Laser-Induced Damage in Silica Optical Fibers

The following tutorial details damage mechanisms relevant to unterminated (bare) fiber, terminated optical fiber, and other fiber components from laser light sources. These mechanisms include damage that occurs at the air / glass interface (when free-space coupling or when using connectors) and in the optical fiber itself. A fiber component, such as a bare fiber, patch cable, or fused coupler, may have multiple potential avenues for damage (e.g., connectors, fiber end faces, and the device itself). The maximum power that a fiber can handle will always be limited by the lowest limit of any of these damage mechanisms.

While the damage threshold can be estimated using scaling relations and general rules, absolute damage thresholds in optical fibers are very application dependent and user specific. Users can use this guide to estimate a safe power level that minimizes the risk of damage. Following all appropriate preparation and handling guidelines, users should be able to operate a fiber component up to the specified maximum power level; if no maximum is specified for a component, users should abide by the "practical safe level" described below for safe operation of the component. Factors that can reduce power handling and cause damage to a fiber component include, but are not limited to, misalignment during fiber coupling, contamination of the fiber end face, or imperfections in the fiber itself. For further discussion about an optical fiber’s power handling abilities for a specific application, please contact Thorlabs’ Tech Support.

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Undamaged Fiber End

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Damaged Fiber End

Damage at the Air / Glass Interface

There are several potential damage mechanisms that can occur at the air / glass interface. Light is incident on this interface when free-space coupling or when two fibers are mated using optical connectors. High-intensity light can damage the end face leading to reduced power handling and permanent damage to the fiber. For fibers terminated with optical connectors where the connectors are fixed to the fiber ends using epoxy, the heat generated by high-intensity light can burn the epoxy and leave residues on the fiber facet directly in the beam path.

Damage Mechanisms on the Bare Fiber End Face

Damage mechanisms on a fiber end face can be modeled similarly to bulk optics, and industry-standard damage thresholds for UV Fused Silica substrates can be applied to silica-based fiber. However, unlike bulk optics, the relevant surface areas and beam diameters involved at the air / glass interface of an optical fiber are very small, particularly for coupling into single mode (SM) fiber. therefore, for a given power density, the power incident on the fiber needs to be lower for a smaller beam diameter.

The table to the right lists two thresholds for optical power densities: a theoretical damage threshold and a "practical safe level". In general, the theoretical damage threshold represents the estimated maximum power density that can be incident on the fiber end face without risking damage with very good fiber end face and coupling conditions. The "practical safe level" power density represents minimal risk of fiber damage. Operating a fiber or component beyond the practical safe level is possible, but users must follow the appropriate handling instructions and verify performance at low powers prior to use.

Calculating the Effective Area for Single Mode and Multimode Fibers
The effective area for single mode (SM) fiber is defined by the mode field diameter (MFD), which is the cross-sectional area through which light propagates in the fiber; this area includes the fiber core and also a portion of the cladding. To achieve good efficiency when coupling into a single mode fiber, the diameter of the input beam must match the MFD of the fiber.

As an example, SM400 single mode fiber has a mode field diameter (MFD) of ~Ø3 µm operating at 400 nm, while the MFD for SMF-28 Ultra single mode fiber operating at 1550 nm is Ø10.5 µm. The effective area for these fibers can be calculated as follows:

SM400 Fiber: Area = Pi x (MFD/2)² = Pi x (1.5 µm)² = 7.07 µm² = 7.07 x 10^-8 cm²

 SMF-28 Ultra Fiber: Area = Pi x (MFD/2)² = Pi x (5.25 µm)² = 86.6 µm² = 8.66 x 10^-7 cm²

To estimate the power level that a fiber facet can handle, the power density is multiplied by the effective area. Please note that this calculation assumes a uniform intensity profile, but most laser beams exhibit a Gaussian-like shape within single mode fiber, resulting in a higher power density at the center of the beam compared to the edges. Therefore, these calculations will slightly overestimate the power corresponding to the damage threshold or the practical safe level. Using the estimated power densities assuming a CW light source, we can determine the corresponding power levels as:

SM400 Fiber: 7.07 x 10^-8 cm² x 1 MW/cm² = 7.1 x 10^-8 MW = 71 mW (Theoretical Damage Threshold)
     7.07 x 10^-8 cm² x 250 kW/cm² = 1.8 x 10^-5 kW = 18 mW (Practical Safe Level)

