The Review of Laser Engineering
Online ISSN : 1349-6603
Print ISSN : 0387-0200
ISSN-L : 0387-0200
Volume 17, Issue 9
Displaying 1-8 of 8 articles from this issue
  • Kenzo MIYAZAKI
    1989 Volume 17 Issue 9 Pages 614-615
    Published: September 28, 1989
    Released on J-STAGE: March 17, 2010
    JOURNAL FREE ACCESS
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  • Noboru EDAGAWA, Kiyofumi MOCHIZUKI
    1989 Volume 17 Issue 9 Pages 616-627
    Published: September 28, 1989
    Released on J-STAGE: March 17, 2010
    JOURNAL FREE ACCESS
    Amplification characteristics of fiber Raman amplifiers are reviewed. Simultaneous Raman amplification experiments of wavelength-division multiplexed (WDM) optical signals and a Raman amplification experiment of coherent optical signals using a 1.46 μm high-power semiconductor laser pump light source and an 80km high-Raman-gain optical fiber are described. Simultaneous amplification of WDM optical signals was demonstrated using 1.2Gbt/s and 565Mbit/s, intensity-modulated optical signals in unidirectional and bidirectional configurations with optical gains of 7dB and 6dB, respectively. No significant degradation was observed in any configuration. Raman amplification of coherent optical signals was also demonstrated through a 560Mbit/s FSK optical heterodyne transmission experiment. An optical gain of 7.5dB was obtained without any degradation. The results show that fiber Raman amplifiers can be used in WDM and coherent optical telecommunication systems.
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  • Koji YASUKAWA
    1989 Volume 17 Issue 9 Pages 628-634
    Published: September 28, 1989
    Released on J-STAGE: March 17, 2010
    JOURNAL FREE ACCESS
    The current state of research and development activities of optical intersatellite link (ISL) technologies in ATR Optical and Radio Communications Research Laboratories is introduced. Concerning modulation/demodulation techniques, the development of a high power, high speed optical modem is described. Optical beam control techniques under the solar conjunction are also introduced. Subjects for further research on coherent detection etc. are summarized. An optical space communication experiment program in USA, Europe, and Japan is outlined.
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  • Minoru DOSHIDA, Hiroshi HARA
    1989 Volume 17 Issue 9 Pages 635-641
    Published: September 28, 1989
    Released on J-STAGE: March 17, 2010
    JOURNAL FREE ACCESS
    The operational properties of a N2/CO2 subsonic mixing laser are described. A small signal gain of 1.8m-1, a saturation intensity of 100W/cm2 and a specific power of 9.5J/g were obtained under the optimum conditions. Comparison of the results with those of a N2/CO2 supersonic mixing laser indicates that a N2/CO2 subsonic mixing laser is scalable in size and power more easily than the N2/CO2 supersonic mixing laser.
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  • Polymerization and Curing Properties in Argon Ion Laser Irradiation
    Kaoru SUZUKI, Shigeyuki MASUTANI, Tetsuya TANIYAMA, Junji NAKATA, Taka ...
    1989 Volume 17 Issue 9 Pages 642-651
    Published: September 28, 1989
    Released on J-STAGE: March 17, 2010
    JOURNAL FREE ACCESS
    Light-activated dental composite resins undergo polymerization and curing by free-radical initiation like auto-cured resins. We studied the polymerization and curing properties of some commercially available light activated composites by using argon-ion laser.
    Results are summarized as: (1) The volume of a cured resion is dependent on the wavelength, and the maximum volume is obtained at 466 and 477 nm; (2) The volume of the cured resin increases with increasing irradiation power and time; (3) The rate of polymerization shrinkage gradually increases, before the saturation and (4) A correlation was observed between light transmittance and polymerization shrinkage for the composites of hybrid and traditional types which are relatively highly filled, but not for MFR type resins containing less micro-filler.
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  • Hajime NISHIOKA, Hideaki KURANISHI, Kenichi UEDA, Hiroshi TAKUMA
    1989 Volume 17 Issue 9 Pages 652-661
    Published: September 28, 1989
    Released on J-STAGE: March 17, 2010
    JOURNAL FREE ACCESS
    A derivative of the linear tri-cyclic compound acridine in several different solvents is shown to be as an effective saturable absorber for short pulse KrF lasers. Acridine dissolved in ethanol showed the best bleaching characteristics for a 20 ps laser pulse, the ratio of primary to the excited absorption cross-section of 7.3:1 and the low saturation fluence of 1.1mJ/cm2 due to the large absorption cross-section of 5.6 × 10-16cm2 at 249nm. Temporal behavior of the absorption recovery showed two time constants of 0.4ns and 115ns, the fast component corresponded to the measured fluorescence decay time of 0.43ns for the first excited singlet state. The ASE free operation (less than 0.1% of the laser energy) and the pulse compression in a saturated amplifier have been demonstrated. The laser pulse width was compressed by a factor of 4 in an absorber-amplifier arrangement.
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  • Dong Hwan KIM, Sang Soo LEE
    1989 Volume 17 Issue 9 Pages 662-671
    Published: September 28, 1989
    Released on J-STAGE: March 17, 2010
    JOURNAL FREE ACCESS
    Iodine photodissociation laser pulse (λ=1.32μm, pulse width=13.3ns) is focussed to various targets (C, Al, Ti, Fe, Cu, Mo) and laser plasma is produced. Two electron temperatures are obtained from the two slopes of continuous x-ray spectra over the region (0<μ<19.84A). Zdependence of two electron temperatures (6≤Z≤42) are discussed from the characteristics of the plasma heating processes to which the long pulse laser beam is involved. One dimensional hydrodynamic model for the plasma electrons is used and the time-averaged temperature is derived theoretically to explain the cold electron temperature Tc obtained experimentally. Also, the hot electron temperature Th obtained experimentally is explained by the effect of parametric instability.
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  • 1989 Volume 17 Issue 9 Pages plate1
    Published: September 28, 1989
    Released on J-STAGE: March 17, 2010
    JOURNAL FREE ACCESS
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