E. Omura

150 mW fundamental-transverse-mode operation of 670 nm window laser diode

Fundamental-transverse-mode high-power CW operation over 150 mW has been realized in AlGaInP/GaInP 670-nm window laser diodes. A window structure of Zn-induced-disordered GaInP has been fabricated by solid phase diffusion using ZnO film. A compressively strained double-quantum-well active layer and a multiple quantum barrier (MQB) also have been employed for reduction of threshold current. Stable CW operation beyond 1500 h has been observed under 50 mW at 50 degrees C. >

0.78- and 0.98-/spl mu/m ridge-waveguide lasers buried with AlGaAs confinement layer selectively grown by chloride-assisted MOCVD

The 0.78- and 0.98-/spl mu/m buried-ridge AlGaAs laser diodes (LDs) with a high Al-content AlGaAs confinement layer selectively grown by using a Cl-assisted MOCVD are demonstrated. By employing the AlGaAs confinement layer, the threshold current and the slope efficiency of the 0.78-/spl mu/m LD are improved by /spl sim/40%, compared to those of the conventional loss-guided LD with the GaAs confinement layer. In addition, the stable fundamental mode up to 150 mW and the small astigmatic distance less than 1 /spl mu/m are obtained. The 0.78-/spl mu/m LD also shows the excellent high-power and high-temperature characteristic such as 100 mW CW operation at 100/spl deg/C and the reliable 2,000-hour operation under the condition of 60/spl deg/C and 55 mW. In the 0.98-/spl mu/m LD, the narrow beam with the low aspect ratio of 1.86 and the stable fundamental transverse mode over 200 mW are exhibited. As a result, the 0.98-/spl mu/m LD realizes the high fiber-coupled-power of 148 mW. Moreover, the high-power and high-temperature operation of 150 mW at 90/spl deg/C is obtained. In the preliminary aging test, the LDs have been stably operating for over 900 hours under the condition of 50/spl deg/C and 100 mW. >

High-power 980-nm ridge waveguide laser diodes including an asymmetrically expanded optical field normal to the active layer

We propose a new ridge waveguide laser diode (LD) which supports an asymmetrically expanded optical field normal to the active layer in order to increase the maximum kink-free output power and reduce the aspect ratio of output beams. The dependence of maximum kink-free output power on facet reflectivity was analyzed from the viewpoint of the total optical power in the cavity. It was clarified that the maximum kink-free output power is influenced by the facet reflectivity which affects the refractive index changes of the ridge region via the total optical power in the cavity. More than 600 mW of maximum kink-free output power and an aspect ratio of less than 2.5 were achieved in experiments with 980-nm ridge waveguide LDs by means of this proposed new structure.

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.

1.3 /spl mu/m uncooled AlGaInAs-MQW DFB laser with /spl lambda//4-shifted grating

1.3 /spl mu/m uncooled AlGaInAs DFB-LDs with /spl lambda//4shifted grating have been successfully demonstrated. Relaxation oscillation frequency as high as 11.5 GHz has been obtained. Clear opening in the eye diagram under 10 Gbps direct modulation at 75/spl deg/C has been also confirmed. Preliminary life test over 5000 hours with no failure indicates its excellent reliability. The 1.3 /spl mu/m AlGaInAs DFB-LD with /spl lambda//4-shift grating is promising for the next generation high-speed data link systems such as 10 Gbps Ethernet.

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.

Over 200-mW operation of single-lateral mode 780-nm laser diodes with window-mirror structure

The high-power operation of the lateral mode stabilized 780-nm AlGaAs laser diode (LD) with the window-mirror structure has been achieved. The stable lateral mode operation up to 250 mW is realized. This is the highest power record among the narrow stripe LDs with the wavelength of 780 nm. This LD is suitable for the next generation high-speed (16-24/spl times/) CD-R/RW drives needing 200 mW class LDs.

40 GHz modulation bandwidth of electroabsorption modulator with narrow-mesa ridge waveguide

We have developed the EA modulator with narrow-ridge waveguide to obtain the sufficient extinction ratio with the shorter modulators. Narrowing the waveguide reduces device capacitance from 0.12 pF to 0.08 pF without decrease of the extinction ratio. The modulation bandwidth of 40 GHz at -1 V bias voltage, and the extinction ratio of 15 dB at 0 V to -2.5 V operation voltage are obtained. From the viewpoint of frequency bandwidth and extinction ratio for practical use, it may be concluded that the narrow mesa waveguide structure is suitable for 40 Gb/s optical transmitter devices.

1.3 /spl mu/m AlGaInAs ridge waveguide lasers with uncooled 10 Gb/s operation at 85/spl deg/C

We have realized 1.3 /spl mu/m MQW AlGaInAs lasers with 10 Gb/s operation even at high temperature of 85 C. This performance is well suitable for the uncooled high-speed transmission in optical communication systems, especially for gigabit ethernet application.

Uniform and high-power characteristics of AlGaInP visible laser diodes and their four-element arrays fabricated on a three-inch /spl phi/ wafer

The versatile potential of a three-inch diameter wafer processing technology has been successfully demonstrated by the realization of a large number of 680 mn high-power laser diodes (LDs) and their individually addressable four-element arrays on a single wafer at one time. The excellent uniformities of the laser characteristics, such as threshold current, operating current, beam divergences and lasing wavelength have been obtained. The LDs have been operating stably for over 2500 hours under the condition of 60/spl deg/C and 30 mW. In the four-element LD arrays with a junction-up configuration, the linear power-current (P-I) characteristics have been obtained up to 50 mW, even at 50/spl deg/C for each element. Moreover, the thermal crosstalk, defined as the output decrease rate caused by the temperature rise due to neighboring elements operation of 2.9-11.1%, has been realized in the high-power simultaneous operation. >