The Review of Laser Engineering
Online ISSN : 1349-6603
Print ISSN : 0387-0200
ISSN-L : 0387-0200
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Volume 26, Issue 7
Displaying 1-16 of 16 articles from this issue
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  • [title in Japanese]
    Yoshinobu AOYAGI
    1998 Volume 26 Issue 7 Pages 513
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.513
    JOURNAL FREE ACCESS
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  • Preface for Special Issue on “Terahertz Electromagnetic Radiation”
    Tetsuro KOBAYASHI
    1998 Volume 26 Issue 7 Pages 514
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.514
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  • Terahertz Electromagnetic Waves: Generation and Applications
    Kiyomi SAKAI, Masahiko TANI, Shuji MATSUURA
    1998 Volume 26 Issue 7 Pages 515-521
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.515
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    This paper describes the terahertz electromagnetic pulses emitted when femtosecond laser pulses irradiate quantum wells, bulk semiconductors, and photoconductive antennas fabricated on low-temperature-grown GaAs substrates. The continuous-wave (CW) terahertz electromagnetic radiation emitted when these photoconductive antennas are excited by two single-frequency CW semiconductor lasers is also described, as are the applications of the resultant terahertz wave in fields such as imaging and spectroscopy.
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  • Tunable Terahertz-Wave Generation by Parametric Oscillation and Its Application
    Kodo KAWASE, Hiromasa ITO
    1998 Volume 26 Issue 7 Pages 522-526
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.522
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    Widely tunable coherent terahertz (THz) wave generation was successfully demonstrated based on the laser light scattering from the lowest A1-symmetry polariton mode by using a Q-switched Nd: YAG laser pumping. This method exhibits multiple advantages like wide tunability (frequency: 0.9-2.2 THz), coherency and compactness of its system. In this paper, the general performances of this THz generator, and its applications are reported. A spectroscopic application is demonstrated by measuring the water vapor absorption. This THz-wave source is also applied to the differential imaging. In a proof-of-concept experiment, we optically tagged objects embedded in a shade and measured the difference between transmittance at two wavelengths.
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  • Enhanced Terahertz-Radiation from Semiconductors under Magnetic Field
    Hideyuki OHTAKE, Nobuhiko SARUKURA
    1998 Volume 26 Issue 7 Pages 527-530
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.527
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    We have generated enhanced Terahertz (THz) -radiation from semiconductors under magnetic field. The average power of THz-radiation, peaked at frequency of -0.3 THz, reaches 650 μW. We have studied the ellipticity of the THz radiation and have found that it depends strongly on magnetic field. In addition, we have demonstrated a new scheme for generating THz-radiation using a saturable Bragg reflector placed inside a mode-locked Ti: sapphire laser cavity. By using this scheme, THz-radiation with 0.8 μW has been observed.
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  • Terahertz Radiation from Ultrafast Photoconductive Switches
    Taro ITATANI, Tadashi NAKAGAWA
    1998 Volume 26 Issue 7 Pages 531-535
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.531
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    We describe fabrication of insulator-gap photoconductive switches forming by an atomic force microscope (AFM). The insulator-gap structure prevents discharge in a photoconductive gap, realizing strong electric field in photo-absorbing region. We made 43 nm, 100 nm and multi-gap photoconductive switches which generates strong THz signals. We have measured the transmission modes and the radiation modes. The transmission modes were measured by the electro-optic sampling which can measure the vector components of the electric field for the photoconductive switches with coplanar transmission lines. We have observed clearly the longitudinal components of electric field which can not be ignored in femtosecond region. The radiation modes from the switches with antenna structure were also measured by a Fourier transform polarizing interferometer. The radiation from the switch exceeds more than 1 THz and rather strong compared to the switch made by normal lift-off process.
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  • Terahertz Radiation from High-Temperature Superconductors
    Masanori HANGYO, Masayoshi TONOUCHI, Masahiko TANI, Kiyomi SAKAI
    1998 Volume 26 Issue 7 Pages 536-540
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.536
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    Ultrashort elctromagnetic pulses with time width of -0.5 ps are emitted from high temperature superconducting films by exciting with femtosecond laser pulses. The Fourier spectrum of them extends from 0.1 to 3 THz. The characteristics of the radiation are described in detail including various properties of the radiation related to magnetic fields. Various possible applications of this phenomenon are proposed and demonstrated. We propose a new field of “superconducting optoelectronics”, in which ultrafast optoelectronics and superconducting electronics are combined.
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  • Terahertz Wave p-type Ge Laser
    Norihisa HIROMOTO
    1998 Volume 26 Issue 7 Pages 541-545
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.541
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    The recent studies on the p-type Ge hot-hole laser oscillating in the terahertz wave region are described in this review. The present stage of development is now very close to the practical use as a tunable solid-state terahertz-wave source. Though only pulse oscillation has been realized due to heating so far, miniaturization of the p-Ge laser is advancing to obtain the continuous wave oscillation by decreasing the input power necessary for lasing. Lasing from a very small p-Ge laser of 1×1×5 mm3 in size has recently achieved with input peak power of only 300W.
