Optical Engineering

Optical Engineering

  • Oussama Bouzid added an answer:
    2
    I would like to know what are the best techniques to generate laguerre gaussian and hermite gaussian high order laser modes?
    Oussama Bouzid

    Thank you Mr.Pawluczyk for this detailed answer.

  • Shigeo Kubota added an answer:
    11
    How does collimated beam suffers from beam waist and how cylindrical lens helps to eliminate beam waist?

    A collimated beam suffers from beam waist. When such a beam falls on grating the dispersion does not appear good. But this problem can be solved by the use of cylindrical lens how?

    Shigeo Kubota

    Sibasish,   Basic idea behind my answer is that the spectral linewidth of grating is analogous to the linewidth of the multiple beam interference pattern after multiple slits, which becomes sharper and sharper when the number of relevant slits is increased.    Shigeo

  • Palash Gangopadhyay added an answer:
    6
    How to create "flat" liquid-liquid (e.g. water - dodecane) interface?
    I am trying to create "flat" liquid liquid interface for optical ellipsometry measurements. Refractive indices of the liquids will dictate a total internal reflection type system that should let me get a good quality laser beam out after reflection. A mirror flat interface is paramount, since I need to send back the beam for a second reflection for non-reciprocity measurements. The two liquids are obviously not miscible and need to have different refractive indices. My test case of water - dodecane always ended up curved, resulting in poor reflected beam quality. My efforts so far have been confined to making the water side of the glass cuvette hydrophilic and the dodecane side hydrophobic. Any ideas or suggestions are appreciated. Thanks!
    Palash Gangopadhyay

    Dear Christian,  

    Thanks for your input.  We solved this issue as well.  We make hydrophilic -hydrophobic coating on the glass cell wall on the water and dodecane sides respectively.  A sharp interface on that, can be achieved simply by i) first coating the inside with a photoresist and expose it from outside, lets say the top half, ii) then clean the bottom half of unexposed resist and coat it with a hydrophobic silane, iii) now clean the top part and repeat the process with a hydrophobic silane.  We get best results with this.  However, another easier way to do this, is to have a smaller (say covering half the height) teflon cell constructed that will fit inside the larger glass cell, by placing it upside down.  The smaller teflon cell should have a circular hole on top cover.  Now build the water layer inside the teflon cell until it reaches the hole height and then gently build the dodecane layer on top.  The flatness of the interface obviously depend on the size of the hole and smoothness of the wall surrounding the hole in the teflon cell. 

    Thanks,

    Palash

  • Hans Kettling added an answer:
    3
    Has anybody used high-performance plastics (e.g. PEEK) for housing of optical components - any recommendations?

    I am trying to build a lightweight optical layout containing some freespace optics for field testing. It consists of a few mirrors and a camera, but would like the housing to be lightweight and use some kind of plastic.

    I am wondering if anybody has any previous experience with building custom plastic housings for optics, but robust enough to hold a few mirrors stably (to a precision of say, 1 mm).

    I've recently heard there are some incredible plastics such as PEEK from Victrex  but wondering if there were more commonly used places.

    Hans Kettling

    PEEK works fine for us as well. Teflon has the disadvantage that it is a bit harder to machine (too soft). PEEK should not be used as a beam dump for high power lasers.

  • Sushank Chaudhary added an answer:
    4
    Which software can be used for simulation of raman spectroscopy other than optisystem?

    I tried with optisystem, but sample is an issue. I can't find any component which is a good substitute for a sample. Please provide me with a solution!

    Sushank Chaudhary

    OptiFDTD and OptiBPM can be used for raman spectroscopy simulation.

  • Akhilesh Gothwal asked a question:
    Open
    Hello, while planning on link budget tool (Pathloss) I am not getting any multipath but during implementation I am not getting RSL as per design?

    Hello, while planning on link budget tool (Pathloss) I am not getting any multipath but during implementation I am not getting RSL as per design?

