Yoshiharu Muroya

Precise wavelength control for DFB laser diodes by novel corrugation delineation method

Precise wavelength control of a multiple-wavelength DFB InGaAsP strained MQW laser-diode (LD) array was achieved using weighted-dose allocation variable-pitch EB-lithography (WAVE) and highly uniform MOVPE. Multiple-wavelength 1.3 /spl mu/m /spl lambda//4-shifted DFB LD arrays with wavelength spacing of 2.0 nm were successfully demonstrated. The standard deviation of the wavelength was as low as 0.37 nm over 2-in wafers.

1.3-/spl mu/m AlGaInAs strain compensated MQW-buried-heterostructure lasers for uncooled 10-gb/s operation

We have successfully fabricated 1.3-/spl mu/m AlGaInAs strain-compensated multiple-quantum-well (MQW) buried-heterostructure (BH) lasers by narrow-stripe selective metalorganic vapor-phase epitaxy. Based on the optimization of AlGaInAs strain compensated MQW and the Al-oxidation-free BH process, we obtained a low-threshold current of 12.5 mA and a relaxation frequency of more than 10 GHz at 85/spl deg/C for Fabry-Perot lasers. For distributed feedback lasers, we demonstrated a 10-Gb/s operation and transmission of over 16 Km for a single mode fiber at 100/spl deg/C. Furthermore, a record-low 25.8-mA/sub p-p/ modulation current for a 10-Gb/s modulation at 100/spl deg/C was demonstrated with shorter cavity and high grating-coupling coefficient. A median life of more than 1/spl times/10/sup 5/ h at 85/spl deg/C was estimated after an aging test of over 5000 h for these lasers. These superior characteristics at high temperatures were achieved by the combination of the high differential gain of AlGaInAs strain compensated MQW and the BH structure.

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.

Low Drive-Current and Wide Temperature Operation of 1.3-μm AlGaInAs-MQW BH-DFB Lasers by Laterally Enhanced Cladding Layer Growth

Low drive-current and extremely wide temperature (from -45 to 105°C) operation were demonstrated in 10-Gb/s directly-modulated 1.3-μm AlGalnAs-MQW BH-DFB lasers with a new DH structure having a p-InP cladding layer grown by a lateral-growth technique.

Isolator-free 2.5-Gb/s 80-km transmission by directly modulated /spl lambda//8 phase-shifted DFB-LDs under negative feedback effect of mirror loss

It was verified for the first time that phase-shift value in directly modulated DFB laser diodes (LDs) affects their chirping characteristics and external optical feedback resistance due to the feedback effect of mirror loss (FEML). Theoretical and experimental results clarified that the negative FEML achieved in /spl lambda//8 phase-shifted DFB-LDs was able to improve the transmission performances and make the LDs more robust to external optical feedback. Isolator-free 80-km transmissions with a very low power penalty of less than 1-dB at bit error rate (BER)=10/sup -10/ was demonstrated with 2.5-Gb/s directly modulated 1.55-/spl mu/m /spl lambda//8 phase-shifted DFB-LDs.

Wavelength-selectable microarray light source with over 20-mW fiber-coupled power for 23 ITU-T channels

We have developed a wavelength-selectable light source (WSL) based on microarray DFB-LD configuration that enables high fiber-coupled power operation. The WSL was grown in only two steps without any complicated semiconductor etching. Using the WSL, fiber-coupled power of more than 20 mW and stable single-mode oscillations with an SMSR of more than 50 dB were obtained for all 23 addressable ITU-T channels on a 50-GHz grid.

Multirange wavelength-selectable microarray light sources simultaneously fabricated on a wafer covering the entire C-Band

We developed high-performance distributed feedback array-based wavelength-selectable light sources (WSLs), covering the entire C-band with five simultaneously fabricated devices. We fabricated five different range WSLs on a wafer, each with a unique 8-nm tuning range to cover 40 100-GHz-spaced channels. Uniform characteristics, such as an Ith of 8.3/spl plusmn/1.2 mA, a sidemode suppression ratio of over 45 dB, and a fiber-coupled power greater than 8.5 mW were obtained.

High-quality 1.3-/spl mu/m AlGaInAs MQW growth on a grating and its application to BH DFB-LDs for uncooled 10-Gb/s operation

A process for growing a high-quality AlGaInAs MQW on a grating has been developed and applied to fabricate a 1.3-/spl mu/m AlGaInAs BH DFB-LD. A low threshold current of 20 mA, a high slope efficiency of 0.31 W/A at 85/spl deg/C and a high CW operating temperature of 120/spl deg/C were obtained for a 250-/spl mu/m-long device with antireflective and high-reflective coated facets. A clear eye opening under 10-Gb/s direct modulation was also confirmed at 85/spl deg/C.

Wavelength-independent operation of EA-modulator integrated wavelengthselectable microarray light sources

In this letter, we have simultaneously fabricated five wavelength-selectable microarray light sources (WSLs), each having a different wavelength range integrated with an electroabsorption (EA) modulator on a single wafer. We also introduced a novel device configuration scheme for wavelength-independent modulation. The five EA-WSLs fully covered the entire C-band and had a low uniform threshold current of 6 /spl plusmn/ 1 mA at 25/spl deg/C. Wavelength-independent extinction characteristics were obtained over a tuning wavelength range of 8 nm, and 2.5-Gb/s transmission over 600 km was successfully achieved.

Isolator-free 2.5 Gb/s, 45 km transmission characteristics in partially corrugated waveguide laser diodes from -40/spl deg/C to 80/spl deg/C under -14 dB external optical feedback

Using partially corrugated waveguide laser diodes (PC-LDs) with robust and high-yield external optical feedback resistance, isolator-free 2.5-Gbit/s,45-km transmission was demonstrated over a wide temperature range from -40/spl deg/C to +80/spl deg/C under -14 db external optical feedback.