1550 nm external cavity diode laser with enhanced SMSR based on polarization mismatch by grating rotation

摘要

A tunable external cavity diode laser (ECDL) with high side-mode suppression ratio (SMSR) is demonstrated. The ECDL is operated at both strong and weak feedback steady states with single longitudinal mode. Compared with the strong feedback mode, the SMSR of the weak feedback mode is significantly enhanced by rotating the grating along the axis of the incident beam, which changes the polarization orientation versus the grating grooves. The highest SMSR of the weak feedback mode is 54 dB at the injection current of 300 mA. The tunable range of the ECDL with weak feedback mode reaches 130.9 nm. (C) 2019 Optical Society of America