Improved linearity and kink criteria for 1.3-μm InGaAsP-InP channeled substrate buried heterostructure lasers

Nonlinearities or kinks in the light-current characteristics of channeled substrate buried heterostructure lasers are associated with higher order transverse mode transition and lateral mode movement. The active area has been reduced to stabilize the transverse mode. Fundamental mode operation up to high powers (24 mW/facet) has been obtained in devices with threshold current as low as 15 mA. Measurements and calculations are presented which show that nonlinearities occur at higher output power in lasers with reduced active area.