SMF-28 Ultra Fiber: 8.66 x 10^-7 cm² x 1 MW/cm² = 8.7 x 10^-7 MW = 870 mW (Theoretical Damage Threshold)
           8.66 x 10^-7 cm² x 250 kW/cm² = 2.1 x 10^-4 kW = 210 mW (Practical Safe Level)

The effective area of a multimode (MM) fiber is defined by the core diameter, which is typically far larger than the MFD of an SM fiber. For optimal coupling, Thorlabs recommends focusing a beam to a spot roughly 70 - 80% of the core diameter. The larger effective area of MM fibers lowers the power density on the fiber end face, allowing higher optical powers (typically on the order of kilowatts) to be coupled into multimode fiber without damage.

Damage Mechanisms Related to Ferrule / Connector Termination

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Plot showing approximate input power that can be incident on a single mode silica optical fiber with a termination. Each line shows the estimated power level due to a specific damage mechanism. The maximum power handling is limited by the lowest power level from all relevant damage mechanisms (indicated by a solid line).

Fibers terminated with optical connectors have additional power handling considerations. Fiber is typically terminated using epoxy to bond the fiber to a ceramic or steel ferrule. When light is coupled into the fiber through a connector, light that does not enter the core and propagate down the fiber is scattered into the outer layers of the fiber, into the ferrule, and the epoxy used to hold the fiber in the ferrule. If the light is intense enough, it can burn the epoxy, causing it to vaporize and deposit a residue on the face of the connector. This results in localized absorption sites on the fiber end face that reduce coupling efficiency and increase scattering, causing further damage.

For several reasons, epoxy-related damage is dependent on the wavelength. In general, light scatters more strongly at short wavelengths than at longer wavelengths. Misalignment when coupling is also more likely due to the small MFD of short-wavelength SM fiber that also produces more scattered light.

To minimize the risk of burning the epoxy, fiber connectors can be constructed to have an epoxy-free air gap between the optical fiber and ferrule near the fiber end face. Our high-power multimode fiber patch cables use connectors with this design feature.

Determining Power Handling with Multiple Damage Mechanisms

When fiber cables or components have multiple avenues for damage (e.g., fiber patch cables), the maximum power handling is always limited by the lowest damage threshold that is relevant to the fiber component. In general, this represents the highest input power that can be incident on the patch cable end face and not the coupled output power.

As an illustrative example, the graph to the right shows an estimate of the power handling limitations of a single mode fiber patch cable due to damage to the fiber end face and damage via an optical connector. The total input power handling of a terminated fiber at a given wavelength is limited by the lower of the two limitations at any given wavelength (indicated by the solid lines). A single mode fiber operating at around 488 nm is primarily limited by damage to the fiber end face (blue solid line), but fibers operating at 1550 nm are limited by damage to the optical connector (red solid line).

In the case of a multimode fiber, the effective mode area is defined by the core diameter, which is larger than the effective mode area for SM fiber. This results in a lower power density on the fiber end face and allows higher optical powers (on the order of kilowatts) to be coupled into the fiber without damage (not shown in graph). However, the damage limit of the ferrule / connector termination remains unchanged and as a result, the maximum power handling for a multimode fiber is limited by the ferrule and connector termination. 

Please note that these are rough 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, these applications typically require expert users and testing at lower powers first to minimize risk of damage. Even still, optical fiber components should be considered a consumable lab supply if used at high power levels.

Intrinsic Damage Threshold

In addition to damage mechanisms at the air / glass interface, optical fibers also display power handling limitations due to damage mechanisms within the optical fiber itself. These limitations will affect all fiber components as they are intrinsic to the 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 a localized area. The light escaping the fiber typically has a high power density, which burns the fiber coating 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 the risk of 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, called photodarkening or solarization, can occur in fibers used with ultraviolet or short-wavelength visible light, particularly those with germanium-doped cores. Fibers used at these wavelengths will experience increased attenuation over time. The mechanism that causes photodarkening is largely unknown, but several fiber designs have been developed to mitigate it. For example, fibers with a very low hydroxyl ion (OH) content have been found to resist photodarkening and using other dopants, such as fluorine, can also reduce photodarkening.

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

Preparation and Handling of Optical Fibers

General Cleaning and Operation Guidelines
These general cleaning and operation guidelines are recommended for all fiber optic products. Users should still follow specific guidelines for an individual product as outlined in the support documentation or manual. Damage threshold calculations only apply when all appropriate cleaning and handling procedures are followed.

