Spatial filtering of a six-wavelength DBR-RW laser in a MOPA system.

Abstract

Lasing emission at multiple wavelengths can be used in different sensing applications and in optical telecommunication. In this work, we report a six-wavelength distributed Bragg reflector (DBR) laser, emitting around 976 nm with six ridge waveguide (RW) structures, where individual DBR gratings are combined into a common front section. These six elements are individually addressable and biased one at a time for individual wavelength selection. The drawback of this RW combination is observable in spatial characteristics where higher-order modes are supported. We addressed this issue by using a master oscillator power amplifier (MOPA) system that combines the six-wavelength MO laser with a tapered PA. Through this configuration, the PA acts as a spatial filter of the MO beam, providing a nearly diffraction-limited beam with M1/e22<1.5. In addition, the described MOPA system provides output powers around 4 W with spectral single-mode operation, with up to 9.36 nm of thermal wavelength tuning. We believe that the described MOPA configuration can be used in different applications, such as absorption spectroscopy.