High-Speed Direct-Modulated Unidirectional Emission Square Microlasers

High-speed modulation characteristics are investigated for a 20-μm-side-length AlGaInAs/InP square resonator microlaser with a 1.5-μm-wide midpoint output waveguide. Single-mode operation with a maximum output power of 0.34 mW and a side mode suppression ration of 42 dB are realized for the microlaser at a temperature of 288 K. A 3-dB bandwidth of 14.9 GHz is obtained, and the eye diagrams at 15 and 20 Gb/s are demonstrated for the microlaser with a bias current of 30 mA. Furthermore, the bit error rate of 2 × 10−8 is obtained at 8 Gb/s for a square microlaser with a 3-dB bandwidth of 10 GHz. In addition, different output patterns are observed for different lasing modes, which agree with the finite-difference time-domain simulation results.