1. All light sources should be turned off prior to installing or integrating optical fibers (terminated or bare). This ensures that focused beams of light are not incident on fragile parts of the connector or fiber, which can possibly cause damage.

2. The power-handling capability of an optical fiber is directly linked to the quality of the fiber/connector end face. Always inspect the fiber end prior to connecting the fiber to an optical system. The fiber end face should be clean and clear of dirt and other contaminants that can cause scattering of coupled light. Bare fiber should be cleaved prior to use and users should inspect the fiber end to ensure a good quality cleave is achieved.

3. If an optical fiber is to be spliced into the optical system, users should first verify that the splice is of good quality at a low optical power prior to high-power use. Poor splice quality may increase light scattering at the splice interface, which can be a source of fiber damage.

4. Users should use low power when aligning the system and optimizing coupling; this minimizes exposure of other parts of the fiber (other than the core) to light. Damage from scattered light can occur if a high power beam is focused on the cladding, coating, or connector.

Tips for Using Fiber at Higher Optical Power
Optical fibers and fiber components should generally be operated within safe power level limits, but under ideal conditions (very good optical alignment and very clean optical end faces), the power handling of a fiber component may be increased. Users must verify the performance and stability of a fiber component within their system prior to increasing input or output power and follow all necessary safety and operation instructions. The tips below are useful suggestions when considering increasing optical power in an optical fiber or component.

1. Splicing a fiber component into a system using a fiber splicer can increase power handling as it minimizes possibility of air/fiber interface damage. Users should follow all appropriate guidelines to prepare and make a high-quality fiber splice. Poor splices can lead to scattering or regions of highly localized heat at the splice interface that can damage the fiber.

2. After connecting the fiber or component, the system should be tested and aligned using a light source at low power. The system power can be ramped up slowly to the desired output power while periodically verifying all components are properly aligned and that coupling efficiency is not changing with respect to optical launch power.

3. Bend losses that result from sharply bending a fiber can cause light to leak from the fiber in the stressed area. When operating at high power, the localized heating that can occur when a large amount of light escapes a small localized area (the stressed region) can damage the fiber. Avoid disturbing or accidently bending fibers during operation to minimize bend losses.

4. Users should always choose the appropriate optical fiber for a given application. For example, large-mode-area fibers are a good alternative to standard single mode fibers in high-power applications as they provide good beam quality with a larger MFD, decreasing the power density on the air/fiber interface.

5. Step-index silica single mode fibers are normally not used for ultraviolet light or high-peak-power pulsed applications due to the high spatial power densities associated with these applications.

Optogenetics Selection Guide

Thorlabs offers a wide range of optogenetics components; the compatibility of these products in select standard configurations is discussed in detail here. Please contact Technical Support for assistance with items outside the scope of this guide, including custom fiber components for optogenetics.

Single-Site Stimulation

One Light Source to One Cannula Implant

The most straightforward method for in vivo light stimulation of a specimen is to use a single fiber optic with a single LED light source. The single wavelength LED is powered by an LED driver, and then the illumination output is fiber-coupled into a patch cable, which connects to the implanted cannula. See the graphics and expandable compatibility tables below for the necessary patch cables and cannulae to create this setup. To choose the appropriate LED and driver, see below or the full web presentation.

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Click to See Ø1.25 mm (LC) Ferrule Compatible Patch Cables, Cannulae, and Interconnects

