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In this paper, we describe high-speed 1.1-μm-range oxide-confined vertical-cavity surface-emitting lasers (VCSELs) for large-scale optical interconnection applications. For achieving high data rates up to 25 Gbit/s under high temperature, we applied InGaAs/GaAsP strain-compensated multiple quantum wells (SC-MQWs) as the active layer. The developed device showed 25 Gbit/s error-free operation at 100°C. We also examined reliability of the VCSELs through accelerated life tests. The result showed an extremely long lifetime of about 10 thousand hours in MTTF under an ambient temperature of 150°C and a current density of about 19 kA/cm2. The level of reliability either equaled or surpassed that of conventional 0.85-μm VCSELs. Moreover, we revealed a typical failure mode of the device, which was caused by ≪110≫ dark line defects (DLDs) generated in the n-DBR layers under the current aperture area.

Necropsy and histopathologic examination of three Great Cormorants (Phalacrocorax carbo) shot in Niigata, central Japan, revealed goitrous changes in the thyroids. Thyroids had a hypertrophic follicular epithelium, loss or deficiency of luminal colloid, occasional small follicles suggesting hyperplasia, and occasional collapsed follicles. Irregularly shaped follicles were frequent, and hyperemia, deposition of dark pigment, and sporadic lymphoid aggregates were also seen. Chemical analysis simultaneously conducted showed higher than normal levels of dioxins in the liver, muscle, and fat, i.e., polychlorinated dibenzo-dioxins, polychlorinated dibenzo-furans, and coplanar polychlorinated biphenyls. The present results, together with those of relevant previous studies, strongly suggest an association between these pollutants and thyroid lesions in the Great Cormorant.

We have developed InGaAs-based VCSELs operating around 1.1µm for high-speed optical interconnections. By applying GaAsP barrier layers, temperature characteristics were considerably improved compared to GaAs barrier layers. As a result, 25Gbps 100°C error-free operation was achieved. These devices also exhibited high reliability. No degradation was observed over 3, 000 hours under operation temperature of 150°C and current density of 19kA/cm2. We also developed VCSELs with tunnel junctions for higher speed operation. High modulation bandwidth of 24GHz and a relaxation oscillation frequency of 27GHz were achieved. 40Gbps error-free operation was also demonstrated.

Serum antibodies reactive with recombinant Sm-hPAF (rSm-hPAF) and synthetic peptide subunits (N-terminal portion of Sm-hPAF) were measured by ELISA in patients with Kawasaki disease (KD) compared with other febrile diseases and healthy subjects (control groups). The antibody titers to rSm-hPAF and a synthetic peptide representing the N-terminal 186–205 amino acid residues in the sera from patients with KD were significantly higher than those in the sera from two control groups. Measurement of the presence of anti-rSm-hPAF and anti-synthetic peptide portion antibodies may provide a tool in the serological diagnosis of KD (acute phase).

Seven Japanese patients on maintenance hemodialysis who were comorbid with mild depression were medicated with 50 mg/day fluvoxamine maleate for 28 days. Effectiveness was obtained in four out of seven patients (57%). The plasma fluvoxamine concentrations were examined in three patients. The plasma fuvoxamine concentration decreased by 22% by hemodialysis. There is a tendency for the dialyzed rate of fluvoxamine to become lower if the plasma albumin concentration is higher. The half-life of fluvoxamine was possibly shortened more in the patient with hypoalbuminaemia. The plasma fluvoxamine concentration reached a steady state 8 days after the start of medication and thereafter. The time required to reach steady state was lengthened when compared with the results in normal Japanese volunteers.

We have developed a novel three-dimensional high precision self-aligned assembly using stripe-type Au-Sn solder bumps and a micro-press solder bump formation method. This produces a high bonding precision of 1 /spl mu/m for optical device assembly in both lateral and vertical directions without the need for time-consuming optical axes alignment. Furthermore, we tested a hybrid integrated 4/spl times/4 optical matrix switch, in which multiple SSC-SOAG arrays were simultaneously positioned and optical fibers were passively positioned on a silica based PLC platform using this technology. Four optical chips and seven wiring chips are assembled on a planar lightwave circuit (PLC) platform. The insertion loss for each of these paths at an injection current of 40 mA was within a range of 9/spl plusmn/4 dB. The average extinction ratio was 40 dB. This self-aligned assembly technology was shown to be useful for building hybrid-integrated multichannel optical network components.

