Kensuke Matsui

Tokyo Institute of Technology, Edo, Tōkyō, Japan

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Publications (6)3.17 Total impact

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    ABSTRACT: A 1.5 μm wavelength distributed reflector laser, consisting of a distributed Bragg reflector rear facet and a distributed feedback region, was realised using deep-etching technology. A low threshold current of I<sub>th</sub>=12.4 mA and a high differential quantum efficiency of η<sub>d</sub>=42% from the front facet was achieved with a submode suppression ratio of 33 dB (I=2.4 I<sub>th</sub>) for a fifth-order grating, 220 μm long and 6 μm wide device at room temperature
    Electronics Letters 07/2001; · 1.04 Impact Factor
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    ABSTRACT: A new type of distributed-reflector (DR) laser with a vertically aligned grating (VG) is proposed and was fabricated using CH<sub>4</sub>/H<sub>2</sub> reactive ion etching (RIE) without any regrowth. On the rear facet, a 15-element semiconductor/benzocyclobutene (BCB) distributed Bragg reflector (DBR) was used to increase the output efficiency and to decrease the threshold current. The threshold current was as low as 12 mA and the differential quantum efficiency as high as 42% from the front cleaved facet under room temperature operation for 220-μm-long cavity and 6-μm-wide stripe devices. GaInAsP VG-DR lasers with a fifth order grating (Λ=1200 nm) showed quasi single-mode operation with an SMSR of 35 dB
    Indium Phosphide and Related Materials, 2001. IPRM. IEEE International Conference On; 02/2001
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    ABSTRACT: 1.55 μm wavelength distributed feedback (DFB) lasers consisting of a first order vertical grating formed on the sidewalls of the high-mesa stripe geometry were realized by a simple electron beam lithography and CH<sub>4</sub>/H<sub>2</sub>-RIE etching. The threshold current of 15 mA and the differential quantum efficiency of 55% were obtained for a 370 μm long and 3.5 μm wide stripe device.
    Lasers and Electro-Optics, 2001. CLEO/Pacific Rim 2001. The 4th Pacific Rim Conference on; 02/2001
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    ABSTRACT: Single-mode GaInAsP lasers at a wavelength of 1.5 mum, fabricated using deep dry-etching technology are presented. In the novel design, the high reflectivity of a fifteen-element distributed Bragg reflector (DBR) is combined with the spectral selectivity of multiple cavities (MC) to achieve single-mode operation with high output efficiency. The etched structure was buried with polymer benzocyclobutene (BCB) in order to reduce the diffraction loss between coupled cavities, to passivate the sidewalls of the waveguide and to protect the structure from damage due to process handling. MC lasers with different numbers of cavities were analyzed by the transfer matrix method (TMM) including groove losses and the results of analysis are compared with experimental results of fabricated devices. For a coupled cavity (CC) laser, which has only two cavities, a threshold current of 11 mA and a submode suppression ratio (SMSR) of 36 dB at a bias current of 1.8 times the threshold were obtained for 5-mum-wide mesa stripe geometry.
    Japanese Journal of Applied Physics 01/2001; 40:4031-4037. · 1.07 Impact Factor
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    ABSTRACT: 1.5-mum-wavelength distributed feedback lasers with a deeply etched first order vertical grating were realized for the first time. It was shown that we can obtain an effective coupling by reducing the stripe width. The sample with the cavity length of 430 mum, 1.8 mum stripe width and 0.2 mum grating depth on each lateral side exhibited a 12.5 mA threshold current, 37% total differential quantum efficiency and 35 dB submode suppression ratio at a bias current of two times the threshold.
    Japanese Journal of Applied Physics 01/2001; 40. · 1.07 Impact Factor
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    ABSTRACT: 1.55 μm wavelength GaInAsP lasers with high reflective deeply etched semiconductor/benzocyclobutene (BCB) DBR showing low threshold current and high differential quantum efficiency were successfully obtained with high uniformity. Threshold current as low as 7.2 mA and differential quantum efficiency as high as 50% from the front cleaved facet were obtained with 160 μm-long DBR lasers with 15-DBR reflectors on the rear side. The reflectivity was estimated to be as high as 95% from the measurement of the threshold current dependence on the cavity length. Finally, a preliminary aging test under a room temperature CW condition showed stable operation for duration in excess of 300 hours
    Indium Phosphide and Related Materials, 2000. Conference Proceedings. 2000 International Conference on; 02/2000