to be prerequisite but not sufficient for high photodynamic activity. My point of view is: When a photosensitizer absorbs more radiation at a certain wavelength, it will produce more Ros (Reactive oxygen species), i.e the absorption maximum will correspond to the wavelength active photodynamic effect best. However, this point of view contradicts the viewpoint in above work. I look forward colleagues to explain this question.
Thanks in advance.
Relevant answer
Answer
Nguyen, It seems reasonable that the greater the absorption efficiency the greater the release of ROS. This applies to both exogenous photosensitizers and endogenous porphyrins. We are preparing a paper describing the absorption spectra of intact, live planktonic pathogens, both bacteria and fungi, collected with diffuse reflection spectroscopy. (Please see our papers: "The Black Bug Myth" and "Selective Photoantisepsis" posted on RG). I propose that these absorption spectra, if obtained in vivo, will mirror the action spectrum (clinical efficacy VS WL) of the clinical application.
  • asked a question related to Optics and Photonics
Question
4 answers
In the semiconductor laser, I have an equation (attached) that shows the relationship between optical gain and the number of carriers in a laser. In this equation I have a parameter by name of gain cross section.
I want to know the physical concept of that is.
Relevant answer
Answer
To pump semiconductor lasers optically instead of injecting a current is a common scheme. For example semiconductor disk lasers (VECSEL).
  • asked a question related to Optics and Photonics
Question
2 answers
Hi all,
I am attempting to implement 3D finite difference (FD) beam propagation method (BPM) based on alternate-direction implicit (ADI) method.
Does anybody know about how to implement or the formulation of transparent boundary condition (TBC) in 3D FD-BPM based on two step ADI method?
Any suggestions or advice would be appreciated,
Thank you!
Relevant answer
Answer
Dear Onur,
I am also trying to solve the waveguide propagation problem using x,y, and z co-ordinates using FDBPM. Could you please share your matlab code which might serve as a starting point for me.
Thanks in advance.
  • asked a question related to Optics and Photonics
Question
9 answers
I have three collimated optical beams with 1cm separation between the adjacent one. I want to shift one of the three beam laterally so that it goes closer towards or farther away from the adjacent beam by micrometer accuracy.
Relevant answer
Answer
Dear Sreeprasad
If you are not worried about relative phases and can tolerate a number of very weak secondary beams, perhaps the simplest way is to insert a tilted parallel glass plate into the beam you want to translate. The translation of the main transmitted beam will be Theta*T*(n-1)/n, where n is the refractive index of the glass plate, T is its thickness and Theta is the tilt of the plate's normal relative to the beam propagation direction (in radians). A 1 mm thick glass slide at 5 degrees will result in a shift on order of 50 microns. The main drawback from this method is that more than one beam is transmitted due to the multiple reflections at the glass surface, however the main transmitted beam will be several hundred times more intense than the strongest secondary beam.
Good luck
  • asked a question related to Optics and Photonics
Question
2 answers
One can argue for thin-film interference of protective oxide film (that has varying thickness) that have been eroded-corroded to various thickness. But why does this pattern last long? Does oxide film fail to form/grow to full thickness on the burnt region? even when the material is removed from heat source, the patterns still remain. And unlike thin-film interferance with varying thickness, The oxide film does not show any sort of VIBGYOR trend with temperature . Why does that happen?
Relevant answer
Answer
To form an oxide film, the metal has to react with oxygen. When an organic molecule on the metal surface is pyrolyzed, it consumes the available oxygen and prevents oxidation of metal. Only when the organic substance is fully decomposed (to carbon dioxide) and completely leave that surface, the metal will oxidize. Adsorption of carbon mono oxide on the metal surface will also prevent oxidation!
  • asked a question related to Optics and Photonics
Question
7 answers
I want to simulate a fiber modulator in Lumerical Mode solution by Eigensolver but the results depend on simulation region size. What is the simulation region size at metal boundary condition in Lumerical mode solution?
furthermore after eigenmode analysis in mode solution, I can't recognize TE and TM mode in mode list. Is the first TE mode and the second TM?
I would be very grateful if someone answer my two questions.
Relevant answer
Answer
Dear Akram,
If you want to choose the TE mode using script, what you were doing is alright. After select mode 1, you just check if the TE polarization is close to 100% or not. If not, select mode 2.
