Naofumi Suzuki

High-speed 1.1-μm-range InGaAs VCSELs

We have developed 1.1-μm-range high-speed VCSELs based on InGaAs-QWs for high-speed and highly reliable optical interconnections. 3-dB bandwidth up to 20 GHz and error-free 30-Gbps 100 m operations were demonstrated with oxide confined VCSELs. We also developed buried tunnel junction VCSELs to further improve the relaxation oscillation frequency limit. 3-dB bandwidth up to 24 GHz and error-free 40-Gbps operations were demonstrated with these VCSELs.

Wavelength-selectable microarray light sources for S-, C-, and L-band WDM systems

We report on the first demonstrated near-complete coverage of the S-, C-, and L-bands using six different ranges of wavelength-selectable microarray light sources (WSLs) based on a distributed-feedback (DFB) laser diode (LD) array. The six devices were fabricated on only two wafers. Each device has a tuning range of more than 15 nm, a sidemode suppression ratio of over 40 dB, and a fiber-coupled power greater than around 10 mW.

Highly Reliable High-Speed 1.1-

In this paper, we describe high-speed 1.1-μm-range oxide-confined vertical-cavity surface-emitting lasers (VCSELs) for large-scale optical interconnection applications. For achieving high data rates up to 25 Gbit/s under high temperature, we applied InGaAs/GaAsP strain-compensated multiple quantum wells (SC-MQWs) as the active layer. The developed device showed 25 Gbit/s error-free operation at 100°C. We also examined reliability of the VCSELs through accelerated life tests. The result showed an extremely long lifetime of about 10 thousand hours in MTTF under an ambient temperature of 150°C and a current density of about 19 kA/cm2. The level of reliability either equaled or surpassed that of conventional 0.85-μm VCSELs. Moreover, we revealed a typical failure mode of the device, which was caused by ≪110≫ dark line defects (DLDs) generated in the n-DBR layers under the current aperture area.

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In this work, 1.1-mum-range VCSELs based on InGaAs/GaAs quantum wells with high modulation bandwidth up to 20 GHz were developed. Error-free 25-Gbps operations were achieved for the first time using directly modulated multimode VCSELs

m-Range VCSELs With InGaAs/GaAsP-MQWs

An advanced microarray-selective epitaxy with wider open-stripes has been developed for simple fabrication of distributed-feedback laser diode array-based high-power wavelength-selectable light sources. More than 40-mW fiber-coupled power and 50-dB sidemode suppression ratio over 9.2-nm wavelength were achieved.

25-Gbps operation of 1.1-/spl mu/m-range InGaAs VCSELs for high-speed optical interconnections

We have developed vertical-cavity surface-emitting lasers for optical interconnections operating at 1.07 mum. The active layers of the devices are InGaAs-GaAs multiple quantum-wells, which are suitable for high-speed operation and high reliability. The devices exhibit -3-dB modulation bandwidths up to 19 GHz and no degradation under 70degC, 1000-h automatic power control tests. Error-free 20-Gb/s operations were also achieved

Wavelength-selectable light sources fabricated using advanced microarray-selective epitaxy

We propose tunnel junctions with type-II heterostructures to reduce the electrical resistance of vertical-cavity surface-emitting lasers. We fabricated the type-II tunnel junctions on GaAs substrates, which consist of highly C-doped GaAsSb on the p side and highly Si-doped InGaAs on the n side. We achieved an extremely low specific resistance of 4×10−6Ωcm2, which corresponded to a resistance of 20Ω for an aperture 5μm in diameter. The specific resistance of the type-II tunnel junction was about 40% smaller than that of the type-I tunnel junction.

1.1-/spl mu/m-range InGaAs VCSELs for high-speed optical interconnections

We have developed novel 1.1-mum-range buried type-II tunnel junction vertical-cavity surface-emitting lasers (VCSELs) with a dielectric mirror for high-speed optical interconnections. A relaxation oscillation frequency of 27 GHz was achieved. The maximum 3-dB bandwidth was over 24 GHz. Error-free 30-Gb/s operation using a 27 -1-length pseudorandom bit sequence was demonstrated using directly modulated multimode VCSELs.

Low resistance tunnel junctions with type-II heterostructures

Low-threshold operation was demonstrated for a 1.34-/spl mu/m vertical-cavity surface-emitting laser (VCSEL) with GaInNAs quantum wells (QWs) grown by metal-organic vapor-phase epitaxy. Optimizing the growth conditions and QW structure of the GaInNAs active layers resulted in edge-emitting lasers that oscillated with low threshold current densities of 0.87 kA/cm/sup 2/ at 1.34 /spl mu/m and 1.1 kA/cm/sup 2/ at 1.38 /spl mu/m, respectively. The VCSEL had a low threshold current of 2.8 mA and a lasing wavelength of 1.342 /spl mu/m at room temperature and operated up to 60/spl deg/C.

1.1-

We have developed novel 1.1-μm-range InGaAs VCSELs with buried type-II tunnel junctions for high-speed optical interconnections. A relaxation oscillation frequency of 27 GHz was achieved. Error-free 30-Gbps operations were demonstrated using directly modulated multi-mode VCSELs.