Component Selection Table (Click Links for Item Description Popup)
Fiber Type		FG105LCA	FG200UCC	FT200EMT	FP200URT	FT400EMT	FP400URT
Fiber Type Specs	Core Diameter	105 µm	200 µm			400 µm
	Wavelength Range	400 - 2400 nm	250 - 1200 nm	400 - 2200 nm	300 - 1200 nm	400 - 2200 nm	300 - 1200 nm
	NA	0.22	0.22	0.39	0.50	0.39	0.50
Patch Cablesb	Standard FC/PC Input	M61L01	M86L005 M86L01	M83L01 MR83L01	M73L01	M99L01	M127L01
	Standard SMA905 Input	M63L01	M87L005 M87L01	M89L01 MR89L01	M95L01	M98L01	M125L01
	Rotary Joint FC/PC Input	-	-	RJPFL2	-	RJPFL4	-
	Rotary Joint SMA905 Input	-	-	RJPSL2	-	RJPSL4	-
Compatible Mating Sleeve/Interconnect		ADAL1, ADAL3, or ADAL4-5
Fiber Optic Cannulaec	Ceramic 6.4 mm Long Ferrule	CFMLC21L02 CFMLC21L05 CFMLC21L10 CFMLC21L20 CFMLC21U-20	CFMLC22L02 CFMLC22L05 CFMLC22L10 CFMLC22L20 CFMLC22U-20	CFMLC12L02 CFMLC12L05 CFMLC12L10 CFMLC12L20 CFMLC12U-20	CFMLC52L02 CFMLC52L05 CFMLC52L10 CFMLC52L20 CFMLC52U-20	CFMLC14L02 CFMLC14L05 CFMLC14L10 CFMLC14L20 CFMLC14U-20	CFMLC15L02 CFMLC15L05 CFMLC15L10 CFMLC15L20
	Diffuser Tip (Ceramic 6.4 mm Long Ferrule)	-	-	CFDSB02 CFDSB05 CFDSB10 CFDSB20	-	-	-
	Ceramic 10.5 mm Long Ferrule	-	CFMXA02 CFMXA05 CFMXA10 CFMXA20	CFMXB02 CFMXB05 CFMXB10 CFMXB20	CFMXC02 CFMXC05 CFMXC10 CFMXC20	-	CFMXD02 CFMXD05 CFMXD10 CFMXD20
	Stainless Steel 6.4 mm Long Ferrule	CFML21L02 CFML21L05 CFML21L10 CFML21L20 CFML21U-20	CFML22L02 CFML22L05 CFML22L10 CFML22L20 CFML22U-20	CFML12L02 CFML12L05 CFML12L10 CFML12L20 CFML12U-20	CFML52L02 CFML52L05 CFML52L10 CFML52L20 CFML52U-20	CFML14L02 CFML14L05 CFML14L10 CFML14L20 CFML14U-20	CFML15L02 CFML15L05 CFML15L10 CFML15L20
Items are compatible with each other when they are comprised of the same fiber type and listed in the same column. Patch cables for single source to single implant applications are highlighted in green above. Choose a patch cable with an input that matches your light source. Available cannulae are highlighted in orange of the table above. Cannulae within the same column are interchangeable.

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Click to See Ø2.5 mm (FC) Ferrule Compatible Patch Cables, Cannulae, and Interconnects

Component Selection Table (Click Links for Item Description Popup)
Fiber Type		FG200UCC	FT200EMT	FP200URT	FT300EMT	FT400EMT	FP400URT
Fiber Type Specs	Core Diameter	200 µm			300 µm	400 µm
	Wavelength Range	250 - 1200 nm	400 - 2200 nm	300 - 1200 nm	400 - 2200 nm	400 - 2200 nm	300 - 1200 nm
	NA	0.22	0.39	0.50	0.39	0.39	0.50
Patch Cablesb	Standard FC/PC Input	M80L005 M80L01	M81L005 M81L01 MR81L01	M104L01	M56L005 M56L01	M82L005 M82L01	M128L01
	Standard SMA905 Input	M84L005 M84L01	M77L005 M77L01 MR77L01	M106L01	M58L005 M58L01	M79L005 M79L01	M126L01
	Rotary Joint FC/PC Input	-	RJAFF2 RJPFF2	-	-	RJPFF4	-
	Rotary Joint SMA905 Input	-	RJASF2 RJPSF2	-	-	RJPSF4	-
Compatible Mating Sleeve/Interconnect		ADAF1, ADAF2, or ADAF4-5
Fiber Optic Cannulaec	Ceramic 10.5 mm Long Ferrule	CFMC22L02 CFMC22L05 CFMC22L10 CFMC22L20 CFMC22U-20	CFMC12L02 CFMC12L05 CFMC12L10 CFMC12L20 CFMC12U-20	CFMC52L02 CFMC52L05 CFMC52L10 CFMC52L20 CFMC52U-20	CFMC13L02 CFMC13L05 CFMC13L10 CFMC13L20	CFMC14L02 CFMC14L05 CFMC14L10 CFMC14L20 CFMC14U-20	CFMC54L02 CFMC54L05 CFMC54L10 CFMC54L20
	Stainless Steel 12.7 mm Long Ferrule	CFM22L02 CFM22L05 CFM22L10 CFM22L20 CFM22U-20	CFM12L02 CFM12L05 CFM12L10 CFM12L20 CFM12U-20	CFM52L02 CFM52L05 CFM52L10 CFM52L20 CFM52U-20	CFM13L02 CFM13L05 CFM13L10 CFM13L20	CFM14L02 CFM14L05 CFM14L10 CFM14L20 CFM14U-20	CFM15L02 CFM15L05 CFM15L10 CFM15L20
Items are compatible with each other when they are comprised of the same fiber type and listed in the same column. Patch cables for single source to single implant applications are highlighted in green above. Choose a patch cable with an input that matches your light source. Available cannulae are highlighted in orange of the table above. Cannulae within the same column are interchangeable.