Starting from max index for Eigen Mode Solver to find the modes, the first two modes should be TE or TM mode.
  • asked a question related to Optics and Photonics
Question
9 answers
Hello Everyone,
I am doing my research in the generation of Optical frequency comb. I found a paper where they used nonlinear effect to enhance FWM by designing a fibers loop which connected with polarization beam splitter. I simulated that system in Optisystem but i didn't get the same results as in the paper. Then I designed the loop using connector with the splitter. But there is no impact of the loop in the system. Would you please help me that how can i make the fiber loop which will have an impact on the system??
I have attached both the reference paper and the .osd file.
Thanks in advance.
Relevant answer
Answer
Yes I solved the problem. You can check my publications, it has written there@ Surya Pratap
  • asked a question related to Optics and Photonics
Question
24 answers
It is said that light passing through a single slit forms a diffraction pattern. However, I couldn't find any research to say whether where this phenomenon starts? Before? Inside? Or after the single slit? At the inlet edges? Or at the outlet edges?
Please let me know if there is any reference for it.
Relevant answer
Answer
Finally, I finished making a device to check out where the diffraction starts. Here is a photo and I will explain the details.
Let's see how it is going on.
  • asked a question related to Optics and Photonics
Question
1 answer
Hello
I need to know the comparison between the 3 mentioned optical devices in terms of
1- Bandwidth in GHz
2- Silicon area to implement each
3- Sensitivity to heat, how much change in resonance frequency in Hz to 1C change in Temperature
4- Does any of them need specific technology, e.g. 22nm , 14nm, etc. to be implemented
Thanks
Relevant answer
Answer
For all these devices it is needed to know details about the device to predict the parameters that you are interested in.
For ring resonators they can be as small as having a 3um radius or large with 100um radius. The bandwidth is dependent on the Q-factor, which depending on fabrication quality and coupling region design can be anywhere between 1000-100 000. Similar trade-offs exist for all the other devices (e.g. the more waveguides you include in an AWG the better it will separate closely spaced wavelength, but it then also requires a larger trade-off.
  • asked a question related to Optics and Photonics
Question
7 answers
Well a yellow laser should be around 575-580 nm. Concurrently, mixture of green and red photons are also looks yellow. So can we call it as a laser or it will be just a high-powered yellow flash light?
Relevant answer
Answer
Mr. Kibrisli's question is, "is it possible to make a yellow laser ...". If we interpret the question as asking to make a laser that emits the spectral color yellow accompanied by a spectrum with a single spike at about 575nm, then using a red laser with wavelength at about 670nm and a green laser with wavelength at about 540nm would not work. The two lasers would show a spectrum with two peaks and would not possess the coherence of a true yellow laser. However, the human vision system would interpret the color as yellow in much the same way it interprets light combined from a red and green LED as yellow. So YES to your 'high powered yellow flashlight' characterization. Another view: your red + green = yellow laser would not excite a linear medium with a yellow resonance. Maybe that is a good test criterion for producing a yellow laser.
  • asked a question related to Optics and Photonics
Question
11 answers
I have started working on Inverse Design for passive photonics Devices. For that I need a reference matlab code .
Thanks for your help.
Relevant answer
Answer
Have a look at the followings. You will get some clue.
b)
https://www.ncbi.nlm.nih.gov › pmc › articles › PMC6361971
c) https://www.spiedigitallibrary.org › 12.2236685.full
  • asked a question related to Optics and Photonics
Question
6 answers
My question is:
With its own white-light source, is there a practical method to obtain parallel light coming out from objectives of a commercial microscope?
Thank you for paying attentions to my question.
Jiancai
Relevant answer
Answer
If you use point source of monochromatic light source put in the the focus of a collimating lens you obtain a parallel beam. The point source may be a LED with very small area.
Best wishes
  • asked a question related to Optics and Photonics
Question
10 answers
i am planning to simulate photonic qubit and quantum dot based quantum computing.
