A Self-Injection Locking MOPA Laser for High Power External Cavity Enhancing Optics

Abstract

External cavity enhancing nonlinearity provides a powerful architecture for new lasing spectrum generations. However, its realizations are traditionally sophisticated with locking circuits required, limiting its wide applications. In this letter, we break this limit by devising the first optical locking MOPA laser, with seed source of a MOPA fiber laser self-injection locking to a high-quality (Q) nonlinear fiber resonator (NFR). The self-injection locking MOPA laser reaches a spectral linewidth of 3.9kHz at its maximum output power of 4.78W, which is $\sim 5.5\times 10 ^{\mathbf {2}}$ linewidth reduced from the free running state. An up to 50-nm bandwidth of four wave mixing (FWM) spectrum is generated from the NFR, at 4.78-W output power of the self-injection locking MOPA laser. Such locking regime is environmentally stable, owing to the frequency pulling effect of the locked seed source to the NFR. This work paves an all optical locking scheme for high power external cavity enhancing optical systems, which will benefits nonlinear spectrum generations in a more simple, high efficiency and high linewidth performance way.