Lateral mode control in stripe contact injection lasers

Injection lasers having nonlinearities or "kinks" in their P-I (power-current) curves are due primarily to lateral mode hopping and waveguide shifting with current. This paper is aimed at the fabrication of linear devices with due considerations of waveguide design for lateral mode stability. We model a heterostructure laser and calculate a lateral dielectric discontinuity based on the gain/loss profile of the active layer and the overall geometry. This discontinuity serves as a figure of merit for lateral mode stability. We compare two important double-heterostructure lasers: (1) the oxide-stripe geometry, and (2) the channeled substrate planar (CSP). Calculations show that CSP devices have strong lateral index confinement, whereas, the oxide-stripe lasers have a lateral gain confinement dependent upon drive.