The impact of thermal effects on the performance of vertical-cavity surface-emitting lasers based on sub-monolayer InGaAs quantum dots

Abstract

The laser characteristics of 0.98 µm vertical-cavity surface-emitting lasers based on sub-monolayer InGaAs quantum dots (QDs) were studied in a broad temperature range. Devices demonstrated low internal optical losses, high differential efficiency and relatively small resistances due to the QD active region together with an optimal design of doped distributed Bragg reflectors. It is found that the temperature dependence of threshold current and differential efficiency depends not only on the temperature sensitivity of the active region, but also on the lineshape of the gain curve and spectral misalignment between the gain maximum and cavity mode. A simple method of estimation of gain-cavity detuning has been proposed.

Removing Thermal Gain–Cavity Detuning Effect Based on Supergain Quantum Well–Wire Hybrid Nanostructures for Single-Frequency Laser Diodes

“…It leads to a thermal mismatch between both so that the effective gain available by the cavity mode is sharply reduced when the device temperature is changed. As a result, the threshold carrier density of the device rises and the conversion efficiency drops, accordingly. − Therefore, the performance of a single-frequency laser diode is associated with not only thermal carrier-leakage loss over barriers of the quantum structure but also the extra thermal gain–cavity detuning effect. This problem does not exist for other types of laser diodes.…”

Dynamic Characteristics and Linewidth Enhancement Factor of Quantum-Dot Vertical-Cavity Surface-Emitting Lasers

“…The resonance frequency is approximated proportional to the square root of the injected current relative to threshold before saturation takes place. The previous investigation [15] revealed the lasing emissions of QD VCSELs via the ground-state transition at low temperature, while via the excited state transition at room temperature. At the lowest ambient temperature of −45…”