High-speed (20 Gb/s), low-drive voltage (2 Vp-p) strained InGaAsP mqw modulator/DFB laser light source

This paper describes a monolithically integrated light source module of a high-speed/low-driving voltage multiquantum well (MQW) optical modulator and DFB laser for 1.55-μm applications. This paper investigates: (1) device structure suitable for growing high-quality crystal, (2) efficient performance due to adoption of a strained InGaAsP MQW, (3) reduction of device capacitance using polyimide at the electrodes of the optical modulator, and (4) realization of a monolithically integrated module using lens coupling. In the test device, the oscillation threshold current was below 15 mA, the extinction ratio was over 20 dB when the bias voltage was −2 V, the frequency band was 15 GHz (−3 dB), and the optical power coupled to an optical fiber was 2.5 mW. Optical modulation at 15 Gb/s was carried out at a driving voltage of 1 Vp-p. When this device was used under 2 Gb/s high-speed modulation using a driving voltage of 2 Vp-p for 100-km transmission, the minimum optical power sensitivity was −23 dBm and the power penalty was 1 dB. This result indicates that this monolithically integrated optical source is suitable for large-capacity/long-distance optical communication.