Design and numerical study of a built-in channel waveguide laser with experimental verification of fundamental-mode dominant operation

Abstract We proposed and fabricated a novel built-in channel waveguide (BCW) laser for 1.3 μm AlGaInAs/InP that enables fundamental lateral-mode at wider stripe widths. The BCW laser integrates a p-GaInAsP channel waveguide in the upper p-InP cladding and a p-InP spacer above the active region to tailor the vertical and lateral effective index profiles. Two-dimensional eigenmode simulations predict a single-mode cutoff channel width of approximately 6.2 μm for a 0.10 μm thick channel and a 0.20 μm thick spacer. The simulation using the self-consistent Travelling Wave Laser Model demonstrates that the 6 μm BCW can deliver a light output power over 500 mW for 1 mm long device with high reflectivity/low-reflectivity coatings. First-trial 1 mm long BCW lasers exhibited single-lobed lateral far fields with a channel width of 6.5 μm devices. These findings confirm an extended operating window for AlGaInAs/InP BCW lasers, enabling compact, high-power transmitters with good beam quality.