Katsuhiko Goto

Green, Orange, and Magenta Luminescence in Strontium Stannates with Perovskite-Related Structures

Intense green, orange or magenta luminescence was observed in rare-earth doped alkaline earth (Ca, Sr, and Ba) stannates, particularly strontium stannates with perovskite-related structures. Tb–Mg codoped SrSnO3 showed sharp emission lines corresponding to Tb ions as a green phosphor. Sm doped Sr3Sn2O7 exhibited sharp pairs of emission lines corresponding to Sm ions as an orange phosphor. Eu–Ti codoped Sr2SnO4 as a magenta phosphor showed sharp red luminescent lines corresponding to Eu ions as well as a broad blue emission band corresponding to Ti-related complexes. It was suggested that codoping and/or layered structures in these phosphors are closely related to the increase in luminescence intensity from these rare-earth ions.

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.

Narrow-beam and power-penalty-free 1.3-/spl mu/m laser diodes with monolithically integrated waveguide lens formed by selective-area epitaxial growth

A narrow-beam has been realized in a 1.3 /spl mu/m Fabry-Perot laser diode monolithically integrated with a tapered waveguide lens. The beam divergences in the perpendicular and horizontal directions are reduced down to 12/spl deg/ and 11/spl deg/ by a selective area epitaxial growth technique. The threshold current has been kept as low as 14 mA comparable to the conventional ones. Neither kinks in the L-I curves nor changes of far-field patterns are observed in the wide temperature range from -40 to 80/spl deg/C. Furthermore, high cut-off frequency over 4 GHz and power penalty-free characteristic under 622 Mb/s-50 km transmission have been confirmed.

2.5 Gb/s parallel transmission without excess bit error rate in a 1.3 /spl mu/m strained MQW LD array for optical interconnection

Summary form only given. 2.5 Gb/s parallel transmission has been successfully demonstrated using a 1.3 /spl mu/m strained MQW 10-element LD array. It is shown that the electrical crosstalk between neighboring LDs should be suppressed less than -20 dB at 2.5 GHz.

Zn-Diffusion-Induced Disordering of InGaAs/AlGaInAs Multiple Quantum Well and Its Application to Long-Wavelength Laser

Zn-diffusion-induced disordering of the InGaAs/AlGaInAs multiple quantum well (MQW) is investigated as a new processing technique for long-wavelength optoelectronic devices. Complete disordering of the MQW structure is confirmed through the observation of the shortening of the photoluminescence peak wavelength and secondary ion mass spectroscopy (SIMS) measurement. Lattice-matched disordering is also confirmed with X-ray diffraction. A long-wavelength buried-MQW laser is fabricated for the first time, in which index-waveguide and carrier confinement are obtained by disordering. The pulsed oscillation at room temperature is achieved near 1.56 µ m.

All-MOCVD-grown BH laser on P-InP substrates

A very low cw threshold current of 2.5 mA ( 25 degree(s)C) and 8.0 mA ( 80 degree(s)C) with high reliability has been realized in the all-MOCVD grown BH lasers on p-InP substrates. A strained MQW active layer of 1.3 micrometers wavelength and the precise carrier confinement buried structure by MOCVD is employed for the BH lasers. The excellent potential of long lifetime of the all-MOCVD grown laser has also been confirmed. After the high temperature and the high current (100 degree(s)C, 200 mA) aging test, no significant degradation is observed which is comparable with the well-established LPE grown lasers. The BH laser is also operating stably over 3700 hrs under the APC condition of 50 degree(s)C, 10 mW. Finally, an extremely uniform 10-element all-MOCVD grown LD array is demonstrated, which has the threshold current uniformity of 2.4 +/- 0.1 mA ( 25 degree(s)C) and 9.2 +/- 0.2 mA ( 80 degree(s)C). The growth mechanism in the MOCVD is also described.