Supercontinuum (SC) light sources have attracted attention as broadband light sources for applications such as measuring the wavelength characteristics of optical components and optical coherence tomography. Our laboratory has achieved SC generation with a highly flat spectrum and excellent long-term stability by utilizing a Noise-like pulse (NLP) source. In measurements, improving the signal-to-noise ratio and the measuring throughput require high-power SC.

　This study developed an all-fiber coherent beam combining (CBC) system with passive phase and polarization matching, using polarization-stabilizing erbium-doped fiber amplifier (PS-EDFA) to amplify NLP. CBC is a method of amplification that integrates multiple fiber outputs into a single light beam by utilizing the coherence of the laser. The conventional method of CBC requires the control of both phase and polarization. In our new system, one pulse is split into two pulses. Then the pulses are amplified by a single PS-EDFA. The PS-EDFA was constructed by combining an erbium-doped fiber amplifier (EDFA), a polarization beam splitter (PBS), and a Faraday rotator mirror (FRM). The input and output ports of the PBS in the PS-EDFA exchange roles because the FRM rotates the polarization state of the reflected light by 90°. In addition, the FRM compensates for changes in the polarization state. Thus, the PS-EDFA automatically matches phase and polarization, enabling CBC for NLP with a short coherence length. The maximum and minimum output powers of the CBC for NLP were 252.0 mW and 251.1 mW, respectively, for 1 hour. Therefore, the combining efficiency is 98.7% with a fluctuation of 0.9%.