  • Michał Dudek added an answer:
    1
    How is it possible to define a 3rd order nonlinearity (chi3) tensor in Lumerical?( I mean a full tensor not a diagonal one)?

    Lumerical can define diagonal chi3 tensor only.

    it is possible to define a full matrix for permitivity, but what about chi3 tensor?

    Michał Dudek

    I think it would be better for you to ask this question directly in the Lumerical Knowledge Exchange.

  • Milad Taleb Hesami Azar added an answer:
    3
    How can I find the propagation constant of different modes in a multimode fiber?

    How to numerically find the values of propagation constant of different modes inside a step index multimode fiber using eigen value equation??

    Milad Taleb Hesami Azar

    You can find answer at related book in your research area such as fiber optics engineering. 

  • Nishit Malviya added an answer:
    22
    Which software is most suitable for Photonic Crystal Fiber analysis?
    Dispersion vs wavelength, MD vs lambda.
  • Denis G. Baranov added an answer:
    6
    In PT-symmetric dual waveguide systems, what is the meaning of reciprocal and nonreciprocal wave propagation?

       In PT-symmetric dual waveguide systems, what is the meaning of reciprocal and nonreciprocal wave propagation? has it some relationship to unidirectional invisibility?

    Denis G. Baranov

    PT systems CAN NOT violate reciprocity period

  • Oscar A. Van der Velde added an answer:
    3
    Can anyone tell me about the following error using scilab

    Hello Everyone

    I want to track an image using scilab. When I interface my USB cam with scilab I got the following error;

    n=camopen();


    !--error 999
    camopen, Can not open the camera.

    Oscar A. Van der Velde

    I once experimented with this SIVP module and this simple command worked fine for my webcam. The problem could be in the image format not being supported? Have you tried different cameras or USB capture devices?

  • Dorit Munzke added an answer:
    5
    How do I connect an NIR LED to an SMA-terminated optical fibre?

    I'm interested in directing as much light as possible from the LED into the SMA-terminated optical fibre. What sort of adaptor or bushing would I need to be able to connect the LED to the fibre? I am using Osram SFH 4725S for the NIR LED and a lab-grade patch cord from Ocean Optics.

    + 1 more attachment

    Dorit Munzke

    I am applying free-space laser diodes. For coupling light into an optical fiber (SMF in my case), I am using optical lenses and either a fiber port or a fiber collimator. Thorlabs offers reflective collimators: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=4093 So collimating the laser beam and using such a reflective collimator might work in your case. But I do not have any experiences with LEDs.

  • Ahmed Fawzy Daw added an answer:
    4
    What is the meaning of negative permittivity?

    Metals have their negative permittivity at optical frequencies. 

    Ahmed Fawzy Daw

    i think , this ref have very good answer for your question:

    ELECTROMAGNETIC METAMATERIALS: TRANSMISSION LINE THEORY AND MICROWAVE APPLICATIONS
    The Engineering Approach
    CHRISTOPHE CALOZ

    University of California at Los Angeles

  • Sivacoumar Rajalingam added an answer:
    2
    Is any researcher interested in 5-fold symmetric photonic quasi crystals?

    I am working on 5 fold symmetric photonic quasi crystal fiber properties. Are there any interested researchers up for discussion and collaboration? Regards and Thanks. 

    Sivacoumar Rajalingam

    Thank u Kraus.. I will contact .

  • Xiaoguang Zhang added an answer:
    3
    Is there a publication where the Shannon capacity formula is derived for SDM systems?

    is there a publication where the Shannon capacity formula is derived for SDM systems (few modes fibers and/or multicore fiber)including the impact of nonlinear effect and mode dispersion loss?

    Xiaoguang Zhang

    No fiber channel

  • Pravin Vaity added an answer:
    3
    Is is possible to make multiple optical trap for dielectric particles with stationary interference pattern formed from back reflection of mirror ?

    Here, I suppose to use an objective lens and a Hot mirror. My supervisor claimed that the stationary interference formed between objective and mirror can create optical traps. The intensity maxima can trap dielectric particle. As far as I know optical trap can form through tight focusing only. If you know any related article please let me know? 

