Characterisation and comparison between different S-bend shaped GaAs Y-branch distributed Bragg reflector lasers emitting at 976 nm

Abstract

Passive S-bend waveguides have been thoroughly studied in the past, however active S-bend structures such as those in Y-branch distributed Bragg reflector (DBR) ridge waveguide (RW) lasers have been paid little attention. In this work, different S-bend based Y-branch DBR lasers emitting at 976 nm are developed, and their electro-optical, spectral and spatial characteristics are characterised. In total, two types of active S-bend (sinusoidal, cosinusoidal) as well as single-bend cosinusoidal Y-branch DBR-RW laser structures are investigated and their performances are compared to a reference straight DBR-RW laser. It is shown that among the investigated devices, the Cos S-bend based Y-branch laser provides the highest single-mode output power. However, when considering the spatial characteristics, the experimental results suggest that the Sin S-bend based Y-branch laser offers the best beam quality, and should be used in applications where good spatial characteristics are important. Finally, the experimental beam parameters are compared to passive waveguide simulations.