Optical Fibers - Science topic

Why are other elements such as calcium, oxygen, sodium, magnesium, aluminum, silicon and molybdenum visible in the EDX spectrum of tapered optical fiber (SMF‐28) covered with palladium and copper by sputtering method? Do all these foreign elements like silicon belong to the optical fiber itself?

I understand that ED-XRF or WD-XRF only allows for high energy photon emission. I am wondering if it is possible to obtain emission in the visible region by attaching an external optical fiber to a spectrophotometer (Ocean Optics)? However, I am skeptical about this since the chambers used for XRF are typically sealed. Do you have any other suggestions?

Dear community members,

I need to study the fluorescence of certain analytes in an aqueous solution. Currently, I am investigating fluorescence in a physiological solution. To conduct this study, I am using an Avantes spectrophotometer.

My goal is to obtain calibration curves for specific analytes in water at different concentrations.

The experimental setup consists of a peristaltic pump drawing the aqueous solution from a beaker containing the analyte. The solution flows through a plastic tubing. A small section of the plastic tubing consists of a circular plastic cuvette housed inside a light-shielded box. Inside this box, there are two LEDs and the entrance of the optical fiber that captures the light from the LEDs and the fluorescence of the solution excited by the LED light. Once crossed the box containing the LEDs, the liquid through the plastic tube returns to the beaker where the solution is recirculated for the experiment.

As mentioned, there is an optical fiber that captures the light from the LEDs and the fluorescence of the analytes dissolved in the water. The captured light travels through the fiber and goes into the box where the conversion of the light signal to an electrical signal takes place, along with all subsequent electronic processing. The spectrophotometer is connected via Ethernet to a Raspberry Pi, and I see the software interface on the screen to manage the spectrophotometer parameters. We have two LEDs: LED 1 emits light at 445 nm, and LED 2 emits light at 340 nm. One analyte absorbs at 445 nm and emits fluorescence between 500 and 600 nm, with a peak at 523 nm. Another analyte absorbs at 340 nm and emits fluorescence between 400 nm and 600 nm with a peak at 461 nm.

Now that I have explained the operation, let me describe the optical problem I am encountering.

In short, I observe a problem of "drift" in the light intensity detected by the light-to-electric signal converter. Let me explain it better. The LEDs (unless proven otherwise) always absorb the same amount of current (the voltage across the resistor is always the same over time, and they operate in the linear region), so they always emit the same light intensity. I observe that depending on how I bend the optical fiber and how it is touched and moved, the optical fiber affects the detected light signal, accentuating or attenuating a constant increase in detected light. If the optical fiber remains bent with very pronounced curves, I observe the drift phenomenon, i.e., a weak but constant linear increase over time in the light intensity of the LEDs or the fluorescence of the analytes, as shown in the plot attached. Let me explain it better. If the fluorescence peak of an analyte at 523 nm is, for example, 250 counts at a certain concentration, if no additional concentration of the analyte is added, and the circulating solution is always the same, then the fluorescence of the analyte at that constant concentration should remain constant. Instead, I observe a linear, weak but persistent increase in the fluorescence of the analytes at all emission wavelengths. So, if at time t, I observe fluorescence at 523 nm equal to 250 counts, after, for example, t + Dt, now the entire spectrum has grown, and, for example, the peak is at 1000 counts. Obviously, this "drift" in light intensity is not due to the LEDs because I believe their light intensity remains constant over time since the current they receive remains the same. At most, the LED intensity should decrease over time. It is not due to the auto-fluorescence of the analyte from ambient light because this phenomenon is observed even when the room is completely dark. There are no chemical reactions or degradation of the analytes (I would observe a decrease in fluorescence, not an increase because the degradation products of these substances do not absorb at 445 or 340 nm). Also, this positive drift phenomenon is observed even with plain water or air. It is not due to problems with the light-to-electric signal conversion electronics or due to bugs present in the source code.

