Kazumasa Takabayashi

Experimental demonstration of 448-Gbps+ DMT transmission over 30-km SMF

We have experimentally demonstrated 469-Gbps transmission over 30-km SMF using DMT on a LAN-WDM system for 400-Gbps Ethernet. Only four directly modulated lasers and direct detectors as optical devices were necessary to achieve the results.

10 Gb/s Wavelength-Tunable EML with Continuous Wavelength Tuning Covering 50 GHz × 8 Channels on ITU Grid

A wavelength-tunable EA-modulated laser (wavelength-tunable EML) using tunable distributed amplification (TDA) structure was demonstrated. An 80 km transmission of 10 Gb/s signals was confirmed on 8 channels on ITU grid using the devices simple, continuous tuning mechanism.

Mode-Hop-Free and Electrically Wavelength-Tunable Laser Array with 39.5 nm Tuning Range using Tunable Distributed Amplification DFB Structure

An electrically wavelength-tunable laser array with tunable distributed amplification (TDA) DFB structure has been developed for the first time. A tuning range of 39.5 nm has been achieved by monolithic array of 8-channel mode-hop-free lasers

1.3-μm-Wavelength AlGaInAs Multiple-Quantum-Well Semi-Insulating Buried-Heterostructure Distributed-Reflector Laser Arrays on Semi-Insulating InP Substrate

1.3-μm-wavelength AlGaInAs distributed-reflector laser arrays on semi-insulating InP substrate for high-speed direct modulation are investigated to realize compact and low-power-consumptive optical modules. Combination of AlGaInAs quantum wells with large differential gain and semi-insulating buried-heterostructure for reduction of the volume in active region achieved high-speed direct modulation. The fabricated lasers in the array lase with different wavelengths with stable single-longitudinal mode. Clear eye-opening and large mask margin were obtained in push-pull driving at 25.8 Gb/s direct modulation with coplanar electrode and semi-insulating InP substrate. Comparison of modulation waveform under simultaneous operation of neighbor lasers shows that crosstalk between lasers in the array is small. Clear eye-openings, large mask margins, and 10-km fiber transmission of four different wavelength lasers on LAN-WDM grid are demonstrated under 28-Gb/s operation at 50 °C. For further high-speed operation, 43-Gb/s direct modulation were performed. These results indicate that the 1.3-μm AlGaInAs DR laser arrays are promising as light sources for 100-Gb/s Ethernet and higher speed transmission.

Simultaneous 40-Gbps direct modulation of 1.3-µm wavelength AlGaInAs distributed-reflector laser arrays on semi-insulating InP substrate

40-Gbps direct modulation of 1.3-μm wavelength AlGaInAs distributed-reflector laser arrays on semi-insulating InP substrate are investigated. Clear eye-opening is demonstrated under simultaneous operation of two lasers.

High-Speed Wavelength Tuning of Tunable Distributed Amplification DFB-LD in Long Haul Transmission

We clarified for the first time the influence of tuning current noise on linewidth broadening and transmission for TDA-DFB-LD. Suppressing noise at higher frequencies, we demonstrated 300-ns high-speed wavelength switching without degradations in 80-km transmission.

High-Speed Directly Modulated Distributed-Reflector Lasers

High-speed directly modulated single-mode lasers are attractive light sources for compact, low-power-consumptive optical modules. For next-generation optical modules, attempts for higher modulation speed at high temperatures are energetically studied.