Transverse mode competition in narrow-ridge diode lasers
The influence of waveguide parameters (thicknesses and contrasts in both transverse and
lateral directions) on optical mode compositions in narrow-ridge lasers is numerically
investigated. The proposed numerical model explains our experimental results on the drastic
difference in optical mode compositions in broad-area and narrow-ridge lasers processed from
the same wafer based on a broadened GaAs/AlGaAs transverse-waveguide heterostructure.
It is shown that in the broadened transverse waveguides the fundamental mode tends to
have a much lower 2D optical confinement factor than high-order modes. We suppose
that waveguides possessing no more than two transverse eigenmodes would provide more
opportunities for designing narrow-ridge lasers with robust single-mode emission.