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3-Wavelength, Single Mode WDMs![]()
RGB50HF 488, 561, and 640 nm WDM with FC/PC Connectors RGB50HA 488, 561, and 640 nm WDMwith FC/APC Connectors Application Idea RGB46HA WDM (FC/APC Connectors) Mounted on Thorlabs' FCQB Mounting Base Related Items ![]() Please Wait
![]() Click for Details The ports on the 3-Wavelength WDM are labeled with the wavelength. The common port (COM) has a white jacket. Features
Thorlabs' 3-Wavelength Wavelength Division Multiplexers (WDMs), also known as RGB Combiners, allow light of three different wavelengths to be combined into a single output fiber. Seven wavelength combinations are available; options are listed in the table to the right. They can also be used in reverse, splitting three wavelengths entering the common port into three separate output ports. As seen in the image to the above right, a label on the top of the housing indicates the wavelength for each port, or channel. Additionally, the jacket on each fiber leg is color coded (visible wavelengths only); white indicates the common port. Each of the ports with an assigned wavelength has a ±5 nm bandwidth around that center wavelength. The graphs provided below give an example of the insertion loss in each channel for each of the color combinations offered. An insertion loss close to zero indicates high transmission at that wavelength, while a high value of insertion loss indicates low transmission of the signal. These WDMs provide low crosstalk (good isolation) between the wavelengths in each port; for each channel, signals at the center wavelengths of the other two channels are suppressed by at least 10 dB relative to the channel's specified wavelength. The 3-wavelength WDMs are tested during the manufacturing process to ensure that they meet specifications. Each RGB combiner is shipped with a detailed test report that includes transmission and isolation measurements as well an insertion loss plot showing the performance of Ports 1, 2, and 3. Please see below for sample data sheets for each wavelength combination. Our WDMs have undergone extensive testing to ensure they meet or surpass Telcordia requirements; please see the Reliability Testing tab for details. Each WDM is contained in a compact 3.94" x 3.15" x 0.39" (100.0 mm x 80.0 mm x 10.0 mm) housing that includes four through holes for mounting the device to our FCQB mounting base (available separately below). All fiber leads are jacketed in Ø900 µm loose Hytrel® tubes and are 0.8 m long. These WDMs are offered from stock with 2.0 mm narrow key FC/PC or FC/APC connectors. Additionally, Thorlabs offers 2-wavelength combiners (for visible wavelengths), single mode WDMs (for NIR and telecom wavelengths), and polarization-maintaining WDMs. Other fiber types, connectors, and select wavelength combinations are available upon request. Please contact Tech Support with inquiries.
RGB Combiner DesignThorlabs' RGB Combiners are designed to combine light at three wavelengths into a single common fiber. As shown in the diagram below, the combiner internally consists of two fused fiber wavelength combiners that merge light from the three wavelength ports (ports 1 - 3) into a single output (common port). In the combiner shown in the diagram below, light from port 1 and port 3 are combined first, and then light from port 2 is added using a second wavelength combiner. Depending on the wavelength configuration of each port, the order in which the ports are combined may vary. Because RGB combiners are bidirectional, the they can also split light inserted into the common port. For optimal splitting performance, the input light should only contain wavelengths specified for the three output ports. Out-of-band performance can be estimated using the data sheets provided with each RGB combiner; click here for a sample data sheet or see below for sample data sheets for each wavelength combination. Schematic of the internal components of an example RGB Combiner. The zoom panel shows an example configuration of how (ports 1 - 3) are combined into the common port. ![]() Click to Enlarge The shaded regions in the plot indicate the bandwidth where each port meets the specified performance. RGB Combiner Manufacturing and Verification ProcessTo manufacture the RGB combiner, three optical fibers are fused together to form the two wavelength couplers that comprise the RGB combiner. This section details the step-by-step process for manufacturing and verifying the performance of an example RGB combiner. The exact configuration of the fibers within the combiner may vary depending on the specified wavelengths. During each manufacturing step, the output power and insertion loss (IL) at each port is monitored. As seen in the graph to the right and definition below, insertion loss (measured in dB) is the ratio of the input power to the output power from each leg of the coupler as a function of wavelength. Each port of the coupler is designed to have high transmission of a single wavelength while supressing other wavelengths, which minimizes cross talk between the ports. where Pin and Pout are the input and output powers (in mW). ![]() Click to Enlarge In the diagram, the fibers are color-coded; green for port 2 (middle wavelength) and violet for a mix of short and long wavelengths. Step 1At the first stage, two fibers are fused on a manufacturing station to separate out the center wavelength channel of the RGB combiner. The output in this channel is monitored during the fusing process using a source on one side and an optical spectrum analyzer (OSA) on the other. The insertion loss as a function of wavelength is calculated from the spectrum obtained from the OSA. ![]() Click to Enlarge In the diagram, the fibers are color-coded; green for port 2 (middle wavelength) and violet for a mix of short and long wavelengths. Step 2The other fiber end from the first wavelength split contains both the short and long wavelengths of the original source. The insertion loss from the short/long wavelength channel can be similarly determined using a source and OSA at this port. ![]() Click to Enlarge In the diagram, the fibers are color-coded; green for port 2 (middle wavelength), violet for a mix of short and long wavelengths, blue for port 1 (short wavelength), and red for port 3 (long wavelength). Step 3To separate the short and long wavelength channels after the first split, a second fused fiber stage is added (shown in the diagram to the right). The output from the short wavelength channel is measured during the fusing process and the insertion loss is calculated from these measurements. ![]() Click to Enlarge In the diagram, the fibers are color-coded; green for port 2 (middle wavelength), violet for a mix of short and long wavelengths, blue for port 1 (short wavelength), and red for port 3 (long wavelength). Step 4In the final step, the output from the long wavelength port is measured using the OSA for quality control. At this point, unused fiber leads at each wavelength split are terminated. The insertion loss from each output port can be combined to generate the insertion loss plot shown above.