I attribute it to the optical fiber, which, if it is straight, this problem is attenuated, but if it is very bent, this effect of increasing the detected light manifests. Attached, you will also find photo and plot files showing the abnormal trend over time of the fluorescence of the analytes or the light captured by the LEDs. I do not believe this anomalous trend depends on the light source.

I'm using a FT600EMT - 0.39 NA, Ø600 µm Core Multimode Optical Fiber

In your opinion, what could this uncommon phenomenon in the optical fiber be due to? And how could it be resolved?

I would appreciate any suggestions. Thank you for your patience and the time you've taken to read my question.

Best regards,

Lorenzo

optical fiber

optical fiber

losses

refractive index for core and cladding

normal refraction or total internal refraction

photonic crystal fiber

Hi all, I am using a CFBG with the following parameters:

Center wavelength = 1035nm

D = 0.372 ps/nm

3dB reflection bandwidth = 18nm

For SMFs, D is given in the units of ps/nm.km, GDD is simply: GDD = GVD x fibre length, where GVD is D*lamda^2/2*pi*c.

However, CFBG's D value is given in ps/nm, and the vendor does not mention the length of CFBG. I am wondering how I can convert CFBG's D value given in ps/nm into GDD in the units of ps^2 to calculate the net laser cavity dispersion.

Thanks in Advance!

I require assistance regarding this issue:

How does a change in length of an optical tapered fiber impact the interference between different modes? If an optical fiber sensor relies on mode interference, how does the sensor's performance change with variations in the tapered fiber's length? Are there any relevant formulas to address this concern?

keywords: taper, optical fiber, propagating modes, optical fiber sensors

When we receive the output of the sensor through the photodiode on the oscilloscope, it is in volts per pascal (sound pressure applied to the sensor), but to remove noises, etc., we need to convert this characteristic of the sensor into phase sensitivity.

How to convert mV/Pa to rad/Pa in the sensitivity of optical fiber sensors?

I manage to saw in both articles where they mention the materials' nonlinear response towards light are difficult to control with simple fabrication process. Unless we are using MBE technique.

Is there any reference article which discuss this in depth and it will be great if you can recommend articles that provide a SA fabrication method which is repeatable.

I tried fabricate quite a number of SA (especially graphene and MoS2) but its not repeatable as mentioned in the artcles. Its more like I have to trial and error until 1 SA can suddenly being used in my laser setup.

Thanks in advance.

How do I convert ytterbium ion absorption of 280 dB/m at 920nm into db/m at 977nm?

By converting AC to DC then to light signals,then is it possible to transmit the light signals through optic fibre cables?  

I attempted to measure the intensity of the light. But I also planned to measure refractive index. We used a laser transmitter and receiver. I use Autonics FD62010, stripped it half (only on 1 side) with a cutter manually and then do electrospinning on the stripped area. We attempt to create concentration gas sensor.

We working on translucent concrete. Could anyone help us giving the vendor/supplier details for using in translucent concrete? Thanks in advance.

Hello,

I wanted to know if a lensed fiber can guide a light of wavelength (1550 nm) longer than the working wavelength of the fiber (780 nm).

Thanks.

I want to optimize the different parameters to limit the dispersion in the optical fiber, which objective function to use according to these parameters, and the initial dispersion in order to estimate the error, thank you in advance

Almost all optical fiber manufacturers produce optical fiber bobbins length of maximum 50 to 100kms. If longer length bobbins are produced then it will be easy for both user and producer as it reduces cost.

suggest If any technical papers available on this

Hello

I asked about nonlinear phase shift φNL in optical fiber. How can estimation φNL? and how the power effected on it?

I am trying to modify optical fiber with gold nanoparticles for particle plasmon resonance applications.

I am using 2% 3-Mercaptopropyl)dimethoxysilane (MPDMS)/Toluene as silanization.

I tried different time of fiber immersion in MPDMS (2 to 20h) and gold nanoparticle solution(2-16h). But no gold particles(AuNPs) stick to the optical fiber.