    Pravin Vaity

    Thanks for help. But in mentioned studies, particle was trapped in single plane. My Prof. is interested in trapping particle in multiple planes. According to me, diverging nature of gaussian beam wont allow to trap multiple particle in stationary interference pattern along the beam propagation direction.

  • Grzegorz Dudzik added an answer:
    7
    Can cylindrical nozzles produce microscopic supersonic gas jets?

    Regarding gas jets for laser interactions, such as generation of high harmonics - I've seen articles that discuss nozzle designs for producing supersonic gas jets. Those articles always discuss a converging-diverging nozzle design for supersonic jets. I wanted to ask if it's possible to produce a supersonic gas jet also with a simple cylindrical nozzle? I'll appreciate if you can also refer me to a specific scientific source discussing this point. 

    Grzegorz Dudzik

    Hi,

    In ordinary cylindrical nozzle it is not possible. But you can use the de Laval nozzle where supersonic gas jets are achieved (i.e. in plasma or cold spray process).

  • Elizabeth Frances Cloos Dreyer added an answer:
    10
    How many optical cycles does it take for Rayleigh scattering to occur?

    I am trying to detect Rayleigh scattering from a liquid and am concerned that my optical pulses are too short. I am using a 13 fs, 80 MHz Ti:Sapphire laser. So, there are about 3 optical cycles per pulse.

    In an old experiment where we had pulses of 150 fs, 1KHz, we did not have any trouble finding it. 

    How many optical cycles does it take for Rayleigh Scattering to occur?

    Elizabeth Frances Cloos Dreyer

    Hi everyone,

    Thank you for your previous input. It now seems that my question was misguided and it is a problem with the sensitivity of my entire detection scheme.

    Thank you for your help.

  • Sridhar Iyer added an answer:
    6
    In an OFDM-optical network, how will spectrum overlapping between connections (served at their requested transmission rate) affect the RMLSA problem?

    In an OFDM-based optical network, how will spectrum overlapping between connections (which are served at their requested transmission rate) affect the Routing, Modulation Level, and Spectrum Allocation (RMLSA) problem?

    Sridhar Iyer

    Thanks a lot Kalpana.

  • Axat Patel added an answer:
    4
    Can anybody share a document regarding Zernike analysis in optomechanical systems?

    Can one share me document regarding zernike coefficients and its application in optical engineering....

    Axat Patel

     Thanks neeraj

  • Jaime Viegas added an answer:
    2
    Can anyone recommend some water soluble UV curable photopolymers?

    Liquid photopolymer with low viscosity, and curable at 405 nm or other UV range with low fluence. Most importantly, un-cured photopolymer can be simply wash away by water afterwards during a development step.

    Jaime Viegas

    Hi Peijun He,

    I would look for polyvinyl alcohol formulations.

    Look for example at these two papers:

    "UV-cured poly(vinyl alcohol) ultrafiltration nanofibrous membrane based on electrospun nanofiber scaffolds", Zhaohui Tang, Jie Wei1, Lewis Yung, Bowei Ji, Hongyang Ma, Changquan Qiu, Kyunghwan Yoon, Fen Wan, Dufei Fang, Benjamin S. Hsiao, , Benjamin Chu, on Journal of Membrane Science, Volume 328, Issues 1–2, 20 February 2009, Pages 1–5. doi:10.1016/j.memsci.2008.11.054

    or

    "Preparation and characterization of UV-cured hybrid polyvinyl alcohol nanofiber membranes by electrospinning"

    Bihter Zeytuncu; Süleyman Akman; Onuralp Yuce; MemetVezir Kahraman, Mat. Res. vol.17 no.3 São Carlos May/June 2014 Epub May 09, 2014

    Or you can get commercial grade material here:

    http://www.polysciences.com/default/polyvinyl-alcohol-n-methyl-44-formylstyrylpyridinium-methosulfate-acetal

    Irgacure (commercial brand) may also be a good source of water soluble UV curable photopolymers.

