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Optogenetics Bifurcated Fiber Bundles: 2 Fibers![]()
BFYL2LS01 Ø1.25 mm Ceramic Ferrules, Ø1.25 mm Ceramic Ferrule Ø2.5 mm Ceramic Ferrule Common Connector Face
Two Ø400 µm Core Fibers ![]() Please Wait ![]() Click for Details All Fiber Optic Cannulae and Optogenetics Patch Cables can be easily mated using an Interconnect or Mating Sleeve. Features
These Bifurcated Multimode Fiber Optic Cables, also known as Y-cables, are ideal for use in optogenetics experiments that require simultaneous in vivo stimulation. The ceramic ferrules are compatible with our implantable fiber optic cannulae, while the SMA905 or FC/PC connector can be connected to a light source, such as our Fiber-Coupled LEDs with SMA connectors or multimode fiber-coupled laser source, respectively. These patch cables feature fiber with either a Ø200 µm (0.22 or 0.39 NA) or Ø400 µm core (0.39 NA). The fiber legs are covered with a thin, approximately Ø1.4 mm, outer heat-shrink tubing that protects the fiber and minimizes cable mass to reduce the stress on the specimen. Cables with Ø1.25 mm ferrules can be easily connected to Ø1.25 mm fiber optic cannulae using the ADAL1 mating sleeve or ADAL3 interconnect. Cables with Ø2.5 mm ferrules can be easily connected to Ø2.5 mm fiber optic cannulae using the ADAF1 mating sleeve or ADAF2 interconnect. Each patch cable includes three protective caps that shield the ferrule ends and common connector from dust and other hazards when not in use. Additional fiber caps are also sold separately. If the fiber ends become dirty from use, we offer a selection of inspection tools, including the FS201 Fiber Inspection Scope, as well as fiber optic cleaning products. Ferrule Size and Fiber Core Size Custom fiber bundles are available upon request, including straight bundles and bifurcated fiber bundles with one common connector split into two or more connectors. See the Custom Bundles tab for an overview of some of our custom bundle capabilities. Please contact Tech Support for details. ![]() Click to Enlarge Multiple fiber NAs are available across our optogenetics product line; cannulae with a 0.22 or 0.39 NA are sold on this page. Mating Sleeve and Patch Cable Compatibility The other end of the fiber bundle has an SMA905 or FC/PC connector for interfacing with other components, such as our Fiber-Coupled LEDs with SMA connectors. The two cores in the bifurcated bundles will not be illuminated if connected to a fiber-coupled laser source; therefore, for dual cannula studies using our S1FC473MM 473 nm multimode fiber-coupled laser source, we recommend using a 2x2 multimode coupler for optogenetics. Numerical Aperture (NA) Numerical Aperture (NA) defines the angle of the cone of light leaving the fiber tip at the end of the cannula. 0.22 NA fiber generates an intense cone of light over a smaller area. On the other hand, a 0.39 NA fiber generates a wide cone of light that illuminates a larger area with lower intensity (as seen in the diagram above). Optogenetics Product Family for In Vivo ApplicationsThe diagram below illustrates one application for the Y-bundles: bilateral stimulation. Thorlabs offers a wide variety of products designed to support in vivo optogenetics applications. Please visit the OG Selection Guide tab above to see a full listing of available products for different applications.