Can anyone give me some suggestions how to do this?

You can also suggest some other easy ways to modify fiber with AuNPs.

I am currently working on optical fiber. It would be great if I get some suggestion on books or tutorials to study in details of optical fiber starting from the basic theories.

How can we draw a graph of transmission in terms of wavelength in optical fiber sensors? Is there a mathematical formula in this field?

I want to proceed the experiment using optical fiber. However, there is a problem. In one of the processes, the temperature reaches almost 600 degrees(Celsius). I know that the glass transition temperature of the soda lime glass is around 600 degrees.

In addition, the commercial glass optical fiber is consisting of 3 parts, core(pure silica) cladding(doped silica),and buffer layer(polyimide). The company says that this fiber can endure even at 400 degrees because of the polyimide, which is heat-resisting polymer. But, I think that it can endure up to 600 degrees if there is no polymer. Is it true? I will use the fiber as just a substrate, so I don't need any other layer except the core.

After I etch the polymer, what is the limit temperature for the glass optical fiber? 

Using COMSOL I want to observe the self-image phenomena in singlemode-multimode-singlemode (SMS) fiber. But there is some problem that could be due to boundary condition. How to use boundary condition for this case?

We are trying to visualize stress rods in polarization maintaining (PM) optical fiber and so far we have used UV light source (310 nm) to visualize stress rods in PM fiber. The resulting image is not having much appreciable contrast difference. Is there any other way of doing this ?

I've made good optogenetic fiber implants for lasers in the past using lower numerical aperture (NA) silica core fiber from Thorlabs.  Recently, we've been working with LEDs which require a higher NA fiber in the 0.6 - 0.7 range. The highest NA fiber that Thorlabs carries is 0.5. Prizmatics has the right silica core fiber with high NA, but they only have core diameters of 200um & 250um.

Does anyone know a good vendor for this kind of fiber ( bare fiber, silica core, ~0.65NA)?

Hello everyone,

I am looking for an optical fiber where the cladding is removed at one end (about 1cm long). I have read some papers that explain how to do it, usually with HF, but I would like to know if there are providers that offer this type of product. So far, I know Thorlabs doesn't offer it.

Thanks in advance!

Hello,

We are exploring the fabrication of an optical coupler ( fused biconic taper type ), where 1 fiber is having 80 microns cladding diameter with a LP11 cutoff around 850 nm. The other fiber is a standard 125 microns cladding diameter SMF ( LP11 cutoff around 1250 nm). It is understood that the first fiber will be lossy at 1550 nm. My question is if we want to taper both of these fibers to say 10:1, what would be the problem with 1 of them having a much lower cutoff wavelength ?

Hello, i hope you are doing well, i want to know how the etching of the cladding of an optical fiber is done in a controlled way, does anyone have a method or know somewhere i can do that ?

Dr E. M. Wright

I am using Quick View mode of the Ocean View software for Ocean FX spectrometer.

When I check the Dark Spectrum (taken when the fiber inlet is closed and the Spectrometer is covered with Black cloth and the Background Spectrum is when the Optical fiber is placed when no source is there, only ambient light is ON.

I would also like to know why there is a dip around 550 nm?

I would like to calculate the Mode Field Diameter of a step index fiber at different taper ratios. I understand that at a particular wavelength, the MFD will be decreasing as the fiber is tapered. It may increase if it's tapered more. I am looking to reproduce the figures ( attached ) given in US Patent 9946014. Is there any formula I may use ? Or it involves some complex calculations?

Most of the authors presented their work on Mach-Zehnder modulator in fiber optic communication. When I saw Mach-Zehnder Modulator on internet for buying it is showing it with fiber optic cable both sides of Mach-Zehnder Modulator(input and oupt side). My question is that can we use Mach-zehnder modulator for intensity modulation in wireless optical communication? Please help.

I want to calculate the propagation constant difference for LP01 and LP02 modes for a tapered SMF-28 (in both core and cladding).