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  • Scanning Near-Field Millimeter-Wave Microscope
    Tatsuo NOZOKIDO, Jongsuck BAE, Koji MIZUNO
    1998 Volume 26 Issue 7 Pages 546-550
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.546
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    A small aperture or antenna can confine electromagnetic radiation to dimensions far smaller than the wavelength. Scanning such a structure in close proximity to an object can yield microscopic images with correspondingly high resolution. The benefit of using microwaves and millimeter-waves in scanning near-field microscopy lies in the promise of new types of material contrast. A good example is the mapping of electronic transport properties. In this review an overview of scanning near-field microwave, millimeter-wave, and submillimeter-wave microscopy is presented, a millimeter-wave microscope system using a slit-type probe is described in detail, and the application of this microscope for the visualization of photo-excited free carriers in a silicon substrate is demonstrated.
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  • Visualization of the Beam Waist and Focusability of Intense Short-Pulse Terahertz Radiation
    Shinji IZUMIDA, Shingo ONO, Hideyuki OHTAKE, Zhenlin LIU, Nobuhiko SAR ...
    1998 Volume 26 Issue 7 Pages 551-553
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.551
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    We investigate the focusability of intense short-pulse THz radiation from InAs using the knife edge method. We find that the spatial distribution of this THz radiation intensity is Gaussian, and we can focus it down to approximately 2-mm in diameter. We also visualize the 3D THz-radiation intensity distribution around the focus point using a knife edge on automatic translation stages.
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  • Characterization of New Scheme of Amplitude Modulated Harmonically Mode-Locked Fiber Ring Lasers
    Rintaro NOMURA, Adi RAHWANTO, Norihiko NISHIZAWA, Toshio GOTO, Masakaz ...
    1998 Volume 26 Issue 7 Pages 554-558
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.554
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    A new simple scheme of the amplitude modulated harmonically mode-locked (AM-HML) Er-doped fiber ring laser is developed. The lasing characteristics are experimentally investigated, and a well-stabilized modelocked operation is confirmed. The AM-HML fiber ring laser generates nearly transform-limited sech pulse train.
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  • Measurement of Magnetic Parameters Based on the Static Balance of a Magnetically Suspended Pellet for Laser Fusion
    Hiroki YOSHIDA, Yukio SAKAGAMI
    1998 Volume 26 Issue 7 Pages 559-562
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.559
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    Uniform compression is one of the key issues of the laser fusion scheme. A nonsupported pellet has been desired not to degrade spherically symmetric implosion. A Magnetically Suspended Pellet (MSP) is possible to realize the pellet without any physical contact. To clarify characteristics of the electric current in the suspension magnet and the pellet position, we theoretically and experimentally analyzed the MSP system. We determined the essential parameters: the magnetic shape coefficient Km = 10 and the specific permeability μm=15.
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  • TiN film for Transparent Conductors Formed by Pulsed Laser Deposition in Reactive Gas
    Takaomi MATSUTANI, Hiroaki MATSUE, Kenji KUMAZAKI, Uichi KUBO, Takeyos ...
    1998 Volume 26 Issue 7 Pages 563-564
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.563
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    A titanium nitride film for a transparent conductor was formed on a SiO2 substrate at room temperature by using a pulsed laser deposition method. The ablation is promoted from a Ti target with KrF excimer laser irradiation in an N2 ambient gas. The structure of the film measured by using XRD was mainly TiN polycrystalline. In the case of the film thickness thinner than the wavelength of visible light, the transmittance and sheet resistance of the films were in the range of 74-47 % and 1000-70Ω/_??_, respectively.
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  • Influence of Laser Pulse Duration on N2+, N+, and N2+ Formation Processes in the Nitrogen Molecule
    AkramF. ISKANDEROV, TimurbekU. ARSLANBEKOV, Junkei KOU, Shuji SAKABE, ...
    1998 Volume 26 Issue 7 Pages 565-567
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.565
    JOURNAL FREE ACCESS
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    The molecular nitrogen ion, N2+, and singly and doubly charged atomic nitrogen N+, N2+ were formed by laser multiphoton ionization and detected in the time-of-flight (TOF) spectra. The excitation lasers were a Ti: sapphire femtosecond laser (up to 1.0×1016 W/cm2 in 100 fs at a wavelength of 790 nm) and a nanosecond laser (up to 1.2×1013 W/cm2 in 9 ns at 532 nm). The highest signal intensity among these ions resulted from N2+ in the major region of the laser fluence.
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  • Report on APLS'98 (The First Asian Pacific Laser Symposium)
    Masahiro NAKATSUKA, Hisanori FUJITA
    1998 Volume 26 Issue 7 Pages 568-569
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.568
    JOURNAL FREE ACCESS
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  • Fundamentals of Imaging Reflective Optics II: Ray Tracing
    Takeshi NAMIOKA
    1998 Volume 26 Issue 7 Pages 570-574
    Published: July 15, 1998
    Released on J-STAGE: August 25, 2010
    DOIhttps://doi.org/10.2184/lsj.26.570
    JOURNAL FREE ACCESS
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