Tsutomu Munakata

1.3-μm AlGaInAs-AlGaInAs strained multiple-quantum-well lasers with a p-AlInAs electron stopper layer

1.3-/spl mu/m AlGaInAs-AlGaInAs strained multiple-quantum-well (MQW) lasers with a p-AlInAs electron stopper layer have been fabricated. The electron stopper layer was inserted between the MQW and p-side separate confinement heterostructure (SCH) layers to suppress the electron overflow from the MQW to p-SCH. The characteristic temperatures of the threshold currents and slope efficiencies were improved in the lasers with the stopper layers, especially at higher temperatures. As a result, a maximum operating temperature of 155/spl deg/C was achieved, which was 20/spl deg/C higher than that without the stopper layer.

Broad spectrum InGaAsP edge-emitting light-emitting diode using selective-area metal-organic vapor-phase epitaxy

We studied the effects of a composition-changing emission region on the emission spectrum using an InGaAsP multiple-quantum-well edge-emitting light-emitting diode (ELED). The ELED was fabricated by selective-area growth using a gradually changing mask stripe width. The spectral half-width exceeded 120 nm at an ambient temperature of 25/spl deg/C, offering a wider spectrum than that of conventional light-emitting diodes.

Thermal Properties of 1.3 µm AlGaInAs Multi Quantum Well Ridge Waveguide Lasers

We have fabricated 1.3 µm AlGaInAs/InP multi-quantum-well (MQW) ridge waveguide lasers with both junction-up and junction-down mounting, and compared the thermal resistance (Rth) and other laser characteristics such as the maximum CW operating temperature (Tmax), characteristic temperature of threshold current (T0), and the maximum CW output power (Pmax). The thermal resistance was found to be 73.6 K/W and 43.5 K/W for junction-up and -down mounting, respectively. T0, Tmax and Pmax were also improved by 7 K, 20°C and 20% in the junction-down configuration, respectively, which is due to a reduction of the thermal resistance. A CW Tmax as high as 185°C has also been achieved with 350-µm-long high-reflective-coated lasers, which is one of the highest CW operation temperature reported to date for InP-based long wavelength lasers.

Effects of well number on temperature characteristics in 1.3-/spl mu/m AlGaInAs/InP quantum well lasers

Effects of well number on temperature characteristics have been investigated in 1.3-/spl mu/m AlGaInAs-InP multiple-quantum-well (MQW) lasers. A record high pulsed operating temperature of 220/spl deg/C has been achieved in lasers with 10 QWs and a small power reduction of -1.68 dB between 20 and 80/spl deg/C has been obtained in lasers with 4 QWs.

1.3-/spl mu/m AlGaInAs/InP ridge-waveguide lasers with integrated beam-expanders

AlGaInAs lasers with integrated beam-expanders (IBEs) have been fabricated for the first time. The thickness of the multiple-quantum-well (MQW) active layers was vertically tapered by using selective area growth (SAG). A maximum operating temperature has reached 145/spl deg/C. The beam divergence in the vertical direction was drastically reduced from 41.7/spl deg/ (without IBEs) to 18.0/spl deg/ (with IBEs).

InGaAsP Multiple Quantum Well Edge-Emitting Light-Emitting Diode Showing Low Coherence Characteristics Using Selective-Area Metalorganic Vapor Phase Epitaxy

Low coherence multiple-quantum well edge-emitting light-emitting diodes were obtained using selective-area metalorganic vapor-phase epitaxial growth, which utilized growth rate enhancement on an open stripe region between mask stripes. An optical absorption region, which was controlled by selective-area growth, was introduced to suppress optical feedback. At a driving current of 100 mA and an ambient temperature of 25°C, a power of 55 μW was coupled into a single-mode fiber, and a broad spectrum without spectral ripple was observed. Low coherence characteristics and very small temperature dependence were obtained in the temperature range from -40°C to 85°C. The modulation bandwidth was 210 MHz at a bias current of 100 mA.

Effect of a p-AlInAs electron stopper layer in 1.3 /spl mu/m AlGaInAs/InP strained multiple quantum well lasers

We have investigated the effect of a p-AlInAs electron stopper layer (ESL) in 1.3-/spl mu/m AlGaInAs/InP strained multiple quantum well (MQW) lasers. The ESL was inserted between the MQW and p-side separate confinement heterostructure (SCH) layers to suppress the electron overflow from the MQW to p-SCH. The characteristic temperatures of the threshold currents and slope efficiencies were improved in the lasers with the stopper layers, especially at higher temperatures. As a result, a maximum CW operating temperature T/sub max/ was increased by 20/spl deg/C, and T/sub max/ of 210 and 170/spl deg/C under pulse and CW excitation was achieved, respectively.

High-temperature operation of 1.3-/spl mu/m AlGaInAs/InP strained multiple quantum well lasers with an AlInAs electron stopper layer

Summary form only given. Recently, AlGaInAs-InP lasers have been demonstrated to show superior temperature characteristics as compared to conventional GaInAsP/InP lasers, which is due to a larger conduction band offset of the AlGaInAs-InP systems and the resultant decrease in the electron overflow out of the multiple quantum well (MQW) active layers. In this study, we investigated the effect of the electron stopper layer (ESL) and observed a considerable improvement in the characteristic temperatures of the threshold current and slope efficiency, especially at higher temperatures, resulting in a higher operation temperature in the lasers with the ESL.

1.625-μm High-Power Strained Multiple Quantum Well Lasers for Optical Time-Domain Reflectometers

An optical output power exceeding 210 mW has been achieved using 1.625-μm strained multiple quantum well lasers at a forward current of 800 mA under pulsed operation. We introduced tensile-strained barrier layers to increase internal quantum efficiency. High quantum efficiency is attributed to improved of hole injection efficiency and suppressed electron overflow from wells. The 1.625-μm high-power lasers are expected to be applied to optical time-domain reflectometers, which enable regular communication light to be used.

1.625-um high-power lasers for OTDR monitoring systems for optical transmission lines

An optical power of over 160 mW has been successfully achieved using 1.625-micrometer strained multiple quantum well lasers at a forward current of 800 mA in pulsed operation. Such high power is achieved by optimizing the separated confinement heterostructure layer thickness. The operating life of high power 1.625-micrometer lasers has been estimated from the results of accelerated aging at 45 degrees Celsius, and 300 mA and 500 mA under continuous-wave operation. No significant change in optical output power was observed up to 4500 hours. The mean-time-to-failure at driving currents of 300 mA and 500 mA, at an ambient temperature of 45 degrees Celsius, are estimated to be about 4.2 multiplied by 104 hours and 3.5 multiplied by 104 hours, respectively.