Create an Account  |   Log In

View All »Matching Part Numbers


Your Shopping Cart is Empty
           

Photosensitive Single Mode Fiber


Related Items










Photosensitive Single Mode Fiber

Custom Fiber Patch Cables  Optical Fiber Manufacturing

Photosensitive Single Mode Fiber

Thorlabs offers a range of photosensitive single mode fibers designed to provide high photosensitivity for UV radiation. These fibers offer low splice loss to transmission fiber and are suitable for a range of applications. Please see the table below for specifications regarding each product. We recommend T06S13 for use as a stripper tool when removing the buffer from these optical fibers in preparation for connectorization.

Item #DescriptionOperating WavelengthMode Field DiameterCut-Off
Wavelength
GF1Standard1500 - 1600 nm10.5 ± 1.0 µm at 1550 nm
9.3 ± 0.5 µm at 1310 nm
1260 ± 75 nm
GF1AAStandard1500 - 1600 nm10.5 ± 0.8 µm at 1550 nm1350 ± 100 nm
GF3Standard1500 - 1600 nm7.5 ± 0.5 µm at 1550 nm1350 ± 50 nm
GF1BLow Loss1550 nm10.4 ± 0.8 µm at 1550 nm1260 ± 100 nm
GF4ACladding Mode Offset1550 nm4.4 ± 0.2 µm at 1550 nm<1450 nm
PS1060Select Cut-Off1060 nm6.2 ± 0.8 µm at 1060 nm920 ± 50 nm
PS-PM980Polarization Maintaining980 nm6.6 ± 1.0 µm at 1550 nm900 ± 70 nm
Power Handling Limitations Imposed by Optical Fiber
Click to Enlarge
Undamaged Fiber End
Power Handling Limitations Imposed by Optical Fiber
Click to Enlarge
Damaged Fiber End

Laser Induced Damage in Optical Fibers

The following tutorial details damage mechanisms in unterminated (bare) and terminated optical fibers, including damage mechanisms at both the air-to-glass interface and within the glass of the optical fiber. Please note that while general rules and scaling relations can be defined, absolute damage thresholds in optical fibers are extremely application dependent and user specific. This tutorial should only be used as a guide to estimate the damage threshold of an optical fiber in a given application. Additionally, all calculations below only apply if all cleaning and use recommendations listed in the last section of this tutorial have been followed. For further discussion about an optical fiber’s power handling abilities within a specific application, contact Thorlabs’ Tech Support.

Damage at the Free Space-to-Fiber Interface

There are several potential damage mechanisms that can occur at the free space-to-fiber interface when coupling light into a fiber. These come into play whether the fiber is used bare or terminated in a connector.

Silica Optical Fiber Maximum Power Densities
TypeAbsolute ValuePractical Value
CW (Average Power)1 MW/cm2250 kW/cm2
10 ns Pulsed (Peak Power)5 GW/cm21 GW/cm2

Unterminated (Bare) Fiber
Damage mechanisms in bare optical fiber can be modeled similarly to bulk optics, and industry-standard damage thresholds for UV Fused Silica substrates can be applied to silica-based fiber (refer to the table to the right). The surface areas and beam diameters involved at the air-to-glass interface are extremely small compared to bulk optics, especially with single mode (SM) fiber, resulting in very small damage thresholds.

The effective area for SM fiber is defined by the mode field diameter (MFD), which is the effective cross-sectional area through which light propagates in the fiber. A free-space beam of light must be focused down to a spot of roughly 80% of this diameter to be coupled into the fiber with good efficiency. MFD increases roughly linearly with wavelength, which yields a roughly quadratic increase in damage threshold with wavelength. Additionally, a beam coupled into SM fiber typically has a Gaussian-like profile, resulting in a higher power density at the center of the beam compared with the edges, so a safety margin must be built into the calculated damage threshold value if the calculations assume a uniform density.

