Yb-Doped Polarization-Maintaining Double-Cladding Fiber Amplifiers

Optical fiber amplifiers and lasers are gaining widespread interest for high-power applications due to their numerous advantages over traditional solid-state and gas lasers including extremely high damage thresholds, excellent beam quality, superiorwavelength and temperature stability, small size, and very high powers using novel double-cladding fiber (DCF) geometry's. DCF devices are a unique solution for obtaining diffraction-limited high-power laser beams due to the ability to inject multiwattpump powers into their large-area and large-numerical aperature primary cladding. To date, however, polarization-maintaining DCF amplifiers have not been widely commercialized and may be critical to the future success of coherence-based power combinersfor kilowatt-class lasers and future optical fiber lidar instrumentation. During Phase I, Lambda Instruments investigated the feasibility of fabricating Yb-doped polarization-maintaining (PM) DCF as well as using conventional Yb-doped double-claddingfibers combined with novel fiber grating polarizers to obtain polarized, high-power light. During Phase II Lambda proposes to finalize the development of polarization-maintaining double-cladding fiber and demonstrate prototype amplifiers within aphase-locked laser array.