    I hope this helps you.

    Regards,

    Jaime

    Disclaimer: I am not affiliated with any of the above brands.

  • Soso Alsheheri added an answer:
    2
    Why do we have a blue shift when we increase the degree of truncation for Ag nanoprism?

    by simulation, we notice that if we truncate the corner of Ag nanoprisms we have a blue shift and also by increasing the degree of truncation causes increasing in the blue shift in the resonant wavelength of Ag triangular prism structure. please if any one can give any article that explain why do we have blue shift??? Thank you  

    Soso Alsheheri

    Thank you so much

  • Artur Braun added an answer:
    1
    What is the complex refractive index of FTO TEC15?

    I need to model the optical properties of electrodes deposited on TEC15 substrate. Does anybody knows their complex refractive index  in the visible spectrum?

    Artur Braun

    http://www.rsc.org/suppdata/ee/c4/c4ee03224a/c4ee03224a2.pdf

  • Felipe Beltran-Mejia added an answer:
    3
    How can I calculate cladding line (cladding effective index) for a photonic bandgap fiber?

    I need to calculate the cladding line (referred as cladding effective index) for a photonic bandgap fiber. How may it be done?

    Felipe Beltran-Mejia

    Sorry if I didn't explain myself well enough. I'm not saying you have to model the air-hole structure along with the rest of the cladding. What I mean is to model just the microstructured region as this must give you an approximate result. This approach, as well as yours, is only approximate. The exact solution will be as Birks et al said in their paper,

    "The FSM is the fundamental mode of the infinite photonic crystal cladding if the core is absent, so 𝛽FSM is the maximum 𝛽 allowed in the cladding"

    that is, to calculate exactly the space-filling mode (FSM) you have to use periodic or infinite conditions.

  • S. Selvendran added an answer:
    6
    Is there any relationship between data rate and mach zehnder modulator losses?

    I am working on Passive Optical Network. I have designed the two transmitter one with data rate of 10 gbps and other with 1gbps. I have used mach zehnder modulator. I have set the laser power of both transmitters to 0 dbm. It is found that the losses are less in case of 10 gbps as compared to 1gps. Is there any relationship between data rate and mach zehnder modulator losses?

    S. Selvendran

    optisystem  simulation tool is exactly suitable for you requirement... you can download this tool for 30day evaluation (full latest version) from the optiwave website....  

  • Alan Robinson added an answer:
    3
    Please suggest suitable laser diode to convert up to 20 volt input signal into optical signal?

    Dear all

    I have to make a transmitter  which will convert electrical signal to optical signal and transmit over fiber up to 5 meter distance the range of input signal will be 10 mvolt to 20 Volt. pls suggest suitable laser diode for this range.

    Alan Robinson

    The voltage response of diode lasers is highly non-linear.  Converting the input voltage to current, as suggested by David, will greatly improve linearity (and reduce the likelihood of destroying the laser).  However, although the optical intensity increases more linearly with current than voltage, laser diodes typically exhibit a lasing threshold current below which the output is very weak.  This can be offset in the driver, but the threshold is sensitive to laser junction temperature, so with a constant current drive the output will drift with time as the ambient and laser temperatures change.

    David's advice to use a voltage to frequency converter is sound.

    If an output with reproducible optical intensity is essential, then some kind of feedback control is highly desirable.  Many lasers are provided with a monitor photodiode which delivers a current proportional to the optical output from the laser cavity.  Alternatively, a fibre tap coupler and a separate photodiode offers the same functionality.  Many commercial laser driver modules support these configurations.

    What type of fibre are you using?  What is the core size, numerical aperture and operating wavelength?  Is it single mode or multi-mode?  A collimated laser output may not be the best option.  Additional optical components could be needed to couple power efficiently into the fibre core if the core is not comparable in diameter or larger than the laser beam width.  Depending on the type of fibre, laser diodes should be available with matching or compatible pigtail fibres, and this may be a simpler option, especially if you can use a splice or fibre connector.

