Kenichi Kobayashi

Room‐temperature pulsed operation of AlGaInP/GaInP/AlGaInP double heterostructure visible light laser diodes grown by metalorganic chemical vapor deposition

Room‐temperature pulsed laser operation of (Al0.3Ga0.7)0.5In0.5P/ Ga0.5In0.5P/ (Al0.3Ga0.7)0.5In0.5P double heterostructure laser diodes grown by metalorganic chemical vapor deposition has been achieved for the first time. The lowest threshold current density was 26 kA/cm2 for a diode with a 22‐μm‐wide and 160‐μm‐long stripe. The lasing wavelength was 0.683 μm.

Continuous wave operation (77 K) of yellow (583.6 nm) emitting AlGaInP double heterostructure laser diodes

Continuous wave lasing operation with the shortest wavelength for semiconductor lasers was obtained from AlGaInP double heterostructure lasers at 77 K. The structure was grown by metalorganic vapor phase epitaxy. Lasing wavelength was 583.6 nm (yellow). Threshold current was 43 mA (1.9 kA/cm2). Magnesium was adopted as a p‐type dopant, and was proved to be preferable for a high aluminum composition AlGaInP cladding layer.

30-mW 690-nm high-power strained-quantum-well AlGaInP laser

A high-power 690-nm AlGaInP laser for use in a high-density rewritable-optical-disk memory system is presented. The deterioration of its temperature characteristics, which results from the high-power-oriented laser structure, is improved by using compressively strained GaInP quantum wells as the active layer. Output power of 40 mW is achieved up to 80 degrees C. Stable fundamental-transverse-mode operation is obtained up to 50 mW. Output-power-induced facet degradation is suppressed by an Al/sub 2/O/sub 3/ facet coating. The lasers operate stably at 30 mW at 50 degrees C for over 2600 h. The mean extrapolated lifetime is 10000 h. >

Real index-guided AlGaInP visible laser with high-bandgap energy AlInP current blocking layer grown by HCl-assisted metalorganic vapor phase epitaxy

We establish selective area growth of Al/sub x/In/sub 1-x/P and develop a high power 685-nm real index-guided AlGaInP visible laser for the first time. This laser has a high-bandgap energy Al/sub 0.5/In/sub 0.5/P current blocking layer, which is selectively grown by HCl-assisted metalorganic vapor phase epitaxy (MOVPE). Threshold current is reduced and slope efficiency is improved, compared with conventional lasers with GaAs current blocking layers. The threshold current and slope efficiency for a real index guided AlGaInP laser are 36 mA and 1.0 W/A, with a cavity length of 710 /spl mu/m. Fundamental transverse mode operation up to 50 mW, and CW operation over 55 mW at 25/spl deg/C, without any kinks in the light output power versus current curve, are achieved. This laser is operated stably for more than 1000 hours at 30 mW constant output power, at 50/spl deg/C. >

626.2‐nm pulsed operation (300 K) of an AlGaInP double heterostructure laser grown by metalorganic chemical vapor deposition

Room‐temperature pulsed laser operation of (Al0.55Ga0.45)0.5In0.5P /(Al0.17Ga0.83)0.5In0.5P / (Al0.55Ga0.45)0.5In0.5P double heterostructure laser diodes grown by metalorganic chemical vapor deposition has been achieved. The lasing wavelength is 626.2 nm, which is the shortest ever reported for an AlGaInP double heterostructure laser. Threshold current density is 50 kA/cm2 for a diode with a 20‐μm‐wide and 200‐μm‐long stripe.

Transverse Mode Stabilized 670Nm Atgainp Visible-Light Laser Diodes

Transverse mode stabilized AIGaInP visible light laser diodes are described and their high power operations are discussed. The laser structure applied for transverse mode stabilization is a ridge shape self-aligned structure, which is designed taking fabrication reproducibility into consideration. A very thin GaInP etching stopper layer is introduced in order to enable easy and accurate control of the dimensions of the self-aligned structure. Threshold current is about 30-50mA. Over 10mW output power is obtained for LDs with as-cleaved facets. Output power is limited by COD (catastrophic optical damage). COD power level under continuous-wave (cw) operation is estimated to be 1.4-1.7MW/cm2. After facet-coating, a stable fundamental mode operation, up to 20mw (cw), and maximum output power 31mW (cw), which is limited by COD, have been obtained. The lasing wavelength is 670nm.

Impedance, modulation response and equivalent-circuit of 650 nm surface emitting type light-emitting diode for POF data-links

Abstract The basic electrical equivalent circuit of an AlGaInP based 650xa0nm ring-LED proposed for plastic-optical fiber data-links is derived. The LEDs modulation bandwidth is found to be 65xa0MHz at a link average driving bias current of 35xa0mA. The LEDs modulation response is measured and shows an open-eye diagram for 156xa0Mbps non-return-to-zero (NRZ), pseudo-random signals with and without a peaking circuit, respectively.

Low-threshold 1.3-/spl mu/m AlGaInAs buried heterostructure laser diodes for 85/spl deg/C, 10-Gb/s operation

1.3-/spl mu/m AlGaInAs MQW BH laser diodes were fabricated by using an improved all-selective MOVPE developed for materials containing Al. Threshold currents as low as 9.0 mA and operation currents below 55 mA for a 10-mW output power at 85/spl deg/C were obtained in 250-/spl mu/m-cavity-length lasers whose front and rear facet reflectivities were respectively 30% and 95%. This is the first time that a relaxation oscillation frequency over 10 GHz and 10-Gb/s direct modulation were obtained at 85/spl deg/C when using AlGaInAs BH laser diodes.

Reliability consideration for AlGaInP laser diodes by automatic power control aging simulation

We develop an automatic power control aging simulation method for AlGaInP visible light emission laser diodes and apply it to aging tests of 650 nm wavelength AlGaInP lasers. A laser degradation expression, on which the simulation is based, is derived from automatic current control tests for 680 nm lasers. The simulation results agree well with the experimental results. The simulation is then used to show laser reliability (operation lifetime) as a function of laser initial characteristics (threshold current, characteristic temperature and the maximum cw temperature).

Self-sustained pulsation at 65/spl deg/C through reduced carrier overflow in AlGaInP laser diodes

Self-sustained pulsation at 65/spl deg/C under continuous-wave operation was obtained in AlGaInP laser diodes with a saturable-absorbing layer in part of the p-type cladding layer. The carrier overflow was significantly reduced to enable high-temperature performance by increasing the number of well layers in the active layer to four and increasing the compressive strain of the active layer (/spl epsiv//sub act/=+0.5%). The effect of the carrier overflow on self-sustained pulsation was investigated by analyzing the lasing spectrum and lasing polarization. The large amount of luminescence from the saturable-absorbing layer demonstrated that excessive carrier overflow at high temperature prevents the saturable absorbing layer functioning as an absorber.