Multimode (MM) fiber’s effective area is defined by the core diameter, which is typically far larger than the MFD in SM fiber. Kilowatts of power can be typically coupled into multimode fiber without damage, due to the larger core size and the resulting reduced power density.

It is typically uncommon to use single mode fibers for pulsed applications with high per-pulse powers because the beam needs to be focused down to a very small area for coupling, resulting in a very high power density. It is also uncommon to use SM fiber with ultraviolet light because the MFD becomes extremely small; thus, power handling becomes very low, and coupling becomes very difficult.

Example Calculation
For SM400 single mode fiber operating at 400 nm with CW light, the mode field diameter (MFD) is approximately Ø3 µm. For good coupling efficiency, 80% of the MFD is typically filled with light. This yields an effective diameter of Ø2.4 µm and an effective area of 4.52 µm2:

Area = πr2 = π(MFD/2)2 = π • 1.22 µm2 = 4.52 µm2

This can be extrapolated to a damage threshold of 11.3 mW. We recommend using the "practical value" maximum power density from the table above to account for a Gaussian power distribution, possible coupling misalignment, and contaminants or imperfections on the fiber end face:

250 kW/cm2 = 2.5 mW/µm2

4.25 µm2 • 2.5 mW/µm2 = 11.3 mW

Terminated Fiber
Optical fiber that is terminated in a connector has additional power handling considerations. Fiber is typically terminated by being epoxied into a ceramic or steel ferrule, which forms the interfacing surface of the connector. When light is coupled into the fiber, light that does not enter the core and propagate down the fiber is scattered into the outer layers of the fiber, inside the ferrule.

The scattered light propagates into the epoxy that holds the fiber in the ferrule. If the light is intense enough, it can melt the epoxy, causing it to run onto the face of the connector and into the beam path. The epoxy can be burned off, leaving residue on the end of the fiber, which reduces coupling efficiency and increases scattering, causing further damage. The lack of epoxy between the fiber and ferrule can also cause the fiber to be decentered, which reduces the coupling efficiency and further increases scattering and damage.

The power handling of terminated optical fiber scales with wavelength for two reasons. First, the higher per photon energy of short-wavelength light leads to a greater likelihood of scattering, which increases the optical power incident on the epoxy near the end of the connector. Second, shorter-wavelength light is inherently more difficult to couple into SM fiber due to the smaller MFD, as discussed above. The greater likelihood of light not entering the fiber’s core again increases the chance of damaging scattering effects. This second effect is not as common with MM fibers because their larger core sizes allow easier coupling in general, including with short-wavelength light.

Fiber connectors can be constructed to have an epoxy-free air gap between the optical fiber and ferrule near the fiber end face. This design feature, commonly used with multimode fiber, allows some of the connector-related damage mechanisms to be avoided. Our high-power multimode fiber patch cables use connectors with this design feature.

Combined Damage Thresholds
As a general guideline, for short-wavelength light at around 400 nm, scattering within connectors typically limits the power handling of optical fiber to about 300 mW. Note that this limit is higher than the limit set by the optical power density at the fiber tip. However, power handing limitations due to connector effects do not diminish as rapidly with wavelength when compared to power density effects. Thus, a terminated fiber’s power handling is "connector-limited" at wavelengths above approximately 600 nm and is "fiber-limited" at lower wavelengths.

The graph to the right shows the power handling limitations imposed by the fiber itself and a surrounding connector. The total power handling of a terminated fiber at a given wavelength is limited by the lower of the two limitations at that wavelength. The fiber-limited (blue) line is for SM fibers. An equivalent line for multimode fiber would be far above the SM line on the Y-axis. For terminated multimode fibers, the connector-limited (red) line always determines the damage threshold.

Please note that the values in this graph are rough guidelines detailing estimates of power levels where damage is very unlikely with proper handling and alignment procedures. It is worth noting that optical fibers are frequently used at power levels above those described here. However, damage is likely in these applications. The optical fiber should be considered a consumable lab supply if used at power levels above those recommended by Thorlabs.