Bilateral Stimulation

The ability to accurately and simultaneously direct light to multiple locations within a specimen is desired for many types of optogenetics experiments. For example, bilateral stimulation techniques typically target neurons in two spatially separated regions in order to induce a desired behavior. In more complex experiments involving the simultaneous inhibition and stimulation of neurons, delivering light of two different monochromatic wavelengths within close proximity enables the user to perform these experiments without implanting multiple cannulae, which can increase stress on the specimen.

Bilateral stimulation can be achieved with several different configurations depending on the application requirements. The sections below illustrate examples of different configurations using Thorlabs' optogenetics products.

Option 1: One Light Source to Two Cannula Implants Using Rotary Joint Splitter

Thorlabs' RJ2 1x2 Rotary Joint Splitter is designed for optogenetics applications and is used to split light from a single input evenly between two outputs. The rotary joint interface allows connected patch cables to freely rotate, reducing the risk of fiber damage caused by a moving specimen. See the graphic and compatibility table below for the necessary cables and cannulae to create this setup. For LEDs and drivers, see below or the full web presentation.

Click for Details

Click to See Ø1.25 mm (LC) Ferrule Components Recommended for Use with RJ2 Rotary Joint Splitter

Component Selection Table (Click Links for Item Description Popup)
Common Fiber Properties
Fiber Properties	Core Diameter	200 µm			400 µm
	Wavelength Rangea	400 - 700 nm	400 - 700 nm	400 - 700 nm	400 - 700 nm	400 - 700 nm
	NA	0.22	0.39	0.50	0.39	0.50
Input Patch Cablesb	Standard FC/PC Connectors	M122L01 M122L02 M122L05	M72L01 M72L02 M72L05	M123L01 M123L02	M74L01 M74L02 M74L05	M124L01 M124L02
	Hybrid SMA905 to FC/PC	M36L01	M75L01 M75L02	M129L01 M129L02	M76L01 M76L02	M131L01 M131L02
Rotary Joint		RJ2
Output Patch Cables	FC/PC to Ø1.25 mm (LC) Ferrule	M86L005 M86L01	M83L01 MR83L01	M73L01	M99L01	M127L01
Compatible Mating Sleeve/Interconnect		ADAL1, ADAL3, or ADAL4-5
Fiber Optic Cannulaec	Ceramic 6.4 mm Long Ferrule	CFMLC22L02 CFMLC22L05 CFMLC22L10 CFMLC22L20 CFMLC22U-20	CFMLC12L02 CFMLC12L05 CFMLC12L10 CFMLC12L20 CFMLC12U-20	CFMLC52L02 CFMLC52L05 CFMLC52L10 CFMLC52L20 CFMLC52U-20	CFMLC14L02 CFMLC14L05 CFMLC14L10 CFMLC14L20 CFMLC14U-20	CFMLC15L02 CFMLC15L05 CFMLC15L10 CFMLC15L20
	Diffuser Tip (Ceramic 6.4 mm Long Ferrule)	-	CFDSB02 CFDSB05 CFDSB10 CFDSB20	-	-	-
	Ceramic 10.5 mm Long Ferrule	CFMXA02 CFMXA05 CFMXA10 CFMXA20	CFMXB02 CFMXB05 CFMXB10 CFMXB20	CFMXC02 CFMXC05 CFMXC10 CFMXC20	-	CFMXD02 CFMXD05 CFMXD10 CFMXD20
	Stainless Steel 6.4 mm Long Ferrule	CFML22L02 CFML22L05 CFML22L10 CFML22L20 CFML22U-20	CFML12L02 CFML12L05 CFML12L10 CFML12L20 CFML12U-20	CFML52L02 CFML52L05 CFML52L10 CFML52L20 CFML52U-20	CFML14L02 CFML14L05 CFML14L10 CFML14L20 CFML14U-20	CFML15L02 CFML15L05 CFML15L10 CFML15L20
Products in each column can be used with each other over the indicated wavelength range and is limited by the operating range of the RJ2 Rotary Joint Splitter. Individual products may be used outside this range; see product information for detailed specifications. Use a standard FC/PC patch cable to connect to an FC/PC-terminated light source. SMA905 to FC/PC hybrid patch cables should be used to connect to an SMA905-terminated light source. Available cannulae are highlighted in orange of the table above. Cannulae within the same column are interchangeable.

