K. Naniwae

Full C-band external cavity wavelength tunable laser using a liquid-Crystal-based tunable mirror

A compact full C-band external cavity wavelength tunable laser is proposed. The cavity contains a fixed etalon and makes use of a liquid-crystal-based tunable mirror. The measurement results show a tuning range of 35 nm with fiber coupled power of more than 15 dBm. The sidemode suppression ratio is higher than 50 dB over the whole range and the relative intensity noise is below -148 dB/Hz. The linewidth is in worst case 700 kHz.

Analysis of differential gain in InGaAs-InGaAsP compressive and tensile strained quantum-well lasers and its application for estimation of high-speed modulation limit

A simplified model that furnishes an intuitive insight for the change in quantum-well (QW) laser gain due to QW strain and quantum confinement is presented. Differential gain for InGaAs-InGaAsP compressive and tensile strained multi-quantum-well (MQW) lasers is studied using the model. The comparison between the calculated and experimental results for lattice-matched and compressive strained MQW lasers shows that this model also gives quantitatively reasonable results. It is found that the variance-band barrier height strongly affects the differential gain, especially for compressively strained MQW lasers. The tensile strained MQW lasers are found to have quite high differential gain, due to the large dipole matrix element for the electron-light-hole transition, in spite of the large valence-band state density. Furthermore, a great improvement in the differential gain is expected by modulation p doping in the tensile strained MQW lasers. The ultimate modulation bandwidth for such lasers is studied using the above results. >

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.

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.

Strain dependence of the linewidth enhancement factor in long-wavelength tensile- and compressive-strained quantum-well lasers

Values of the linewidth enhancement factor alpha in InGaAs/InGaAsP tensile- and compressive-strained quantum-well (QW) Fabry-Perot lasers are measured and compared to calculated values. The strain dependence of the measured values agrees with that of the calculated values: Values of alpha are smaller for tensile-strained QW lasers than for compressive-strained QW lasers, and alpha decreases with the increase of tensile or compressive strain. According to the model used in the calculation, short-wavelength-composition barriers reduce alpha in compressive-strained QW lasers, and alpha for such lasers is expected to be as low as that for the tensile-strained QW lasers.<<ETX>>

A compact external cavity wavelength tunable laser without an intracavity etalon

We propose a novel external cavity wavelength tunable laser (ECTL) configuration without an etalon inside the cavity. ECTL consists only of a semiconductor optical amplifier with an integrated phase section, and a liquid crystal tunable mirror. We successfully demonstrated excellent performances of the ECTL with fiber coupled output power of more than 50 mW over a 40-nm tuning range, sidemode suppression ratio of better than 45 dB, relative intensity noise of better than -148 dB/Hz, and linewidth of narrower than 2.3 MHz

10-Gb/s - 120-/spl deg/C operation of 1.3-/spl mu/m AlGaInAs-MQW-FP-LD with Ru-doped InP buried heterostructure

We have developed the first 1.3-mum AlGaInAs-MQW-FP-LD with Ru-doped InP buried heterostructure by narrow-stripe selective MOVPE. SIMS measurements revealed that the Ru-doped InP suppressed Zn diffusion from Zn-doped InP in comparison with Fe-doped InP. The LD operates up to 170degC. 10-Gb/s operation up to 120degC and more than 3500-hour reliability under 85-degC APC test has been successfully achieved

Novel Active Multi-Mode-Interferometer (MMI) Laser Diodes Integrated with 1st Order-Mode Permitted Waveguides

We propose novel active multi-mode-interferometer laser diodes (LDs), integrated with 1storder-mode permitted waveguides. They achieved regular single-transverse-mode and high output power of 1.46W.

Cleaning of residual silicon on InP regrowth interface in MOVPE reactor

Investigating the use of tertiarybutylchloride (TBCl) to clean residual silicon from InP regrowth interfaces in an MOVPE reactor, we found the amount of the residual silicon to be greatly decreased when trimethylindium was supplied together with TBCl in order to balance the etching rate and the growth rate during the cleaning process. Using this cleaning process in the fabrication of buried hetero-structure laser diodes, we demonstrated that it improves their light-current characteristics by reducing the leakage current in the devices.