Damage Within Optical Fibers

In addition to damage mechanisms at the air-to-glass interface, optical fibers also display power handling limitations due to damage mechanisms within the optical fiber itself. Two categories of damage within the fiber are damage from bend losses and damage from photodarkening.

Bend Losses
Bend losses occur when a fiber is bent to a point where light traveling in the core is incident on the core/cladding interface at an angle higher than the critical angle, making total internal reflection impossible.Under these circumstances, light escapes the fiber, often in one localized area. The light escaping the fiber typically has a high power density, which can cause burns to the fiber as well as any surrounding furcation tubing.

A special category of optical fiber, called double-clad fiber, can reduce the risk of bend-loss damage by allowing the fiber’s cladding (2nd layer) to also function as a waveguide in addition to the core. By making the critical angle of the cladding/coating interface higher than the critical angle of the core/clad interface, light that escapes the core is loosely confined within the cladding. It will then leak out over a distance of centimeters or meters instead of at one localized spot within the fiber, minimizing damage. Thorlabs manufactures and sells 0.22 NA double-clad multimode fiber, which boasts very high, megawatt range power handling.

Photodarkening
A second damage mechanism within optical fiber, called photodarkening or solarization, typically occurs over time in fibers used with ultraviolet or short-wavelength visible light. The pure silica core of standard multimode optical fiber can transmit ultraviolet light, but the attenuation at these short wavelengths increases with the time exposed to the light. The mechanism that causes photodarkening is largely unknown, but several strategies have been developed to combat it. Fibers with a very low hydroxyl ion (OH) content have been found to resist photodarkening. Other dopants, including fluorine, can also reduce photodarkening.

Germanium-doped silica, which is commonly used for the core of single mode fiber for red or IR wavelengths, can experience photodarkening with blue visible light. Thus, pure silica core single mode fibers are typically used with short wavelength visible light. Single mode fibers are typically not used with UV light due to the small MFD at these wavelengths, which makes coupling extremely difficult.

Even with the above strategies in place, all fibers eventually experience photodarkening when used with UV light, and thus, fibers used with these wavelengths should be considered consumables.

Tips for Maximizing an Optical Fiber's Power Handling Capability

With a clear understanding of the power-limiting mechanisms of an optical fiber, strategies can be implemented to increase a fiber’s power handling capability and reduce the risk of damage in a given application. All of the calculations above only apply if the following strategies are implemented.

One of the most important aspects of a fiber’s power-handling capability is the quality of the end face. The end face should be clean and clear of dirt and other contaminants that can cause scattering of coupled light. Additionally, if working with bare fiber, the end of the fiber should have a good quality cleave, and any splices should be of good quality to prevent scattering at interfaces.

The alignment process for coupling light into optical fiber is also important to avoid damage to the fiber. During alignment, before optimum coupling is achieved, light may be easily focused onto parts of the fiber other than the core. If a high power beam is focused on the cladding or other parts of the fiber, scattering can occur, causing damage.

Additionally, terminated fibers should not be plugged in or unplugged while the light source is on, again so that focused beams of light are not incident on fragile parts of the connector, possibly causing damage.

Bend losses, discussed above, can cause localized burning in an optical fiber when a large amount of light escapes the fiber in a small area. Fibers carrying large amounts of light should be secured to a steady surface along their entire length to avoid being disturbed or bent.

Additionally, choosing an appropriate optical fiber for a given application can help to avoid damage. Large-mode-area fibers are a good alternative to standard single mode fibers in high-power applications. They provide good beam quality with a larger MFD, thereby decreasing power densities. Standard single mode fibers are also not generally used for ultraviolet applications or high-peak-power pulsed applications due to the high spatial power densities these applications present.

Loading Tag Cloud Loading...

Please Give Us Your Feedback
 
Email   Feedback On
(Optional)
Contact Me:
Your email address will NOT be displayed.
 
 
Please type the following key into the field to submit this form:
Click Here if you can not read the security code.
This code is to prevent automated spamming of our site
Thank you for your understanding.
  