Laser-Induced Damage in Silica Optical FibersThe 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. ![]() Click to Enlarge Undamaged Fiber End ![]() Click to Enlarge Damaged Fiber End Damage at the Air / Glass InterfaceThere 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 FaceDamage 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 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 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) 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) 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![]() Click to Enlarge 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 MechanismsWhen 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 ThresholdIn 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 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 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 FibersGeneral Cleaning and Operation Guidelines
Tips for Using Fiber at Higher Optical Power
![]() Click to Enlarge Custom 1-to-4 Fan-Out Cable Custom Fiber BundlesThorlabs is pleased to offer custom straight and fan-out fiber bundles with random or mapped fiber configurations. The table below outlines some of our current bundle production capabilities. We are in the process of expanding these production capabilities, so do not hesitate to inquire if you do not see the bundle that you require described here. Some custom bundles will require techniques outside of our usual production processes. As a result, we cannot guarantee that we will be able to make a bundle configuration to fit the requirements of your specific application. However, our engineers will be happy to work with you to determine if Thorlabs can produce a fiber bundle that fulfills your needs. To receive a quote, please provide a drawing or draft of your bundle configuration. ![]() Click to Enlarge Custom Silica Fiber Bundle with SMA905 Connectors
Our cable engineers are available to help manufacture a bundle for your application.
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Posted Comments: | |
Mostafa Abdelhamid
 (posted 2019-09-07 14:12:59.003) Hi, I am doing an optogenetic experiment in the mouse brain and wanted to implement two cannulas (CFMLC12L02) and stimulate them simultaneously using fiber-coupled LED (M470F3), I am a bit confused between the use of either 1X2 fiberoptic couple (T200SL1A) or Bifurcated fiber bundle (BFYL2LS01).
I would be very happy if you would point out the main difference and optimal use of condition for each. Thanks a lot. YLohia
 (posted 2019-09-10 09:01:35.0) Hello, thank you for contacting Thorlabs. The main difference between a bundle and a coupler is that the bundle can be used bidirectionally, but is not intended to be used for equal power splitting applications. Power split done through fiber bundles have a strong dependence on the position and spatial profile of the input beam. user
 (posted 2019-05-13 12:15:31.933) Dear customer service representatives,
as a happy Thorlabs customer I regret to inform that I am disappointed with this product.
I would like to place a refund on my purchase of BFYL2LF01 . Unfortunately this product is not fit for use. The power splitting at the bifurcation is not equalized on any of the 4 fiber bundles I purchased, I have differences in transmission when comparing both output ferrule tips of almost 10-fold, making this product unsuited for my applications, which is bilateral optogenetic stimulation. For this I need a more balanced splitting for comparable light transmission. This product does not fulfill its purpose.
Two of the fibers were purchased with order number MS3383613 and are in its original state. These I would like to return for a full refund.
Two of the fibers I have made modifications at the tip and are not in the original state, but they never worked as intended nonetheless. Therefore, I would also like to request a refund for all the four fibers.
I appreciate the acknowledgement of this request.
Best regards,
Oscar Retana YLohia
 (posted 2019-05-13 04:31:19.0) Dear Oscar, thank you for your feedback. Please accept our apologies for any inconvenience caused by this product. I am reaching out to you via email to discuss your refund and to gather more details about your application to better understand where this issue could be arising from. |
Quick Links | |||
---|---|---|---|
Single-Site Stimulation | |||
One Light Source to One Cannula Implant | |||
Bilateral Stimulation | |||
One Light Source to Two Cannula Implants Using Rotary Joint Splitter | |||
One or Two Light Sources to Two Cannula Implants | |||
Two Light Sources into One Dual-Core Cannula Implant | |||
Illumination | |||
Fiber-Coupled LEDs and Drivers |
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.
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.
Click on Each Component for More Information
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.
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.
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
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
Part Selection Table (Click Links for Item Description Popup) | |||||||||
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Common Fiber Properties | |||||||||
Core Diameter | 200 µm | ||||||||
Wavelength Range | 400 - 2200 nm | ||||||||
NA | 0.39 | ||||||||
Fiber Type | FT200EMT | ||||||||
Ferrule Stylea | FC (Ø2.5 mm) | ||||||||
Dual-Core Patch Cable | FC/PC Input | BFY32FL1 | |||||||
SMA905 Input | BFY32SL1 | ||||||||
Compatible Mating Sleeve/Interconnect | ADAF1 ADAF2 ADAF4-5 |
||||||||
Dual-Core Fiber Optic Cannulaec | Stainless Steel | CFM32L10 CFM32L20 |
Popular Fiber-Coupled LEDs for Optogenetics | ||
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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 |
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.