Relevant answer
Answer
Hello
In this time i try to make some circuits having best performance ..so i work in the theorical hand but in the experimental one i can not to be useful
have good day
  • asked a question related to Optics and Photonics
Question
3 answers
Teeside University, CPI and Durham University are looking for a PhD studentship candidate to work in the area of healthcare photonics:
"Development of novel optical measurement tools for measurement of Vital Signs necessary to generate Standardised Clinical Early Warning Scores. ":
The position is a mix of academic, working with an industrial partner and working with CPI (part of the High Value Manufacturing Catapult). .
Relevant answer
Answer
I am told that the closing date for this post has been extended. The instructions on how to apply are contained within the link originally posted.
  • asked a question related to Optics and Photonics
Question
3 answers
I am trying to get output of laser beam from a FOC laser beam with diameter ranging from 100 microns to 1000 microns. The FOC diameter is 200 micron and NA is 0.22. What kind of lens or combination of lenses is possible to do this kind of focussing and how much should be the focal size of the lens. Any additional info is also welcome. Thanks
Relevant answer
Answer
As John explained, it is not possible from a 200µm/25° light source to get a collimated beam from 100µm to 1000µm. The beam parameter product of your source (diameter×divergence) is a constant. You can then expect 100µm/50° or 1000µm/5° spots. Now if you want spots ranging continuously from 100µm to 1000µm, I would look first for a 10× zoom lens (5-50mm for instance). I would then collimate the output of my fiber with a FOC with twice the shortest focal length of my objective (here 10mm). The collimated beam passing through the zoom will give you at the image plane spot sizes ranging from 100µm to 1000µm . However, the equivalent aperture of your source is F/2.2. It means that the aperture of your zoom have to be greater than F/1.1 for your 100µm spot if you do not want to lost energy and it will be hard for 10× zoom lens. If you can deal with a 30% loss at 100µm, it should work. Good luck.
  • asked a question related to Optics and Photonics
Question
4 answers
I am trying to build a fiber laser based on multimode interference in SMF-GIMF-SMF (GIMF spliced between two SMFs) leading to saturable absorber phenomena in the design. I am using Er fiber as a gain median and pumping it by 980nm source. I observe Q-switching or sometimes unstable or weak mode-locking. What can I improve or add in this setup to achieve better modelocking.
Relevant answer
Answer
Aktham Tashtush Its a ring laser. Thanks for suggestion , I'll definitely consider it.
  • asked a question related to Optics and Photonics
Question
4 answers
Fano resonance is a distinctive spectroscopic behavior in many optical systems. There're certain differences in terms of physics and behavior of Fano resonance compare to dipole resonance which is well recognized. But, what're the specific benefits of Fano resonances over dipole resonances in application point of view or device aspects?
Relevant answer
Answer
A typical Fano resonance is obtained when a totally reflecting prism is coupled to a planar waveguide. When the guided wave is not lossy, with an incident gaussian beam, the reflected Fresnel field exhibits a dark line followed by an interference pattern. The light is coupled in the waveguide and after a small path decoupled in the reflected field. Interferences occur between this decoupled field (resonance) and the field directly reflected on the prism base (continuum). The prism coupler is very sensitive to the optical properties of the planar waveguide and can then be used as a sensor.
  • asked a question related to Optics and Photonics
Question
1 answer
1) I would like to ask you about a criteria from your experience to help me decide on the values constituting the background noise that I should suppress from my signals while doing data analysis of data acquired via spectrometer (Intensity counts and wavelength). If I have 4/5 spectra I want to make them start from zero.
2) Is there a formula (set of formulas) that take (s) into account the dependency of the spectrum (wavelength drift) with respect to frequency, voltage and temperature ?
Thank you very kindly and in advance for your contributions.
  • asked a question related to Optics and Photonics
Question
14 answers
I need to collimate light beam of an LED (white light)  using a plano convex lens of focal length : 75 mm. If I place my LED at the focal plane (focal point) of the lens, will the lens collimate the beam of light from the LED or not? If the plano-convex lens does not collimate the beam fully, then what type of collimation will it be called as?
Relevant answer
Answer
What LED source are you using? I was able to focus most of the light using a half-ball lens from EdmundOptics
It gave me almost collimated beam, which I then tight focused using a 5x objective (EFL 40mm).
You can also play with this online simulator, and see that a point source+half ball combination can give you a nice collimated beam https://ricktu288.github.io/ray-optics/simulator/
  • asked a question related to Optics and Photonics