A spot-size converter integrated semiconductor optical amplifier (SSC-SOA) was developed as a gate element in an optical switch matrix for photonic switching applications. By a selective metal-organic vapor phase epitaxy technique, a bulk InGaAsP stripe, including an active region and thickness tapered SSCs, was grown. Wavelength composition of the stripe, strain on the stripe, and electrode coverage above the SSC region were optimized. As a result, gate operation for fiber-to-fiber gain of 0 dB was achieved at a low injection current of 30 mA, and the polarization dependence of the gain was eliminated as well.

We developed 1.1-mum-range vertical-cavity surface-emitting lasers based on InGaAs-GaAs quantum wells, back-illuminated InGaAs photodiodes, and transimpedance amplifiers (InP heterojunction bipolar transistor) for high-speed optical interconnection. Clear eye opening operation and error-free transmission at 30 Gb/s over 100-m multimode fibers (GI32) were successfully achieved for the first time.

We propose 1.1-µm-range InGaAs quantum-well (QW) vertical-cavity surface-emitting lasers (VCSELs) with a buried type-II tunnel junction (BTJ). Because of the low electrical resistance of the type-II tunnel junction, the chip resistance was reduced by over 40% compared with conventional oxide-confined VCSELs with the same-size aperture. In an aging test, stable operation at 85 °C was maintained in terms of optical and electrical characteristics for over 1000 h without early failure. The introduction of the type-II TJ structure can suppress self-heating caused by the chip resistance and may be a practical approach to achieving high-speed VCSELs for advanced optical interconnection.

We report the first atmospheric-pressure narrow-stripe (

We have developed vertical-cavity surface-emitting lasers for optical interconnections operating at 1.07 mum. The active layers of the devices are InGaAs-GaAs multiple quantum-wells, which are suitable for high-speed operation and high reliability. The devices exhibit -3-dB modulation bandwidths up to 19 GHz and no degradation under 70degC, 1000-h automatic power control tests. Error-free 20-Gb/s operations were also achieved

Low-threshold operation was demonstrated for a 1.34-/spl mu/m vertical-cavity surface-emitting laser (VCSEL) with GaInNAs quantum wells (QWs) grown by metal-organic vapor-phase epitaxy. Optimizing the growth conditions and QW structure of the GaInNAs active layers resulted in edge-emitting lasers that oscillated with low threshold current densities of 0.87 kA/cm/sup 2/ at 1.34 /spl mu/m and 1.1 kA/cm/sup 2/ at 1.38 /spl mu/m, respectively. The VCSEL had a low threshold current of 2.8 mA and a lasing wavelength of 1.342 /spl mu/m at room temperature and operated up to 60/spl deg/C.

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.

A wide-band wavelength-selectable light source module having an integrated multiwavelength locker has been developed. An eight-distributed-feedback (DFB) arrayed monolithic light source was designed to have 40-nm tunable range in the L-band by covering 5 nm per DFB laser diode. A uniquely designed etalon-based wavelength locker achieved very stable operation and uniform locking performance for all channels. Wavelength variation in the short term at room temperature was much less than 1 pm and the locked wavelength stayed within +/-5 pm when the case temperature of the module was varied from -20/spl deg/C to 65/spl deg/C.

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.

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.

A uniform and high performance eight-channel spot-size-converter integrated SOA (SSC-SOA) array for optical switching gate applications is demonstrated. Bow-shaped waveguides are used to achieve high gain and high ON-OFF ratio switching. All channels of the fabricated eight-channel array show a high fiber-to-fiber gain of 12.7 dB, low polarization-dependent gain (PDG) of 50 dB at a low drive current of 40 mA.

We have developed compact 12-channel, on-board optical transmitters and receivers. The assembly size was 9 mm × 14 mm. Error-free transmission up to 20 Gb/s/ch was achieved, which will enable us to construct a high density optical interconnect.

We have developed a hybrid-integrated symmetric Mach-Zehnder all-optical switch and evaluated the demultiplexing of 168-Gb/s data pulses at a repetition rate of 10 GHz with this switch. A compact, stable device was realized by assembling semiconductor optical amplifiers as nonlinear waveguides on a planar lightwave circuit in a self-aligned manner. A 6.0-ps switching window needed for 168-Gb/s demultiplexing was provided by the push-pull operation of the symmetric Mach-Zehnder all-optical switch. Demultiplexed signal light showed a high extinction ratio of better than 18 dB. Error-free demultiplexing with a bit error rate of 10/sup -11/ was achieved.