Item # | Ferrule Size |
Common Connector |
Fiber Type |
Wavelength Range (Click for Plot) |
Core Diameter |
Cladding Diameter |
NA | Compatible Cannulae |
---|---|---|---|---|---|---|---|---|
BFYL1LS01 | Ø1.25 mm | SMA905 | FG200UCC | 250 -1200 nm | 200 ± 8 µm | 240 ± 5 µm | 0.22 | CFMLC22 Ceramic and CFML22 Stainless Steel |
BFYF1LS01 | Ø2.5 mm | CFMC22 Ceramic and CFM22 Stainless Steel |
Item # | Ferrule Size |
Common Connector |
Fiber Type |
Wavelength Range (Click for Plot) |
Core Diameter |
Cladding Diameter |
NA | Compatible Cannulae |
---|---|---|---|---|---|---|---|---|
BFYL1LF01 | Ø1.25 mm | FC/PC | FG200UCC | 250 -1200 nm | 200 µm ± 8 µm | 240 µm ± 5 µm | 0.22 | CFMLC22 Ceramic and CFML22 Stainless Steel |
BFYF1LF01 | Ø2.5 mm | CFMC22 Ceramic and CFM22 Stainless Steel |
Item # | Ferrule Size |
Common Connector |
Fiber Type |
Wavelength Range (Click for Plot) |
Core Diameter |
Cladding Diameter |
NA | Compatible Cannulae |
---|---|---|---|---|---|---|---|---|
BFYL2LS01 | Ø1.25 mm | SMA905 | FT200EMT | 400 - 2200 nm | 200 ± 5 µm | 225 ± 5 µm | 0.39 | CFMLC12 Ceramic and CFML12 Stainless Steel |
BFYF2LS01 | Ø2.5 mm | CFMC12 Ceramic and CFM12 Stainless Steel |
Item # | Ferrule Size |
Common Connector |
Fiber Type |
Wavelength Range (Click for Plot) |
Core Diameter |
Cladding Diameter |
NA | Compatible Cannulae |
---|---|---|---|---|---|---|---|---|
BFYL2LF01 | Ø1.25 mm | FC/PC | FT200EMT | 400 - 2200 nm | 200 µm ± 5 µm | 225 µm ± 5 µm | 0.39 | CFMLC12 Ceramic and CFML12 Stainless Steel |
BFYF2LF01 | Ø2.5 mm | CFMC12 Ceramic and CFM12 Stainless Steel |
Item # | Ferrule Size |
Common Connector |
Fiber Type |
Wavelength Range (Click for Plot) |
Core Diameter |
Cladding Diameter |
NA | Compatible Cannulae |
---|---|---|---|---|---|---|---|---|
BFYL4LS01 | Ø1.25 mm | SMA905 | FT400EMT | 400 - 2200 nm | 400 ± 8 μm | 425 ± 10 μm | 0.39 | CFMLC14 Ceramic and CFML14 Stainless Steel |
BFYF4LS01 | Ø2.5 mm | CFMLC14 Ceramic and CFML14 Stainless Steel |
Item # | Ferrule Size |
Common Connector |
Fiber Type |
Wavelength Range (Click for Plot) |
Core Diameter |
Cladding Diameter |
NA | Compatible Cannulae |
---|---|---|---|---|---|---|---|---|
BFYL4LF01 | Ø1.25 mm | FC/PC | FT400EMT | 400 - 2200 nm | 400 ± 8 μm | 425 ± 10 μm | 0.39 | CFMLC14 Ceramic and CFML14 Stainless Steel |
BFYF4LF01 | Ø2.5 mm | CFMLC14 Ceramic and CFML14 Stainless Steel |
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