High-speed short cavity strained-layer multiple quantum well lasers

The high-speed response and optical properties of strained-layer In_0.3Ga_0.7As four and five quantum-well ridge waveguide lasers fabricated by chemically-assisted ion beam etching (CAIBE) are presented. The threshold current variation with cavity length is very similar for the two-layer designs, but the differential gain decreases more quickly with optical loss in the four quantum-well devices. Consequently, whereas the 200-400 μm cavity length lasers from the four quantum-well wafer are superior to those from the five quantum-well layer in terms of high speed performance, the 50- and 100-μm long devices are nearly identical. A CW 3-dB bandwidth of 22 GHz and a record 3-dB bandwidth of 26 GHz under pulsed bias have been measured on 50μm long lasers. 100-μm cavity length lasers exhibit excellent modulation efficiency with a typical 3-dB bandwidth of 20 GHz