In this paper, we describe high temperature operation of high speed 1.1μm-range oxide-confined vertical-cavity surfaceemitting lasers (VCSELs) for optical interconnection applications. For achieving high speed of over 25 Gbit/s under a high temperature, we applied InGaAs/GaAsP strain-compensated multiple quantum wells (SC-MQWs) as the active layer. The developed device showed 25 Gbit/s error-free operation at 100°C. We also examined reliability of the VCSELs via accelerated life tests. The result showed extremely long MTTF lifetime of about 10 thousand hours under an ambient temperature of 150°C and a bias current of about 19 kA/cm 2 , a reliability that either equals or surpasses that of conventional 850-nm VCSELs with 10 Gbit/s. Moreover, we revealed a typical failure mode of the device; the result of analysis indicated that the failure was caused by dark line defects (DLDs) generated in the n-DBR layers under the current aperture area.

The extinction ratio of an optical gate with a spot-size-converter-integrated semiconductor optical amplifier (SSC-SOA) is deteriorated following the direct coupling of unguided light between the input and output fibers. In this letter, an S-bend waveguide structure is introduced into an active waveguide to suppress such direct coupling. Angled facet structures are also introduced for obtaining low facet reflectivity. The fabricated SSC-SOA operating at 1.55-/spl mu/m wavelength achieves an extinction ratio up to 70 dB and a fiber-to-fiber gain of 20 dB.

We developed 1.1-mum-range oxide-implant VCSELs with InGaAs/GaAsP strain-compensated MQWs. 25 Gbit/s-100degC error-free operation and high reliability over 3000 hours under 150degC operation were successfully demonstrated.

We have developed 1.1-μm-range high-speed VCSELs based on InGaAs-QWs for high-speed and highly reliable optical interconnections. 3-dB bandwidth up to 20 GHz and error-free 30-Gbps 100 m operations were demonstrated with oxide confined VCSELs. We also developed buried tunnel junction VCSELs to further improve the relaxation oscillation frequency limit. 3-dB bandwidth up to 24 GHz and error-free 40-Gbps operations were demonstrated with these VCSELs.

Recently low-cost optical links for home and car networks have been extensively developed under the continuous need for expanding transmission capability. Popular low-cost optical links based on red-LEDs and 0.85-μm VCSELs mainly handle bit rates below 1 Gbit/s. In this paper, we demonstrate 6 Gbit/s optical data transmission under a wide temperature range from -40 to 115°C, using low-cost plastic-mold Transmitter (Tx) and Receiver (Rx) leadframe modules. The high transmission rate can handle high-definition television signals, and the expanded operating temperature range is applicable even for roof modules in automotive applications.

We demonstrate 30-Gb/s transmission using 1.1 μm-range VCSELs based on InGaAs/GaAs quantum wells, back-illuminated InGaAs PDs, and TIAs (InP-HBT). Error-free 30-Gbps transmission with 100 m-MMFs (GI32) is achieved for the first time.

We developed VCSELs based on InGaAs-QWs for high-speed optical interconnections. Error-free operations were achieved up to 25 Gbps. We also proposed VCSELs with type-II tunnel junctions to reduce electrical resistance for higher speed operation.

We propose 1.1-μm-range VCSELs with buried Type-II tunnel junctions (BTJs). Due to the small electrical resistance of the Type-II tunnel junction, the chip resistance was reduced by half as compared with oxide confined VCSELs. The BTJ-VCSELs were lased up to 120°C.

In this work, 1.1-/spl mu/m-range VCSELs based on InGaAs/GaAs quantum wells with high modulation bandwidth up to 20 GHz were developed. Error-free 25-Gbps operations were achieved for the first time using directly modulated multimode VCSELs.

Vertical cavity surface emitting lasers (VCSELs) for optical interconnections operating at 1.07 mum have been developed. Active layers of the devices are InGaAs/GaAs MQWs, which are suitable for high-speed operation and high reliability. The devices exhibit -3 dB modulation bandwidths up to 19 GHz and no degradation under 70degC 1000 hour APC tests

This paper reports on the performance of the four-wavelength 10-Gb/s GaInNAs VCSELs for a 40-Gb/s CWDM system. WDM transmission characteristics using a optical multiplexer and a demultiplexer including dielectric thin film filters is also demonstrated.

A new-type 10-Gbps VCSEL-TOSA (vertical cavity surface emitting laser transmitter optical sub-assembly) was demonstrated with single-mode-fiber direct coupling optics and a flexible substrate platform. The TOSA showed high fiber coupling efficiency (-1.6 dB) and clear 10-Gbps eye-opening with -2.6 dBm average optical power and 6 dB extinction ratio.

