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Development of high power wavelength division multiplexers

Description:

OBJECTIVE: To advance the power handling capability of Wavelength Division Multiplexers (WDM) in both PM and non-PM fiber. DESCRIPTION: Separate fibers into the core of a single fiber. The WDM works by first collimating the light from each fiber. The collimated beams, which are combined using a dichroic filter, are then focused into the output fiber. The WDM can also be run in reverse and used to separate two wavelengths of light from a single fiber into two separate fibers. Most development of WDMs has been done to support the lower power telecommunications industry. Such WDMs use traditional step index silica based fiber and typically have at most, a power handling capacity of 10 W. This is a major limiting factor for numerous high power laser applications to include two tone seeded lasers, seeded Raman lasers for high power operation, etc. There is a need to develop WDMs of increased power handling capacity of up to 150 W in traditional step index fiber at the wavelengths required for the various high power applications. WDM manufacturing technology needs to support the common fiber sizes to include 6/125, 10/125, and 20/400 fiber as well as polarization maintaining and non-polarization maintaining fiber. Besides traditional step-index fiber, there is also a need to develop high power WDMs in photonic crystal fiber (PCF) to support high power applications. PCF, which is uniform along its length, has a cross-section consisting of one or more materials in the form of hexagonal rods arranged periodically over the cross-section. Surrounding the core is a cladding which consists of a hexagonal lattice of air holes. This material is vastly different from traditional step-index fiber. WDMs in this material will involve fibers having a larger core than those found in traditional step-index fiber. In addition, WDM technology in photonic crystal fiber needs to have a power handling capability of 200 W and needs to support both polarization maintaining and non-polarization maintaining fiber. PHASE I: 1. Feasibility of various manufacturing techniques to produce WDMs in PM and non- PM step index fiber such that the power rating is 10 W for 6/125 fiber, 100 W for 10/125 fiber and 200 W for 20/400 fiber. 2. Feasibility of various manufacturing techniques to produce WDMs in PM and non- PM photonic crystal fiber such that the power rating is 150 W for a seven rod core. PHASE II: 1. Develop a technique to manufacture WDMs having high power ratings in both PM and non-PM traditional step index fiber. Deliver five PM WDMs capable of combining 1121 and 1178 nm in 10/125 fiber with a power rating of 100 W and five PM WDMs capable of combining 1069 and 1178 nm in 20/400 fiber such that the power rating is 200 W. 2. Develop technique to manufacture WDMs in PM and non-PM PCF. PHASE III: Continue development of WDMs in step index and PCF in order to meet the delivery specifications. REFERENCES: 1. Photonic crystal fiber: Russell, et. al., Journal of Lightwave Technology 24(12)(2006)4729. 2. WDMs in PCF: Liu, et. al., Optics Letters 36(14)(2011)591. 3. WDMs in general: http://en.wikipedia.org/wiki/Wavelength-division_multiplexing 4. Classic paper on a WDM: Digonnet, et. al., IEEE Journal of Quantum Electronics 18(1982)746.
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