3 mJ All-Fiber MOPA With a Short-Length Highly Er3+-Doped Phosphate Fiber

Abstract
A very large mode-area 2 wt% erbium-doped double-clad phosphate fiber with a core diameter of 60 μm and core numerical aperture of 0.03 was fabricated and used for the last stage amplifier of an all-fiber pulsed laser master-oscillator power amplifier (MOPA) at 1550 nm. The Er3+ double-clad phosphate fiber has a cladding-core ratio of 2.17 and a V number of 3.6 at 1550 nm. 3 mJ pulses with 21.5 ns duration were obtained with Gaussian-like spatial beam profile with only a 75 cm long phosphate gain fiber.
Funding Information
  • Army SBIR Phase II (W9113M-19-C-0065)
  • Technology Research Initiative Fund (TRIF) Photonics Initiative of the University of Arizona