Is there a simple formula that I can use? My goal is to see if the taper profile is adiabatic or not.

I am using this paper for my study : T. A. Birks and Y. W. Li, "The shape of fiber tapers," in Journal of Lightwave Technology, vol. 10, no. 4, pp. 432-438, April 1992, doi: 10.1109/50.134196.

equation in attached figure

In my experiment I have a double cladding fiber spliced on to a reel of SMF-28. The double cladding fiber has total cladding diameter about 2 times more than that of the SMF-28. The source is a SLD, and there is a polarization scrambler after the source which feeds onto one end of the reel of SMF-28. The output power from the 1 km long reel is X mW. But when I splice a half meter length of the specialty fiber to the reel output and measure the power it is 0.9Y mW, where Y is the power output after the polarization scrambler (Y = 3.9X). I am not sure why the power reading suddenly increased.

My set up is as follows : Elliptically polarized light at input -> Faraday Rotator -> Linear Polarizer (LP) -> Photodiode

The LP is set such that the power output is minimum. I use a lock -in-amplifier to measure the power change due to the Faraday effect. I have a more or less accurate measurement of the magnetic field and the length of the fiber. The experimental Faraday rotation (Rotation Theta= Verdet constant*MagneticField*Length of fiber) , is more than the theoretical prediction, so I was wondering if I am observing the effect of elliptical polarization at the input to the system.

As we know, when we get a type of fiber from a company, we can get a few dispersion parameter D at corresponding wavelengths( lambda).so we can also get the dispersion slope dD/d_lambda.

Then how can we get the value of 4th disperison beta_4 with the value of D and dispersion slope dD/d_lambda?

Many of the research papers I looked through have the laser or light source at one end of the fiber optic cable and a detector at the other end. But I wanted to know if there was any research on how we could transmit light through the cladding so that it propagates both ways to the two ends of the fiber optic cable?

One idea that I had was to polish off the cladding at the middle of the fiber cable so that the core is exposed. Then point the light source at the middle exposed core so that the rays pass to both ends. But I wanted to know if there was any other way to do this without altering the fiber?

I need to simulate a setup like in the attached image. The source of light is the end of an optical fiber. In order to avoid simulating the fiber, I though about using a lens with the same NA as the optical fiber.

Any ideas/suggestions are welcome!

I'm curious if anyone can share their measurement of the coupling loss as a function of the gap between two SMF FC/APC fibers at various wavelengths. If not, it would be great if you can refer me to a datasheet or a paper where this type of measurement was done.

Thanks!

Hi,

Is there any company that sell Yb-doped fiber with core diameter larger than 90 micrometer?

if anyone know please tell me about it.

Thanks.

Hello,

I'm calculating the mode overlap between my Spot Size Converter (SSC) and an optical fiber (SMF-28, NA = 0.14) in Lumerical FDTD using the Mode Expansion Monitor and Linear DFT Monitor. At the same time, I'm comparing the result with the Mode Overlap Integral of SSC (fig is attached).

The difference value is too much (~20% of difference) and I would like to know if by using the Mode Expansion Monitor the mode overlap calculation is similar to the model attached. The model attached is found in many papers and to use it I simply export the E fields calculated by Lumerical (the SSC and optical fiber E field) and import them in matlab to calculate the Mode Overlap between the fields.

Does anyone know the difference and which would be more accurate?

Thank you.

I built a optical fiber probe (one emission surrounded by six for collection, no filters) and I wish to capture Raman spectra.

The lasers I have available to me are at 976nm but they do have a lot of power (>4W), however, I don't seem to be able to measure any Raman signal.

What might I be doing wrong?

The aim is to characterize a DAS instrument connected to a fiber optic cable.

what are the properties that I should look into ? white noise ? Dynamic range? SNR ?

I did some choc tests and I'm thinking on how should I calculate the SNR. Should I calculate a SNR for different frequency band ?