Click for Detials

Click to See Ø2.5 mm (FC) Ferrule Components Recommended for Use with RJ2 Rotary Joint Splitter

Component Selection Table (Click Links for Item Description Popup)
Common Fiber Properties
Fiber Properties	Core Diameter	200 µm			300 µm	400 µm
	Wavelength Rangea	400 - 700 nm	400 - 700 nm	400 - 700 nm	400 - 700 nm	400 - 700 nm	400 - 700 nm
	NA	0.22	0.39	0.50	0.39	0.39	0.50
Input Patch Cables	Standard FC/PC Connectors	M122L01 M122L02 M122L05	M72L01 M72L02 M72L05	M123L01 M123L02	M56L005 M56L01	M74L01 M74L02 M74L05	M124L01 M124L02
	Hybrid SMA905 to FC/PC	M36L01	M75L01 M75L02	M129L01 M129L02	M58L005 M58L01	M76L01 M76L02	M131L01 M131L02
Rotary Joint		RJ2
Output Patch Cables	FC/PC to Ø2.5 mm (FC) Ferrule	M80L005 M80L01	M81L005 M81L01 MR81L01	M104L01	M56L005 M56L01	M82L005 M82L01	M128L01
Compatible Mating Sleeve/Interconnect		ADAF1, ADAF2, or ADAF4-5
Fiber Optic Cannulaec	Ceramic 10.5 mm Long Ferrule	CFMC22L02 CFMC22L05 CFMC22L10 CFMC22L20 CFMC22U-20	CFMC12L02 CFMC12L05 CFMC12L10 CFMC12L20 CFMC12U-20	CFMC52L02 CFMC52L05 CFMC52L10 CFMC52L20 CFMC52U-20	CFMC13L02 CFMC13L05 CFMC13L10 CFMC13L20	CFMC14L02 CFMC14L05 CFMC14L10 CFMC14L20 CFMC14U-20	CFMC54L02 CFMC54L05 CFMC54L10 CFMC54L20
	Stainless Steel 12.7 mm Long Ferrule	CFM22L02 CFM22L05 CFM22L10 CFM22L20 CFM22U-20	CFM12L02 CFM12L05 CFM12L10 CFM12L20 CFM12U-20	CFM52L02 CFM52L05 CFM52L10 CFM52L20 CFM52U-20	CFM13L02 CFM13L05 CFM13L10 CFM13L20	CFM14L02 CFM14L05 CFM14L10 CFM14L20 CFM14U-20	CFM15L02 CFM15L05 CFM15L10 CFM15L20
Products in each column can be used with each other over the indicated wavelength range and is limited by the operating range of the RJ2 Rotary Joint Splitter. Individual products may be used outside this range; see product information for detailed specifications. Use a standard FC/PC patch cable to connect to an FC/PC-terminated light source. SMA905 to FC/PC hybrid patch cables should be used to connect to an SMA905-terminated light source. Available cannulae are highlighted in orange of the table above. Cannulae within the same column are interchangeable.

Option 2: One or Two Light Sources to Two Cannula Implants

If the intent is for one LED source to connect to two cannulae for simultaneous light modulation, then a bifurcated fiber bundle can be used to split the light from the LED into each respective cannula. For dual wavelength stimulation (mixing two wavelengths in a single cannula) or a more controlled split ratio between cannula, one can use a multimode coupler to connect one or two LEDs to the cannulae. If one cable end is left unused, the spare coupler cable end may be terminated by a light trap. See the graphic and compatibility table below for the necessary cables and cannulae to create this setup. For LEDs and drivers, see below or the full web presentation.

