Harumi Nishiguchi

Long-Wavelength Receiver Optoelectronic Integrated Circuit on 3-Inch-Diameter GaAs Substrate Grown by InP-on-GaAs Heteroepitaxy.

A monolithic long-wavelength receiver optoelectronic integrated circuit (OEIC), which integrates an InGaAs PIN-photodiode (PD) and a GaAs field-effect transistor (FET), has been successfully fabricated on a 3-inch-diameter GaAs substrate using InP-on-GaAs heteroepitaxy, by metalorganic chemical vapor deposition (MOCVD) and conventional GaAs-IC process technology. The epitaxial quality of the PD layer has been improved by use of a low-temperature-grown buffer layer, thermal cyclic annealing and an InGaAs/InP strained-layer superlattice. The integrated PD has low dark current of 10 nA at -5 V bias voltage, and exhibited stable operation at 175°C. The fabricated receiver OEIC has 1.4 GHz bandwidth and sensitivity of -28.1 dBm at the transmission rate of 622 Mb/s with bit error rate of 10-9, which is applicable to practical subscriber optical communication systems.

High-power red laser diode for recordable DVDs

A kink mechanism of a red (658nm) laser diode (LD) has been investigated in order to achieve a higher power operation of over 200mW. The experimental results indicate that a main origin of the kink generation is due to the deviation of the refractive index step caused by the local heat generation at the stripe region. To reduce the heat generation at the stripe region, an extension of a cavity length of the LD is applied. The LD with the cavity length of 1500μm realizes a kink-free 200mW operation even at 80°C. Also, this LD shows a reliable pulsed operation of 230mW at 75°C and 250mW at 70°C for over 1700 hours. This is the highest power operation among narrow stripe 658nm LDs.

High-efficiency and high-power laser diodes for CD-R/RW and DVD-RAM/RW

As light sources of CD-R/RW and DVD-RAM/RW, highly efficient high-power 785 nm (AlGaAs) and 660 nm (AlGaInP) lasers are demonstrated, respectively. A real-refractive-index waveguide with small internal loss is applied to both the lasers in order to reduce the operating current by improvement of the external differential quantum efficiency. The mirror degradation level is increased by reduction of the optical power density and/or a non-optical-absorbing effect of the window-mirror. As a result, the 785 nm window- mirror with AlGaAs current blocking layer has showed stable transverse mode operation up to 250 mW (kink level: over 300 mW at CW) with the high slope efficiency of 1.1 W/A. Reliable 140 mW-CW and 180 mW-pulse operation has been realized at 70 - 75 degree(s)C. As for a 660 nm laser with the window-mirror, the operation current at 70 mW is reduced by 40% due to the high slope efficiency (1.08 W/A) resulting from the low-loss ridge-waveguide. The lateral mode is well stabilized up to 70 mW by the effect of the narrow ridge stripe formed by a dry etching technique. Reliable 70 degree(s)C, 70 mW pulse (duty cycle: 50%) operation with a low operating current of around 120 - 140 mA has been achieved. In addition, the lasers have operated for over 1000 hours even at 70 degree(s)C, 80 mW.

Improvement of high power/high temperature operation of long wavelength laser diodes by band discontinuity reduction layer

50 percent increase of maximum output power and 25 percent decrease of operating current at 70/spl deg/C,5mW in long wavelength laser diodes have been realized by the introduction of intermediate composite layer between a cladding layer and an active layer.

Low threshold current coplanar vertical injection laser diode for optoelectronic integrated circuits

A low threshold coplanar vertical injection laser diode (CPVI-LD) has been newly developed utilizing impurityinduced disordering of a single quantum well. The threshold current as low as 13 mA has been realized in CW operation. The behavior of Si and Zn solid phase diffusion is precisely investigated for the realization of the CPVJ-LD.

Diodes with window-mirror structure

The high power operation of the lateral mode stabilized 785nm AlGaAs LD with the window-mirror structure has been demonstrated. The stable lateral mode operation up to 250mW (kink level of 280 mW) is realized. To the best our knowledge, this is the highest power record among the narrow stripe LDs with a wavelength of 785 nm and is suitable for CD ROM disc drives.

A long-wavelength InGaAs/AlGaInAs MQW laser fabricated by Zn-diffusion induced disordering

The authors have fabricated a long-wavelength InGaAs/AlGaInAs MQW (multiple quantum well) laser in which optical confinement and carrier confinement are produced by disordering of the MQW. Pulsed oscillation at room temperature has been attained in this disordered system. It is believed that the lattice matched disordering of the InGaAs/AlGaInAs MQW structure is a promising technique for realizing a long-wavelength planar-type laser structure and other optoelectronic devices such as OEICs (optoelectronic integrated circuits).<<ETX>>