Half-Ring Microlasers Based on InGaAs Quantum Well-Dots with High Material Gain

We report on half-ring lasers that are 100-200 mu m in diameter and are fabricated by cleaving the initial full rings into halves. Characteristics of the half-ring and half-disk lasers fabricated from the same wafer are compared. The active area of the microlasers is based on the quantum heterostructures of mixed (0D/2D) dimensionality, referred to as quantum well-dots with very high material gain. Half-ring lasers show directional light emission and single-mode lasing near the threshold. A maximal continuous-wave output power of 76 mW is achieved for a half-ring that is 200 mu m in diameter. Half-rings demonstrate better wall-plug efficiency as compared to half-disks. Lasing in pulse mode is observed up to 140 degrees C, the characteristic temperature is 100-125 K, depending on the half-ring size. P-side down bonding onto Si-board significantly improves power and temperature characteristics. In CW mode, lasing is maintained up to 97 degrees C, limited by active-area overheating.