Temperature dependent photoreflectance on 2.3µm GaInAsSb-based vertical cavity surface emitting laser (VCSEL) structures were performed and show that the room temperature quantum well-cavity mode energy offset is 21meV; thermally-tuning into resonance at 220±2K.

Temperature-dependent photo-modulated reflectance (PR) spectroscopy has been applied to study a GaSb-based vertical-cavity surface-emitting laser (VCSEL) structure designed to operate at 2.3µm. To investigate the wavelength offset between the quantum well (QW) and cavity mode (CM) features, which determine the device's physical properties and temperature performance, the energies of the QW transitions relative to the VCSEL CM energy were tuned by heating from 9K to 300K. We found that this VCSEL structure has a QW-CM offset of 21meV at room temperature; also, the QW ground-state transition only comes into resonance with the CM at 220±2K. These PR results are closely compared with those obtained in a separate study of actual operating devices.