3.5-W, 42-MHz, single-mode chirped pulse amplification fiber laser system at 1560 nm

Abstract

There is much interest in the development of high power ultra-short fiber laser systems due to their significant properties and applications. Among them, Er-doped fiber lasers are showing more attention, especially in silicon processing and photovoltaic industries. Chirp pulse amplification (CPA) is the most common approach to establish high-power/high energy fiber lasers. Here, we demonstrate a CPA fiber laser system operating at 1560 nm. The system provides 3.5 W average output power at 42 MHZ pulse repetition rate corresponds to 83 nJ pulse energy. The laser system comprises a passively mode-locked oscillator and two amplifier stages, where the power amplifier is based on claddingpumped 10 μm-core EY co-doped fiber. The output pulses are compressible to 180 fs by using of two compressor gratings. The schematic of experimental setup is shown in Fig. 1(a). Seed source is a home-built dispersion-managed passively mode-locked oscillator delivering 5-ps long pulses at 42 MHZ repletion rate and 8 mW average power. We are using 70-cm long positive dispersion fiber (OFS, R2=56.7 fs2 /mm) after the gain fiber to manage group velocity dispersion delay (GDD) of the cavity and achieve broad spectrum. The output from oscillator delivers to stretch fiber including a 10-m long fiber (OFS). 30-ps long pulses after that delivers to the first stage amplifier, which consists of 1-m long Er 80-4/125 (CorActive) pumped by a single-mode diode laser at 976 nm via a wavelength-division-multiplexer (WDM). The first stage amplifier generates 120 mW of average power. The power amplifier is based on 1.4-m long Er-Yb co-doped fiber with 10 μm core and 128 μm cladding diameter. The pump source is a 16-W wavelength-stabilized diode laser at 976 nm. The pump and signal are combined with a multimode pump signal combiner (MPC). A 10/128 fiber pigtailed collimator is used to collimate output beam.