 
Would this product be useful to you?       Little Use   1 2 3 4Very Useful

Enter Comments Below:
 
Characters remaining 8000    
Posted Comments:
Poster: aldergazly
Posted Date: 2013-12-27 01:47:59.9
we need fiber Bragg grating in the range 400-700nm
Poster: pbui
Posted Date: 2014-01-02 04:05:47.0
Response from Phong at Thorlabs: Thank you for your interest. We offer a variety of fibers that are specifically designed for use in writing fiber Bragg gratings, but we do not yet carry one with a 400-700 nm design wavelength in our catalog. We will contact you directly to discuss your requirements and to see if we can offer a suitable fiber solution.
Poster: vtgopakumar111
Posted Date: 2013-02-16 03:58:19.787
Sir/Madam What is the Neff(Effective refractive index) of the fiber @ 1550nm or the entire C band Thanks VT Gopakumar
Poster: cdaly
Posted Date: 2013-02-20 19:59:00.0
Response from Chris at Thorlabs: Thank you for your feedback. The effective index of the GF1 fiber is 1.469 at 1310 nm and 1.470 at 1550 nm.
Poster: jlow
Posted Date: 2012-11-08 14:07:00.0
Response from Jeremy at Thorlabs: We do not have data for the attenuation for the GF1. As an estimate, it would be on the order of tens of dB/km at 1550nm. The attenuation is relatively large because of the heavy doping but the typical length used is a few meters so the attenuation is not a big concern.
Poster: soonlink
Posted Date: 2012-11-01 05:58:36.187
Could you give me the data of the attenuation @1550 nm ( dB/Km ) for this kind of photosensitive fiber ?
Click on any phrase below to search our site using our new Search Engine:
fiber   lucent fiber   nufern   optical fiber   photosensitive   photosensitive fiber   photosensitive optical fiber  
Photosensitive Optical Fiber
  Enhanced Photosensitivity
  Low Splice Loss to Transmission Fibers

These general purpose photosensitive fibers are highly sensitive to UV radiation and are modematched to SMF-28e. These fibers are designed to reduce FBG writing times associated with industry standard telecommunication fiber and can be easily spliced to industry standard fiber as well.

We recommend T06S13 for use as a stripper tool when removing the buffer from these optical fibers in preparation for connectorization.

Item #Operating
Wavelength
MFD
@ 1310 nm
MFD
@ 1550 nm
CladdingCoatingCut-Off
Wavelength
NA
GF1 1500 - 1600 nm 9.3 ± 0.5 µm 10.5 ± 1.0 µm 125 ± 1.5 µm 250 ± 20 µm 1260 ± 75 nm 0.13
GF1AA 1500 - 1600 nm - 10.5 ± 0.8 µm 125 ± 1.5 µm 250 ± 20 µm 1350 ± 100 nm 0.13
GF3 1500 - 1600 nm - 8.3 ± 0.8 µm 125 ± 1.5 µm 250 ± 20 µm 1350 ± 50 nm 0.16
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
GF1 Support Documentation
GF1 Photosensitive SM, 1500 - 1600 nm, 10.5 µm MFD, 0.13 NA
$7.15
Per Meter
Volume Pricing
Today
GF1AA Support Documentation
GF1AA Photosensitive SM, 1500 - 1600 nm, 10.5 µm MFD, 0.13 NA
$19.80
Per Meter
Volume Pricing
Today
GF3 Support Documentation
GF3 Photosensitive SM, 1500 - 1600 nm, 8.3 µm MFD, 0.16 NA
$30.00
Per Meter
Volume Pricing
Today
Select Cut-Off Photosensitive Fiber
  High Photosensitivity
  Low Splice Loss to Transmission Fiber
  Low Cost, High Yield Grating Fabrication

The PS1060 photosensitive fiber is designed to provide high photosensitivity to UV radiation. This fiber is specifically designed for use in writing fiber Bragg gratings for pump stabilizers or diode output wavelengths in the 980 to 1060nm range. PS1060 may also be used in coupler applications.

