H. Nishi

Fujitsu Ltd., Kawasaki Si, Kanagawa, Japan

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Publications (17)35.51 Total impact

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    ABSTRACT: InGaAsP/InGaP lasers emitting at 724–727 nm have been fabricated on GaAs substrates using liquid phase epitaxy. The threshold current is reduced to 8 kA/cm<sup>2</sup> by thinning the active layer. Room‐temperature cw operation is achieved for the first time in the lasing wavelength range below 760 nm in this quaternary system.
    Applied Physics Letters 07/1984; 44(11-44):1035 - 1037. DOI:10.1063/1.94628 · 3.52 Impact Factor
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    ABSTRACT: A rapidly degraded InGaAsP/InGaP double‐heterostructure laser (λ=810 nm) grown on a (001) oriented GaAs substrate during cw operation at room temperature, is investigated by photoluminescence topography and transmission electron microscopy. Several 〈100〉 dark‐line defects and 〈110〉 dark‐line defects parallel to the stripe are observed in the photoluminescence image of the active region. The 〈100〉 dark‐line defects are associated with classic interstitial type dislocation dipoles with Burgers vectors of the type a/2[101] 45° inclined to the junction plane. The 〈110〉 dark‐line defect corresponds to a half‐dislocation loop (b¯=a/2〈011〉) with many jogs (due to climb motion). In InGaAsP/InGaP material on GaAs, it is suggested that recombination enhanced defect motion (climb motion) can occur.
    Applied Physics Letters 06/1984; 44(9-44):861 - 863. DOI:10.1063/1.94958 · 3.52 Impact Factor
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    ABSTRACT: InGaAsP/InGaP double-heterostructure lasers emitting at 810 nm have been fabricated on GaAs substrates using liquid-phase epitaxy (LPE). A threshold current as low as 2.0 kA/cm2 with an external differential quantum efficiency of 54% is obtained. Thus it has been shown that high-quality InGaAsP/InGaP lasers can be obtained by LPE growth.
    Electronics Letters 02/1984; 20(9-20):374 - 375. DOI:10.1049/el:19840258 · 1.07 Impact Factor
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    ABSTRACT: InGaAsP/InGaP buried heterostructure lasers emitting at 810 nm have been grown on GaAs substrates using two-step liquid-phase epitaxy. A threshold current of 79 mA and an external differential quantum efficiency of 26&percnt; are obtained. Fundamental transverse mode operation up to 3 mW is achieved in the laser with the active region of 3.5 μm wide.
    Journal of Applied Physics 01/1984; 56:3086-3087. DOI:10.1063/1.333865 · 2.19 Impact Factor
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    ABSTRACT: Semicylindrical Zn-diffused stripe (SCD) GaAlAs lasers with a very narrow current-confining stripe and sufficient refractive-index step along the active layer are described. They have the lowest threshold current among this type of device previously reported. The devices having a 200 ¿m cavity length showed a CW threshold current of only 22 mA at 25°C and 45 mA at 105°C. Sufficient current confinement made it possible to operate at temperatures up to 165°C.
    Electronics Letters 02/1982; DOI:10.1049/el:19820580 · 1.07 Impact Factor
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    ABSTRACT: We investigated the dynamic characteristics related to the transient spectra of two types of transverse‐mode stabilized GaAlAs double‐heterostructure lasers: internally‐striped‐planar (ISP) and channeled‐substrate‐planar (CSP) lasers. These lasers exhibited a linear light‐current relation, stable transverse‐mode oscillation, and dynamic response with suppressed relaxation oscillations. Several differences in their spectral behavior have been observed. The dc spectrum of the CSP laser shows a single longitudinal mode, whereas the dc spectrum of the ISP laser shows multilongitudinal modes. In the ISP laser, the transient spectrum under fast pulse modulation is nearly identical to its dc spectrum. The CSP laser shows a transient spectrum that is broader than that in cw operation. The experimental results may be explained from the differences of their device structure and waveguiding mechanisms.
    Journal of Applied Physics 01/1981; DOI:10.1063/1.327588 · 2.19 Impact Factor
  • M. Yano, H. Nishi, M. Takusagawa
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    ABSTRACT: Temperature dependence of threshold current in InGaAsP/InP double‐heterostructure (DH) lasers was studied from the standpoint of the effect of carrier leakage from the quaternary active region into the InP confining layers. The carrier‐confinement coefficient, defined as the ratio of confined carriers to total injected carriers in the active region, was connected with other oscillation characteristics such as emission efficiency, carrier lifetime, and internal quantum efficiency in three different ways. These variations, as a function of ambient temperature, were measured and the temperature variation of the carrier‐confinement coefficient was evaluated and compared with that of threshold current. These results demonstrated that the carrier leakage was the dominant mechanism on temperature dependence of threshold current in InGaAsP/InP DH lasers. Moreover, we too discussed the other possibilities such as the effects of interfacial recombination at heterojunctions and laser parameters.
    Journal of Applied Physics 09/1980; DOI:10.1063/1.328226 · 2.19 Impact Factor