Click on Each Component Below for More Information

Two Light Sources into One Dual-Core Cannula Implant

For bilateral stimulation applications where the two cannulas need to be placed in close proximity (within ~1 mm), Thorlabs offers dual-core patch cables and cannulae that are designed for this specific application. Each core is driven by a separate light source, enabling users to stimulate and/or supress nerve cells in the same region of the specimen. See the graphic and compatibility table below for the necessary cables and cannulae to create this setup. For LEDs and drivers, see below or the full web presentation.

Click on Each Component for More Information

Popular Fiber-Coupled LEDs for Optogenetics
Item #	M470F3	M590F3
Center Wavelength	470 nm	590 nm
Bandwidth (FWHM)	20 nm	16 nm
Typical Output Spectrum (Click to Enlarge)
Ø200 µm Core Fiber Output (Typ.)a	7.0 mW	1.5 mW
Ø400 µm Core Fiber Output (Typ.)b	21.8 mW	4.6 mW
CW Drive Current (Max)	1.0 A	1.0 A
LED Forward Voltage	3.1 V	2.6 V
Typical Lifetime	>50,000 Hours	>10,000 Hours

• Tested using MM Fiber with Ø200 µm core, 0.22 NA (Item # FG200UCC).
• Tested using MM Fiber with Ø400 µm core, 0.39 NA (Item # FT400EMT).

Illumination

Click to Enlarge
M470F3

Fiber-Coupled LEDs and Drivers

Our fiber-coupled LEDs are ideal light sources for optogenetics applications. They feature a variety of wavelength choices and a convenient interconnection to optogenetics patch cables. Thorlabs offers fiber-coupled LEDs with nominal wavelengths ranging from 280 nm to 1050 nm. See the table to the right for the LEDs with the most popular wavelengths for optogenetics. A table of compatible LED drivers can be viewed by clicking below.

Click to See Compatible LED Drivers

Compatible Driversa	LEDD1Bb	DC2200c	DC4100c,d,e	DC4104c,d,e
Click Photos to Enlarge
Main Driver Features	Very Compact Footprint 60 mm x 73 mm x 104 mm (W x H x D)	Touchscreen Interface with Internal and External Options for Pulsed and Modulated LED Operation	4 Channelsd	4 Channelsd
LED Driver Current Output (Max)	1.2 A	LED1 Terminal: 10.0 A LED2 Terminal: 2.0 Af	1.0 A per Channel	1.0 A per Channel
LED Driver Forward Voltage (Max)	12 V	50 V	5 V	5 V
Modulation Frequency	0 to 5 kHz (External)	20 to 100 kHz (Internal)h DC to 250 kHz (External)g,h	0 to 100 kHz (External)h Simultaneous Across all Channels	0 to 100 kHz (External)h Independently Controlled Channels
External Control Interface(s)	Analog (BNC)	USB 2.0 and Analog (BNC)	USB 2.0 and Analog (BNC)	USB 2.0 and Analog (8-Pin)
EEPROM Compatible: Reads Out LED Data for LED Settings	-
LCD Display	-

• Click on the item number link to view the complete presentation for each controller.
• The preferred power supply (single channel or hub-based) depends on the end user's application and whether you already own compatible power supplies. To that end and in keeping with Thorlabs' green initiative, we do not ship the LEDD1B bundled with a power supply. This avoids the cost and inconvenience of receiving an unwanted single-channel supply if a hub-based system (Item # KCH301 or KCH601) would be more appropriate.
• Automatically limits to LED's max current via EEPROM readout.
• The DC4100 and DC4104 can power and control up to four LEDs simultaneously when used with the DC4100-HUB. The fiber-coupled LEDs on this page all require the DC4100-HUB when used with the DC4100 or DC4104.
• These LED drivers have a maximum forward voltage rating of 5 V and can provide a maximum current of 1000 mA. As a result, they cannot be used to drive LEDs which have forward voltage ratings greater than 5 V. LEDs with maximum current ratings higher than 1.0 A can be driven using this driver, but will not reach full power.
• The fiber-coupled LEDs sold above are compatible with the LED2 Terminal.
• Small Signal Bandwidth: Modulation not exceeding 20% of full scale current. The driver accepts other waveforms, but the maximum frequency will be reduced.
• The M565F3 and M595F2 LEDs produce light by stimulating emission from phosphor, which limits their modulation frequency range. These LEDs may not turn off completely when modulated above 10 kHz at duty cycles below 50%.