Characterization and comparison between two coupling concepts of four-wavelength monolithic DBR ridge waveguide diode laser at 970 nm

Abstract

Compact laser sources emitting at multiple wavelengths from a single aperture are interesting in a multiple of applications. In this work, we characterize and compare two concepts of four-arm monolithic distributed Bragg reflector (DBR) ridge waveguide (RW) diode lasers emitting at four different wavelengths around 970 nm. The first concept has a single intersection point, where the four arms are joined before being emitted from the output aperture. The second concept has two intersection points: the first where the inner two arms are combined and a second where those are joined by the outer two arms. In the first case, the inner and outer arms show difference in performance, in particular the outer arms show worse opto-electrical and spatial parameters compared to the inner arms. In the second concept, similar performance is observed from all four arms, with smaller deviations between the inner and outer arms in the mentioned parameters. This study suggests that a serial combination of pairs of bends is preferable in this kind of multi-wavelength laser sources.