We recommend T06S13 for use as a stripper tool when removing the buffer from these optical fibers in preparation for connectorization.

Item #Operating WavelengthMFD @ 1060 nmCladdingCoatingCut-Off
Wavelength
NA
PS1060 980 - 1060 nm 6.2 ± 0.8 µm 125 ± 1.5 µm 245 ± 15 µm 920 ± 50 nm 0.13
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
PS1060 Support Documentation
PS1060 Photosensitive Select Cut-Off Fiber, 1060 nm Design Wavelength
$11.40
Per Meter
Volume Pricing
Today
Low Loss Photosensitive Fiber
  Low Background Attenuation
  Splice Compatible with SMF-28e
  UV Photo-Sensitive

The low-loss photosensitive fiber provides much higher photosensitivity than standard transmission fibers to UV radiation. This fiber is specifically designed to be splice compatible with SMF-28e and may be used in WDM applications. The reduced attenuation allows the fiber to be used in longer lengths and reduces the insertion loss in manufactured fiber optic components.

We recommend T06S13 for use as a stripper tool when removing the buffer from these optical fibers in preparation for connectorization.

Item #Operating WavelengthMFD @ 1550 nmCladdingCoatingCut-Off
Wavelength
NA
GF1B 1550 nm 10.4 ± 0.8 µm 125 ± 1.0 µm 245 ± 15 µm 1260 ± 100 nm 0.13
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
GF1B Support Documentation
GF1B Low Loss Photosensitive Fiber, 1550nm Design Wavelength
$6.10
Per Meter
Volume Pricing
Today
Cladding Mode Offset Photosensitive Fiber
  High Photosensitivity
  High Cladding Mode Offset 9 nm
  Tight Tolerances

The Cladding Mode Offset Fiber is designed specifically with improved cladding mode offset. The cladding mode offset operation enhances the fiber's performance when writing two or more gratings adjacent to each other (9 nm offset typical). Cladding Mode Offset fibers exhibit low splice loss to the industry standard telecommunications fiber.

We recommend T06S13 for use as a stripper tool when removing the buffer from these optical fibers in preparation for connectorization.

Item #Operating WavelengthMFD @ 1550 nmCladdingCoatingCut-Off
Wavelength
NA
GF4A 1550 nm 4.4 ± 0.2 µm 125 ± 1.5 µm 250 ± 20 µm 1450 nm 0.13
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
GF4A Support Documentation
GF4A Cladding Mode Offset Photosensitive Fiber, 1550nm Design Wavelength
$19.60
Per Meter
Volume Pricing
Today
Polarization Maintaining Photosensitive Fiber
  Low Attenuation
  All PM Attrributes with Enhanced Photosensitivity
  High Lot-to-Lot Uniformity

Designed for use in 980 nm pump lasers diodes, couplers and multiplexers, PS-PM980 offers enhanced photosensitivity that substantially reduces writing times as well as excellent polarization maintaining attributes.

We recommend T06S13 for use as a stripper tool when removing the buffer from these optical fibers in preparation for connectorization.

Item #Operating WavelengthMFD @ 980 nmCladdingCoatingCut-Off
Wavelength
PS-PM980 980 nm 6.6 ± 1.0 µm 125 ± 1.5 µm 245 ± 15 µm 900 ± 70 nm
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
PS-PM980 Support Documentation
PS-PM980 PM Photosensitive Fiber, 980 nm Design Wavelength
$30.70
Per Meter
Volume Pricing
Today
Log In   |   My Account  |   Contact Us  |   Privacy Policy  |   Home  |   Site Index
Regional Websites: East Coast US US | Europe | Asia | China | Japan
Copyright 1999-2014 Thorlabs, Inc.
Sales: 1-973-579-7227
Technical Support: 1-973-300-3000


High Quality Thorlabs Logo 1000px: Save this Image