    + 1 more attachment

  • Kate Peters added an answer:
    3
    How can i make a microelectrode wiht closure in glass?

    when i used a lot of gluse to enclose the glass in order to get plane microelectrode. how can i get help from the experiments

    Kate Peters

    If you want to fabricate carbon fibre electrodes you can use glass tubing and an electrode puller to get a tight seal no need for glue, or you can use Clark et al's (attached) method of encasing the carbon fibre in glass capillary with epoxy glue. But it depends on what materials you are using for the sensor. The Clark type electrodes are suitable for both in vitro and in vivo use in cyclic voltammetry and other applications.  

  • Stefano Penna added an answer:
    4
    What has the highest priority in the design of a slot waveguide EO modulator between the effective area and the optical confinement factor ?

    I'm having a long discussion with my boss concerning with the optimal design of a slot waveguide EO modulator. He considers that the maxmization of the optical confinement factor into the slot has the highest priority with respect to the minimization of the optical mode effective area, as the final aim is to maximise the overlap with the RF field into the slot, whereas the minimum effective area impacts mainly in devices based on light-to-light interactions, such as in all-optical modulators. Nevertheless, almost all the publications on this topic reports on efforts to minimize the effective area. What's your opinion about it ?

    Stefano Penna

    I had a deeper reading and some calculations starting from your replies. As Patrick said, the aim with Kerr effect materials is to minimize the mode effective area Aeff,  as the non linear interaction factor is maximized by minimized Aeff. This is true as Kerr materials are never used for standard EO modulators but only for all-optical non linearities, as frequency combs or FWM. Checking better the publications from the Karlsruhe KIT  group, they use standard Pockels effect polymers for modulators and Kerr effect small molecules for all-optical interaction based devices.
    Indeed, if we used a Kerr effect material into EO modulators and we derived the half wave voltage, we'd have a linear dependence on the inverse of the confinement factor (as we need anyway to overlap the driving RF electric field to the optical field) and only a square root dependence on the effective area (square root as Kerr is a quadratic effect). So this would mean that the half wave voltage would be improved more by the maximization of the optical confinement  rather than by the minimization of the effective area.

  • Mostafa El-Aasser added an answer:
    3
    Can anybody explain the d{ln(αhν)}/d(hν) versus hν plot ? And also, how can I calculate it if I have data between absorbance and wavelength?

    For optical studies the terms many a times I have come across this term please help ?

    Mostafa El-Aasser

    I think Stewart covered everything and mentioned all details.

  • Alexander B. Missyul’ added an answer:
    1
    How can I study the optical property of Mn-doped TiO2 if Mn2O3 impurities are present?

    I have made some black powder sample, which is confirmed by PXRD to be a mixture of rutile TiO2 and a-Mn2O3 . There is possibly also some Mn-doped TiO2 inside, as the XRD peaks for TiO2 shift a bit. 

    Now I would like to know the optical properties of the Mn-doped TiO2, but it seems to be completely masked by the black a-Mn2O3 impurties.

    So is there any method that I can isolate and study Mn-doped TiO2 alone? Is it possible that I can dissolve the mixture in some solution with properly tuned pH which can specifically remove Mn2O3 and leave TiO2 intact?

    Thanks a lot.  

    Alexander B. Missyul’

    I would try to dissolve Mn2O3 carefully in the acidic solution of the Mohr's salt (the procedure similar to what is used for the determination of the mean oxidation state of the transition metals by titration). But it will probably require very accurate tuning of the experimental conditions in order to avoid reduction of the Mn+4 in TiO2.

    Anyway, it is unlikely that you will be able to dissolve Mn2O3 simply by tuning of pH. Mn3+ easily disproportionates to Mn2+ and MnO2 in the water solutions and selective removal of the solid MnO2 will be much more complicated.

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Optical engineering is the field of study that focuses on applications of optics.

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