Thank you in advance,

If I reduce the dimensions of an optical fiber through a tapering process, I expect high losses of confinement. I am wondering:

1) If I recoat the fiber (after the tapering process) with a low-index external coating (lower refractive index with respect to the cladding refractive index), will I expect high internal reflections?

2) Otherwise, due to the extinction coefficient of the coating, could I consider the power losses absorbed by it?

What is the right behavior of external fiber coating?

I tried methylene chloride and chloroform for several days, but they didn't work.

The information of optical ferrule and optical fiber:

We are measuring vegetation (grassland canopy) reflectance with a handheld spectrometer, using the sun as the light source. When taking white reference measurement Is it important that the distance from the optical fiber to the white reference standard is the same as the distance from the optical fiber to the sample (grassland canopy)?

Eg. Our optical fiber has a 30 degrees field of view (FOV), which would mean a ground footprint of about 0.25 square meters when holding the optical fiber at about 1m above the grassland canopy. We can use a small diameter ( 50 mm) white reference standard held close to the optical fiber end (to cover the whole FOV) or we could get a large diameter white reference standard (wide enough to cover the 0.25 square meters FOV) that we hold at grassland canopy level- 1m below the optical fiber.

I was searching for a bragg Grating simulation example in comsol, but I did not find any. The only one that I found was incomplete. Does anyone have a Bragg Grating simulation example in comsol? It can be the file or even a tutorial of the simulation.

How would the spectrometer signal change if the target molecule was well dispersed in a solution and placed on the fiber optic SPR cable VS the target molecule concentrated at a specific region on the fiber optic cable?

I am using a Blue-Wave spectrometer with an optic fiber that has a field of view (FOV) of 30 degrees to measure the reflectance of the crop canopy.

If I hold the fiber optic cable approximately at 1.25 m above the canopy for reflectance measurements, I have a ground footprint of 0.27 m in diameter.

What happens with the footprint diameter if I attach to the optic fiber a fore optic: a collimating lens (LENSQ-COL, StellarNet) that has FOV 3 degrees, an 5 mm diameter?

Does intensity of light used in OFC, effect the data rate and bandwidth provided by the OFC? If yes, should we need increase the intensities of light that is currently being used? Also by increasing intensity of light, the power and energy density carried by the light increases and does that heat up surface of the OFC (core and cladding) and should we consider such factors in improving the technology or while working with OFCs? 

I am carrying out research on MCF - MDM based optical transmission line performance analysis

The rays concentrated by convex lens is passed through 1m optical fiber. But only the ray enter into optical axis reaches fiber end, other rays are not? Can anyone suggest where i went wrong?

In our current era there is a big confusion about the usage of G.652 and G.655 optical fiber cable.

Theoretically G.655 is much better than G.652 but the operator feel that G.652 is giving almost same performance while the cost is quite less.

Anyone having direct experience please share your feedback, also I will soon be making a survey on it, so if anyone is interested in the survey then he can let me know.

Thanks.

What is the reason of the received optical signal to be slimmed down in multi-mode fiber?

I have 4 km multi-mode fiber

Dear colleagues,

We have observed large fluctuations in laser power in our setup and traced them down to fluctuations in laser beam polarisation. Attached is a schematic of the relevant part of our setup. We have experienced large fluctuations in laser intensity at the sample (after the microscope objective). Attached is a plot of laser power measured at the sample plane. We have checked the laser itself and its output power is stable. We have checked also the laser power at the exit of the optical fibre collimator (before the polarising beamsplitter) at different time points (when the power after the objective was around its maximum and when its was around its minimum) and it remains stable as well. From that we concluded that it is the plane of the polarisation that is changing in time. We have then checked the laser alone and this time placed a polariser between the laser and the power-meter. The power is still stable, showing that the polarisation of the laser output is stable in time. So there's nothing wrong with the laser itself.

