Longitudinal mode control in long cavity VCSELs with a curved mirror

Abstract

A single cavity filtering mirror with a highly varying reflectivity spectrum was used to demonstrate a single longitudinal mode operation for a VCSEL with a ∼25 μm cavity length. The 443.5 nm lasing peak had an SMSR of 42 dB at 9 mA, 70 kA cm-2. Increasing the number of DBR pairs between the VCSEL and filtering mirror cavity reduced the simulated optical standing wave in the mirror cavity by 57% and experimentally gave a 42% increase in the slope efficiency to achieve 2.56 mW at 7 mA from a device with a 4 μm aperture with a single longitudinal mode.