Asymmetric-waveguide gain-switched diode lasers: Design for optimal spectral properties for range finding and nonlinear applications

We report recent progress and discuss important issues in optimising the operating wavelength and spectral linewidth of gain-switched asymmetric waveguide lasers with a large effective spot size for applications ranging from optical radar systems to nonlinear optics. The active layer design for tailoring the emission wavelength to match the spectral sensitivity of the detectors for radar applications and its implications for the thermal management of the laser are discussed. Theoretical analysis and comparison of different schemes of spectral narrowing for nonlinear applications is presented, and the ways of maximising the performance improvement offered by the large effective spot size are discussed.