Diode-pumped solid-state laser pumping of co-doped erbium optical amplifiers

Abstract

The majority of recent work on erbium-doped fiber amplifiers has been centered on the choice of the pumping source, especially with regards to scalability in ultrahigh output erbium power amplifiers. There have been high-output power erbium amplifiers demonstrated using multiple pump diodes both at 980 and 1480 nm.1 However, there are serious questions regarding power scalability when more than two pump diodes are required. We have chosen to pump on the long-wavelength tail of the Yb+3 absorption at 1064 nm in Er/Yb co-doped fibers using a diode-pumped Nd:YAG laser (DPL). The advantages of using a DPL are the use of mature, efficient, and high-power AlGaAs diode laser arrays, the high output beam quality, and power scaling advantage. We utilize the DPL as a brightness convener and have been able to couple >300 mW from a single DPL into single-mode fiber. Unlike direct diode excitation, this approach is nearly arbitrarily scalable in power with increasing nondiffraction-limited pump array or bar size.