K. Takada

1.3-

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/mA1/2, respectively. The 40 Gb/s eye opened clearly at 25degC and eye-opening was observed up to 50degC.

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High relaxation oscillation frequency of 20.5 GHz and its slope of 3.2 GHz/mA1/2 were obtained by SI-BH 1.3-mum AlGaInAs MQW DFB lasers. Eye-opening up to 50degC was demonstrated as a result of 40-Gb/s direct modulation.

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

Low-drive-current 10-Gb/s operation at high temperatures was obtained for AlGaInAs buried-heterostructure λ/4-shifted DFB lasers. At 100 °C, f<inf>r</inf> at I<inf>th</inf> + 50 mA was 10.8 GHz and 10-Gb/s modulation was achieved at I<inf>mod</inf> = 22 mA<inf>p-p</inf>.

40-Gb/s direct modulation of 1.3-μm semi-insulating buried-heterostructure AlGaInAs MQW DFB lasers

1.55-mum-wavelength AlGaInAs semi-insulating buried-heterostructure (SI-BH) lasers were investigated. AlGaInAs lambda/4-phase-shift DFB SI-BH lasers with good high temperature characteristics as well as stable single-mode oscillation were fabricated for the first time

Low-Drive-Current 10-Gb/s Operation of AlGaInAs Buried-Heterostructure λ/4-Shifted DFB Lasers

We introduce our recent works on directly-modulated AlGaInAs quantum-well lasers with semi-insulating buried-heterostructure for ultra-high-speed transmission. The short-cavity 1.3-µm-wavelength DFB lasers showed low-penalty transmission up to 13 km under direct modulation at 25 Gbps, as well as clearly-opened eye patterns by 40-Gbps direct modulation. For further reduction of driving current in the high-speed directly-modulated lasers, we developed the distributed reflector lasers with the active-region having the length of 100 µm or less, sandwiched by the passive reflectors. The fabricated distributed reflector lasers exhibited very high slope value of relaxation oscillation frequency of 4.0 GHz/mA½ and more. The distributed reflector lasers emitting in 1.3-µm wavelength region achieved 40-Gbps direct modulation with the driving current of 2/3 of that by the DFB lasers. By the distributed reflector lasers of 1.55-µm-wavelength, high temperature 40-Gbps operation was realized as well as reduction of driving current.