We have developed eight-DFB-LD-array WSLs having a novel integration structure that uses a selectively-grown microarray active waveguides directly connected to dry-etched passive waveguides. We have first demonstrated an entire coverage of 100-GHz-spaced 135 ITU-T grids over the S-, C-, and L-bands by using only six WSLs fabricated on two wafers. High device performances such as more than 15-nm /spl Delta//spl lambda/, P/sub f/ of over 9 mW, and an SMSR of more than 42 dB were also shown. The practical properties of the WSLs over the three bands will increase the transmission capability of multi band DWDM systems.

We have first reported on a 94-channel wide-band WSL installed in a 22-pin butterfly package with a multi-wavelength locker. We could realize 40-nm operation in the L-band for an 8-DFB arrayed monolithic WSL by covering 5 nm per DF3-LD. By using a monolithically integrated WSL and minimizing the number of components on the wavelength locker we could install all function in a 12.7-mm /spl times/ 20.8-mm standard butterfly package. This WSL module with a stable-wavelength operation and uniform locking performance is a promising development to provide a large degree of flexibility in DWDM system design.

The cavity-length dependence of the nonlinear-phase-shift of semiconductor optical amplifier (SOA) phase shifters was experimentally investigated for a symmetric-Mach-Zehnder-type wavelength-converter for the first time. Studies of 42-GHz-cross-phase-modulation of SOAs showed that the phase-shift increased almost proportionally with active region length.

Angled facet spot size converter integrated semiconductor optical amplifiers (SSC-SOAs) with S-shaped waveguides are developed as gate elements in optical matrix switches on planar lightwave circuits (PLC). A high fiber-to-fiber gain of +20 dB and a high extinction ratio of 70 dB are achieved.

We developed multi-range wavelength-selectable light sources (WSLs) with an all-selective MOVPE (ASM) grown microarray planar-buried-hetero (MPBH) structure. We simultaneously fabricated five WSLs, each with a unique 8-nm tuning range, to cover forty 100-GHz-spaced channels (the entire C-band). Uniform characteristics, such as an I/sub th/ of 8.3 /spl plusmn/ 1.2 mA, an SMSR of over 45 dB, and a fiber-coupled power up to 15 mW, were obtained.

The symmetric Mach-Zehnder (SMZ) all-optical switch is quite promising for various types of future high-speed all-optical processing. We have developed a hybrid-integrated SMZ all-optical switch and achieved the error-free demultiplexing of 168 Gbps data pulses.

Tunable/selectable-wavelength light sources are now beginning to play important roles in dense wavelength-division multiplexing (DWDM) optical transmission systems. Among the many types of the light sources, we have been developing distributed-feedback (DFB) laser-diode (LD)-array-based 'wavelength-selectable' light sources (WSLs), because of their stable and reliable wavelength properties. This paper reviews our recent progress with WSLs devices and WSL modules for wide-band DWDM applications. We start by describing eight DFB-array WSLs, each of which has a tunable wavelength range (Dl) of 15 nm. We took full advantage of an advanced form of selective metal-organic-vapor-phase epitaxy, which we call microarray selective epitaxy (MASE), in fabricating WSLs of six types on two wafers to fully cover the S-, C-, and L-bands. These WSLs demonstrated high fiber output power of up to around 10 mW and had stable single-mode properties. We also describe a 94-channel (50-GHz spacing) WSL module with an integrated multi-wavelength-locker. A wide-band WSL with a Dl of 40 nm for the L-band, was installed with a compact wavelength locker in a standard-sized 22-pin butterfly package. The WSL module showed a stable locking performance of within a 1-GHz range over time and against variations in temperature.

The noise figure of a semiconductor optical amplifier is evaluated, focusing on its unput-power dependence, for application to a Tb/s optical packet/cell-based switching fabric.

SOA gate modules of 1.55-μm wavelength were fabricated for matrix switching. A low operating current of 9.7 mA on average and extinction ratios of more than 40 dB were achieved over 80 modules.

Reliability of both high-speed vertical-cavity surface-emitting lasers (VCSELs) with silicone-encapsulated structure and the parallel optical transmitter modules were investigated. Results of wear-out life tests indicated that the VCSEL with a silicone-encapsulated structure has the same lifetime as a bare-chip VCSEL, which was more than 106 h at the junction temperature of 90 °C. High reliability of the 20 Gbps × 12 channel on-board parallel optical transmitter modules in various test environments was also confirmed.