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    ABSTRACT: We examined the dependence of spontaneous carrier lifetime on the stripe width in internally striped-planar GaAlAs DH lasers by measuring the turn-on delay time of lasing emission under step current injection. The measured carrier lifetime reduces in narrow stripe lasers. Reasonable interpretation of the results can be given by the increased carrier density at threshold which results from the increasing waveguide loss and the carrier loss by out-diffusion in narrow stripe lasers. There is also given another explicit explanation on the reduced carrier lifetime by using the rate equation.
    IEEE Journal of Quantum Electronics 07/1980; DOI:10.1109/JQE.1980.1070544 · 2.11 Impact Factor
  • M. Yano, H. Nishi, M. Takusagawa
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    ABSTRACT: This paper presents the influences of interfacial recombination on the oscillation characteristics of InGaAsP/InP DH lasers. The effects of interfacial recombination at the two InP-InGaAsP interfaces, and a theoretical study of the oscillation characteristics such as threshold current density and differential quantum efficiency are discussed and compared with experimental results. The effects of interfacial recombination on the temperature dependence of threshold current are also examined.
    IEEE Journal of Quantum Electronics 07/1980; DOI:10.1109/JQE.1980.1070537 · 2.11 Impact Factor
  • M. Yano, H. Nishi, M. Takusagawa
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    ABSTRACT: This paper presents new stripe geometry InGaAsP/InP DH lasers having mechanisms for suppressing current spreads and for controlling the transverse mode parallel to the junction plane. The theoretical study for optimum design of these lasers from which the analytic method of oscillation characteristics, including control of the transverse mode parallel to the junction plane attributable to refractive index and gain, was derived is discussed. The oscillation characteristics, especially the waveguide properties of the transverse mode are reported. Experimental results show excellent agreement with the theory and show that the transverse mode is totally confined by the built-in passive waveguide for a stripe width of 5 μm.
    IEEE Journal of Quantum Electronics 01/1980; DOI:10.1109/JQE.1979.1069955 · 2.11 Impact Factor
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    ABSTRACT: Not Available
    IEEE Transactions on Electron Devices 12/1979; 26(11):1842- 1843. DOI:10.1109/T-ED.1979.19741 · 2.36 Impact Factor
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    ABSTRACT: Self‐aligned structure InGaAsP/InP DH lasers with emission wavelengths near 1.3 μm are studied. A cw threshold of about 100 mA is obtained in these lasers with cavity lengths of about 300 μm at a heat sink temperature of 25 °C. Light output increases linearly with current for outputs of 10 mW per facet and no kinks appear. Fundamental‐transverse and single‐longitudinal mode oscillation, and stable operation of fundamental‐transverse mode against injection current, are achieved. A cw operation up to 72 °C is obtained with a laser.
    Applied Physics Letters 09/1979; DOI:10.1063/1.91081 · 3.52 Impact Factor
  • M. Yano, H. Nishi, M. Takusagawa
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    ABSTRACT: Threshold characteristics of stripe-geometry InGaAsP/InP double-heterostructure injection lasers have been analytically derived as a function of active layer thickness and stripe width. The effects of stripe width, refractive index in the active layer, diffusion of injected carriers, carrier lifetime, absorption loss in the cladding layer, gain coefficient, and cavity length on the optimum thickness of the active layer which gives minimum threshold or on threshold current density were studied. These lasers were fabricated on
    IEEE Journal of Quantum Electronics 08/1979; DOI:10.1109/JQE.1979.1070063 · 2.11 Impact Factor
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    ABSTRACT: The paper examines the dynamic characteristics of GaAs/GaAlAs double-heterostructure lasers, which have an internally striped planar (ISP) structure using sulfur diffusion, under varying stripe-width conditions. It is shown that significant improvement is achieved in frequency response, pulse response and spectral behavior by narrowing the stripe width to the 5 to 7 micron range of ISP lasers with an undoped active region and a cavity length of about 150 microns. This improvement make these lasers suitable for high bit rate and long-distance optical fiber transmission. Results of life test of narrow stripe-geometry ISP lasers reveal that these lasers have a stable operation after more than 1000 hr at 70 C under 3-mW light output.
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    ABSTRACT: We measured frequency response of small signal intensity modulation of GaAs-AlGaAs DH lasers. Besides the anticipated resonant-like peaks, another resonant peak was observed in some diodes near the second harmonic frequency.
    Proceedings of the IEEE 10/1977; 65(9):1413- 1414. DOI:10.1109/PROC.1977.10732 · 5.47 Impact Factor
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    ABSTRACT: A new type of internally striped planar (ISP) DH lasers is developed with using a new Sulfur selective diffusion technique. The increase of the threshold ratio with the narrowing of the stripe width is more gentle for stripe width range near 10 µm in the laser than in both Zn-diffused planar and proton-bombardment stripe-geometry lasers. Single transverse mode operation with nearly constant width is confirmed up to 100 °C and up to three times of a threshold. Room-temperature CW lasers stably operate over more than 3000 hours. Any deterioration of laser characteristics caused by S atom and its diffusion process is not observed. Sulfur selective diffusion is one of most promising technique for long life lasers and other devices.
    Electron Devices Meeting, 1975 International; 02/1975