Yasumasa Kashima

Performance and reliability of InGaAsP superluminescent diode

The performance and reliability of a 1.3- mu m superluminescent diode (SLD) with a novel structure are reported. A window structure with a tapered active layer is applied to suppress lasing oscillation. A V-groove structure is introduced to achieve high coupling efficiency into a single-mode fiber. The design of optimized device dimensions allows SLD operation to be obtained even at 0 degrees C. 1.3 mW is coupled into a single-mode fiber at 150 mA and 25 degrees C. The spectral modulation depth is 15% over the entire emission spectral width of 32 nm. The operating life of a SLD has been estimated from the results of accelerated aging carried out for 5000 h at the ambient temperatures of 50 and 125 degrees C. The activation energy of degradation is estimated to be 0.58 eV, and the extrapolated life is 10/sup 6/ h at an ambient temperature of 25 degrees C. >

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.

Linear InGaAsP edge-emitting LED's for single-mode fiber communications

A 1.3- mu m edge-emitting diode with a linear radiance and high coupled power into a fiber is described. The LED yields 60 mu W of coupled power into a single-mode fiber at a driving current of 100 mA and an ambient temperature of 25 degrees C. A V-groove structure with an optical absorption region separated from an active region is used. At active layer thicknesses below 0.14 mu m, linear current-light output characteristics are obtained. The spectral modulation depth is 0% over the entire emission spectral width of 75 nm, and coherence length is 22.5 mu m. LED characteristics are achieved in the range from -30 to 85 degrees C at a driving current of 100 mA. The LEDs exhibit a cutoff frequency of 250 MHz. LED reliability is discussed using results of accelerated aging carried out at the ambient temperatures of 50, 125, and 200 degrees C. The activation energy of degradation is determined to be 0.63 eV, and LED half-lives are estimated to be in excess of 10/sup 6/ h. >

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.

Performance of multiple quantum well edge-emitting LED

This paper describes a 1.3-micrometers edge-emitting LED (light-emitting diode) with multiple quantum well structure. We introduce quantum well structure to the emission region in order to improve the thermal stability of the optical output power. The least temperature dependence and the highest optical output power are obtained at ten quantum wells. In the range from -30 degree(s)C to 85 degree(s)C, the temperature coefficient of the optical output power and the peak wavelength are - 0.87%/ degree(s)C, 0.52 nm/ degree(s)C, respectively. The LED yields a coupled power of 20 (mu) W into a single-mode fiber at a driving current of 100 mA and 25 degree(s)C.

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.

High-power 1.625-μm strained multiple-quantum-well lasers as a light source for optical time-domain reflectometers

An optical output power of 160 mW has been successfully achieved in 1.625-μm strained multiple-quantum-well lasers at a forward current of 800 mA under pulsed operation. Such a high output power has been achieved by optimizing the separated confinement heterostructure layer thickness. The operating life of high-power 1.625-μm lasers has been estimated from the results of accelerated ageing at an ambient temperature of 45°C and 500 mA under continuous-wave operation. No significant change in the optical output power was observed up to 2000 hours. The mean time to failure is estimated to be about 4.5×104 hours at 500 mA and 45°C.

Optical Properties of InGaAsP Multiple Quantum Well Edge-Emitting Light-Emitting Diode.

Effects of the number of wells on the characteristics of a 1.3-µ m edge-emitting light-emitting diode (LED) are investigated. The edge-emitting LED with 10 quantum wells had the highest optical output power at 100 mA and the lowest temperature coefficient of the optical output power in the temperature range from 10 to 75°C. The experimental result shows that the multiple quantum well structure improves the thermal stability of the optical output power.

1.55-μm superluminescent diode for a fiber optic gyroscope

We have developed a 1.55um superluminesent diode using a revolutionary structure. A light diffusion surface is placed diagonally on the active layer within the device to suppress the lasing action, and V—groove structure is applied to achieve high coupling efficiency into a single—mode fiber. Superluminescent diode characteristics were achieved in the range from 0 to 50C, and the coupled power into a single—mode fiber reached 0.5mW.