1.3- $\mu$ m AlGaInAs Multiple-Quantum-Well Semi-insulating Buried-Heterostructure Distributed-Feedback Lasers for High-Speed Direct Modulation

This paper describes 1.3-mum AlGaInAs multiple-quantum-well semi-insulating buried-heterostructure distributed-feedback lasers for high-speed direct modulation. Combination of large differential gain AlGaInAs quantum wells and semi-insulating buried-heterostructure for reduction of active region achieved 25 and 40 Gb/s direct modulation with the device having the cavity length of 150 mum. The device whose Bragg wavelength is longer than gain peak wavelength showed 25 Gb/s direct modulation characteristics with superior temperature characteristics. The relaxation oscillation frequency of this device was 15 GHz and higher up to 70degC. Clear eye-opening was observed and single-mode fiber transmission experiments showed low power penalty up to 70degC. With the device of negative detuning with larger differential gain, we achieved 40 Gb/s direct modulation. This device showed high relaxation oscillation frequency and slope of 20.5 GHz and 3.2 GHz/mA^1/2, respectively. The 40 Gb/s eye opened clearly at 25degC and eye-opening was observed up to 50degC.