GaAs-AlxGa1-xAs injection lasers with distributed Bragg reflectors

Room-temperature operation of an optically integrated double heterostructure (DH) GaAs-AlxGa1-xAs injection laser with a distributed Bragg reflector (DBR), with threshold current densities of 5 kA/cm2 is reported. The DBR was in the form of a third-order grating which was ion milled on a passive single heterostructure (SH) waveguide section with the latter taper coupled to the active DH section. The observed half-power spectral bandwidth was ≲1 Å. A highly collimated beam output with a half-power divergence angle of ≲0.3° was also achieved by coupling the scattered light from the oil-immersed grating at the Bragg angle with a prism.