Kenichiro Yashiki

1.55-μm wavelength-selectable microarray DFB-LD's with monolithically integrated MMI combiner, SOA, and EA-modulator

We developed compact (1.136 mm/sup 2/) eight-channel wavelength-selectable microarray distributed feedback laser diodes (DFB-LDs) with a monolithically integrated 8/spl times/1 multimode-interference (MMI) optical combiner, a semiconductor optical amplifier (SOA), and an electro-absorption (EA) modulator. By using /spl plusmn/10/spl deg/C thermal tuning, an addressable wavelength range of 15.3 nm with uniform device characteristics and 2.5-Gb/s modulation performance were successfully demonstrated.

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.

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

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

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

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.

MBE growth of ZnCdSe and MgZnCdSe alloys on InP substrates with a GaInAs buffer-layer

Abstract Molecular beam epitaxy growth of ZnCdSe and MgZnCdSe systems on (001) InP substrates were investigated. These films were grown on a lattice-matched GaInAs buffer-layer which was ex-situ grown on (001) InP by metalorganic vapor phase epitaxy. During the thermal cleaning process prior to II–VI film growth, group-V molecular beams were not used. By introducing this buffer-layer and lowering the initial growth temperature, the surface morphology of ZnCdSe films changed from rough to specular and the full width at half maximum (FWHM) of the double-crystal (004) X-ray rocking curves of the films decreased from more than 400 arcseconds to 60 arcseconds. The ZnCdSe film showed a very sharp excitonic emission in the 5 K photoluminescence spectra with a FWHM as narrow as 5.5 meV. No emission through deep levels was observed. High-quality MgZnCdSe films were also obtained using a GaInAs buffer-layer.

125-µm-pitch × 12-channel “optical pin” array as I/O structure for novel miniaturized optical transceiver chips

We have developed an optical I/O structure using an array of optical pins for a chip-scale parallel optical module named an “optical I/O core.” The optical pin is a kind of vertical polymer waveguide, which is made from UV curable resins. The optimum shape and combination of resins for the optical pins were determined by ray-trace simulation. The numerical aperture (NA) of the developed optical pins is more than 0.4. A photolithographic technique was used to produce a 125-μm-pitch × 12-channel optical pin array. The coupling losses between a GI-50 multi-mode optical fiber (MMF) and the optical pins for a receiver (RX) and transmitter (TX) were 0.41 dB and 2.3 dB, respectively. Wide coupling tolerance of more than 25 μm was also obtained when the allowable excess loss was 0.5 dB. Furthermore, clear eye diagrams were obtained for 25-Gbps back-to-back transmission by using the optical I/O cores with the optical pins and GI-50 MMF.

10-Gb/s 23-km penalty-free operation of 1310-nm uncooled EML with semi-insulating BH structure

We have developed a 1310-nm uncooled electroabsorption modulator integrated light source (EML) with an AlGaInAs multiple quantum well (MQW) active/absorption stripe, which was simultaneously grown using the narrow-stripe selective MOVPE technique and was buried with an Fe-doped InP. The Al-content MQW oxidation was effectively inhibited by using the same technique. An experiment-based evaluation of the devices performance revealed that by only changing the modulation bias voltage linearly with temperature, it was possible to achieve 10-Gb/s penalty-free operation at up to 85/spl deg/C over a 23-km single-mode fiber.

1.1-

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.

\mu

20-Gbps signal transmission of up to 100 m between two SERDES devices has been demonstrated using newly developed driver and receiver ICs tuned to the characteristics of VCSELs, photodiodes, and electrical transmission line with which they are used.