Do you have any idea what could be the source of those fluctuations? I know that reflection of laser beam back to the cavity can destabilise the laser, but can this make the plane of polariation rotate? And can it happen on such a slow timescale? Thanks for your answers.

Hello dear researchers.

I want to solve a cylindrical waveguide, lick an ordinary standard optical fiber. I am familiar enough with the 2D-axis-symmetric model, but as I knew from the equations and output results (if I'm right) 2D-axis-symmetric models just solve the symmetric model in relation to the r=0 axis, and a simple revolve node, in the dataset, revolves the whole answer around the r=0 axis, and if the coordinate is not defined earlier, you may achieve only a revolved data where the data is multiplied by 2*pi.

Now, if I define a new coordinate system, particularly I mean it for electromagnetic waves, is it possible to introduce the 2D-axis-symmetric model to solve such vector-based problems properly???

Thank you in advance.

Hi. I am new to chromatic dispersion related work and have read how it affects the shape of optical pulses. I want to ask how does it work for analog continous wave laser signal? why all books only mention laser pulses and pulse broadening of digital signals. what about using analog CW laser and modulating analog IF signals on it. How will CD affect it through pulse broadening . . . secondly, books mention that CD is a linear process. Is it because the pulse broadening factor equation has only L (not L square?) because the GVD equation contains lambda square (square of wavelength or frequency). how is it a linear process then? thanks a lot

Please recommend the optimal optical component and its parameters.

Thanks a lot

Hi everybody!

I am working on my diploma thesis regarding eye endoscope. I would like to know more about the speckles in the multimode fiber. I would like to reduce speckles in MM fiber using vibration. I do not know why the vibration reduce the speckles and what happens with modes that are in the optical fiber.

Thank you for your answer!

Regards

Barbora Spurná

I would like to make an Fabry-Perot cavity without welding or adhesvie.

Hi everybody!

I am working on my diploma thesis regarding eye endoscope. I would like to know more about the origin of speckles in the multimode fiber. I suppose that the speckles depend on fiber modes but I do not know why should high-order modes move with higher speed than low-order modes. And how does this fact influence the speckles.

Thank you for your answer!

Regards

Barbora Spurná

I'm looking for a company that provides square core optical fiber at a relatively low cost. Core size I need is ideally 1000 um x 1000 um (or as close as possible). So far optoskand has it but its $475 per meter so anything less expensive than that would be decent. It doesn't need to be connectorized either just the fiber.

BER analyzer parameters meaning.

Hello,

For a special research project, we are looking for high temperature resistant optical fiber. A PPT document is attached in this mail to explain our application more precisely. Ideally, we are looking for an optical fiber that can withstand up to 1000-degree celsius.

Other specifications: - Approximate Length of optical fiber- 2m - Working temperature- 700°c- 1000°c - Approximate wavelength range - 200nm-1200nm - Mode type - Single-mode

Thanks in advance!!!!

Looking forward to your response.

Best regards, Vayalthota Gopikishore

I have a divergent beam coming from a sample in the NIR region. I need to converge the light into a fiber and take the spectrum. A rough sketch of the set up is attached here. Could some please suggest on how to select the specifications of the lenses and the optical fiber so that the emitted radiation is effectively coupled into fiber.

I am planning to concentrate the sunlight using the Fresnel lens onto the fiber optic cable for my indoor experiments. But I am thinking that I will face the following problems:

1. The aperture of the fiber optical cable is very small. Can it hold and transmit all concentrating light rays as optical cables have a particular angle of acceptance?

2. The magnitude of concentrated light is approximately 1000 x 1000 W/m2. Can the cable sustain the high temperature produced by the concentrated beam and transfer the sunlight from one place to the another?

3. What are the losses occurred in transporting the light along-with their magnitudes?

4. What is the maximum distance traveled by the concentrated light beam through the optical cable?

5. Where can I purchase the concentrated fiber optic cable from and how much does it cost (approximately)?

I will be thankful to you if you answer any of the aforementioned questions.