GR-1221-CORE TestingOur Single Mode Wavelength Division Multiplexers (WDMs) have undergone extensive testing to ensure they meet or surpass Telcordia requirements outlined in the regulation titled Generic Reliability Assurance Requirements for Passive Optical Components, Issue 2 (GR-1221-CORE). The results of this testing program qualify the WDMs and their manufacturing process for volume production. The selected test conditions are for uncontrolled environments and are considered to be some of the most stringent test conditions for passive components. To download a PDF of this test report, please click here. ![]() Close-Up of Mechanical Shock Test Setup ![]() SM-105 Mechanical Shock Test Machine ![]() Click To Enlarge Vibration Test Setup ![]() Damp Heat Testing Setup Testing ConditionsThis test program consisted of five test groups with a sample size of 11 per group. Testing was conducted with a 1310 nm laser source input into 980/1310 WDMs using a 1x16 waveguide coupler. The two outputs of every WDM were measured by a PM100USB power meter with an S154C sensor head.
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 Click Here for Raw Data This plot shows an example of the spectral performance of a RGB26 3-wavelength WDM. The lines represent the spectral response of each channel, while the colored regions denote the bandwidth around the center wavelengths. This data is typical; performance of each WDM may vary from unit to tunit. Data was obtained without connectors.
![]() Each WDM is shipped with a detailed test report that includes transmission and isolation measurements as well an insertion loss plot showing the performance of Ports 1, 2, and 3. ![]() ![]() Click to Enlarge Click Here for Raw Data This plot shows an example of the spectral performance of a RGB30 3-wavelength WDM. The lines represent the spectral response of each channel, while the colored regions denote the bandwidth around the center wavelengths. This data is typical; performance of each WDM may vary from unit to tunit. Data was obtained without connectors.
![]() Each WDM is shipped with a detailed test report that includes transmission and isolation measurements as well an insertion loss plot showing the performance of Ports 1, 2, and 3. ![]() ![]() Click to Enlarge Click Here for Raw Data This plot shows an example of the spectral performance of a RGB46 3-wavelength WDM. The lines represent the spectral response of each channel, while the colored regions denote the bandwidth around the center wavelengths. This data is typical; performance of each WDM may vary from unit to tunit. Data was obtained without connectors.
![]() Each WDM is shipped with a detailed test report that includes transmission and isolation measurements as well an insertion loss plot showing the performance of Ports 1, 2, and 3. ![]() ![]() Click to Enlarge Click Here for Raw Data This plot shows an example of the spectral performance of a RGB50 3-wavelength WDM. The lines represent the spectral response of each channel, while the colored regions denote the bandwidth around the center wavelengths. This data is typical; performance of each WDM may vary from unit to tunit. Data was obtained without connectors.
![]() Each WDM is shipped with a detailed test report that includes transmission and isolation measurements as well an insertion loss plot showing the performance of Ports 1, 2, and 3. ![]() ![]() Click to Enlarge Click Here for Raw Data This plot shows an example of the spectral performance of a RYB54 3-wavelength WDM. The lines represent the spectral response of each channel, while the colored regions denote the bandwidth around the center wavelengths. This data is typical; performance of each WDM may vary from unit to tunit. Data was obtained without connectors.
![]() Each WDM is shipped with a detailed test report that includes transmission and isolation measurements as well an insertion loss plot showing the performance of Ports 1, 2, and 3. ![]() ![]() Click to Enlarge Click Here for Raw Data This plot shows an example of the spectral performance of a ROB58 3-wavelength WDM. The lines represent the spectral response of each channel, while the colored regions denote the bandwidth around the center wavelengths. This data is typical; performance of each WDM may vary from unit to tunit. Data was obtained without connectors.
![]() Each WDM is shipped with a detailed test report that includes transmission and isolation measurements as well an insertion loss plot showing the performance of Ports 1, 2, and 3. ![]() ![]() Click to Enlarge Click Here for Raw Data This plot shows an example of the spectral performance of a RNN50 3-wavelength WDM. The lines represent the spectral response of each channel, while the colored regions denote the bandwidth around the center wavelengths. This data is typical; performance of each WDM may vary from unit to tunit. Data was obtained without connectors.
![]() Each WDM is shipped with a detailed test report that includes transmission and isolation measurements as well an insertion loss plot showing the performance of Ports 1, 2, and 3. ![]()
Our FCQB mounting base provides two 2.25" (57.2 mm) long clearance slots for 1/4" (M6) cap screws for mounting Thorlabs' RGB wavelength combiners or 1x4 couplers to an optical table or other tapped surface. The two clearance slots are located 4" (101.6 mm) apart at opposite edges of the mounting base. Four M2 taps between the clearance slots are positioned to align with the through holes in Thorlabs' RGB wavelength combiners and 1x4 SM couplers. Four M2 screws are included. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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