Author Search Result

[Author] Masatoshi SARUWATARI(9hit)

1-9hit
  • All-Optical Chirping Manipulation of Laser-Diode Chirped Optical Pulses Utilizing Cross-Phase Modulation in Optical Fibers

    Toshio MORIOKA  Masatoshi SARUWATARI  

     
    PAPER-Optical Communication Systems and Applications

      Vol:
    E73-E No:1
      Page(s):
    34-40

    A novel method for manipulating chirping characteristics of ultrashort optical pulses is proposed that utilizes cross-phase modulation induced in optical fibers by an intense pump pulse. To examine the effect of cross-phase modulation in optical fibers, blue-shift chirping profiles of CW 1.3 µm light from a distributed-feedback laser-diode (DFB-LD) induced by an intense pump pulse from a 1.3 µm mode-locked YAG laser are observed using time-resolved spectroscopy. The ratio of the two corresponding nonlinear indices (n2 XPM/n2 SPM) is found to be 1.8 from the obtained chirping profiles of the pump and signal, which is in good agreement with the theoretical value of 2. All-optical chirping manipulation of a 40 ps red-shift optical pulse from a gain-switched DFB-LD at 1.3 µm is successfully demonstrated for the first time to our knowledge by compensating for the original signal chirp utilizing cross-phase modulation by a 110 ps intense pump pulse. This method provides a new all-optical approach to controlling the phase or chirping characteristics of optical signals and provides a convenient and flexible way of generating ultrashort pulses with desired chirping characteristics and time durations.

  • Polarization-Independent Wavelength Conversion Using Four-Wave Mixing in Single-Mode Fibers Pumped with Cross-Polarized High Frequency Pulses

    Kenichiro TSUJI  Hideaki YOKOTA  Masatoshi SARUWATARI  

     
    PAPER-Optical Systems and Technologies

      Vol:
    E84-C No:5
      Page(s):
    564-570

    This paper describes a simple polarization-independent wavelength conversion method using degenerated four-wave mixing (FWM) in single-mode fibers pumped with cross-polarized high frequency, saw-tooth pulses from a single pump source. Successful polarization-independent wavelength conversion is experimentally confirmed with less than 12% and 5.6% variation using a gain-switched LD pumping and a mode-locked fiber laser pumping, respectively. We clarify that the interference effect between two orthogonal pump pulses must be taken into account to achieve a good polarization-insensitive operation, since even the small pulse edges bring about the large polarization fluctuations when they are interfered. Furthermore, it is reveal that the shorter pump pulse broadens its own spectrum due to the self-phase modulation in fibers, resulting in poor FWM efficiency. Finally, possibility of high-speed operation is discussed taking into account the pump pulse conditions.

  • Polarization-Independent Wavelength Conversion Using Four-Wave Mixing in Single-Mode Fibers Pumped with Cross-Polarized High Frequency Pulses

    Kenichiro TSUJI  Hideaki YOKOTA  Masatoshi SARUWATARI  

     
    PAPER-Optical Systems and Technologies

      Vol:
    E84-B No:5
      Page(s):
    1190-1196

    This paper describes a simple polarization-independent wavelength conversion method using degenerated four-wave mixing (FWM) in single-mode fibers pumped with cross-polarized high frequency, saw-tooth pulses from a single pump source. Successful polarization-independent wavelength conversion is experimentally confirmed with less than 12% and 5.6% variation using a gain-switched LD pumping and a mode-locked fiber laser pumping, respectively. We clarify that the interference effect between two orthogonal pump pulses must be taken into account to achieve a good polarization-insensitive operation, since even the small pulse edges bring about the large polarization fluctuations when they are interfered. Furthermore, it is reveal that the shorter pump pulse broadens its own spectrum due to the self-phase modulation in fibers, resulting in poor FWM efficiency. Finally, possibility of high-speed operation is discussed taking into account the pump pulse conditions.

  • Highly Stable, Actively Mode-Locked Er-Doped Fiber Laser Utilizing Relaxation Oscillation as Detuning Monitor

    Hidehiko TAKARA  Satoki KAWANISHI  Masatoshi SARUWATARI  

     
    PAPER

      Vol:
    E81-C No:2
      Page(s):
    213-220

    We investigate the relaxation oscillation characteristics of an actively mode-locked fiber laser and a novel stabilizing method of the laser theoretically and experimentally. The stabilizing method controls cavity length to suppress the rf power of the relaxation oscillation frequency of the laser output, and can directly monitor the stability of the laser to ensure the most stable operation. With this method, the rf power ratio between mode-locking frequency and the background noise can be kept to more than 70 dB, and highly stable transform-limited pulse generation is achieved. Bit-error-free operation at 6. 3 GHz over 10 hours is successfully demonstrated. The stability of the center wavelength of the laser output and the required accuracy of cavity control for high-speed laser operation are also discussed.

  • Reduction of Timing Jitter Due to Gordon-Haus Effect in Ultra-Long High Speed Optical Soliton Transmission Using Optical Bandpass Filters

    Shingo KAWAI  Katsumi IWATSUKI  Ken-ichi SUZUKI  Shigendo NISHI  Masatoshi SARUWATARI  

     
    PAPER

      Vol:
    E77-B No:4
      Page(s):
    462-468

    The timing jitter reductions with differently shaped optical bandpass filters are discussed and the transmission distance achievable against the timing jitter is evaluated using optical bandpass filters in several tens of Gb/s soliton transmission. Experimental confirmation of timing jitter reduction with optical bandpass filters is demonstrated in 10Gb/s optical soliton recirculating loop experiments by measuring the timing jitter and the bit error rates.

  • 100Gbit/s Transmission Using All Optical Circuits

    Satoki KAWANISHI  Masatoshi SARUWATARI  

     
    INVITED PAPER

      Vol:
    E77-B No:4
      Page(s):
    441-448

    Recent progress on the ultrahigh-speed optical transmission experiments are reviewed including the ultrashort pulse generation, high-speed timing extraction, all-optical multi/demultiplexing. Also discussed are the latest 100 Gbit/s experiments and a scope to higher bit-rate, longer distance optical transmission.

  • Analysis of XGM-Based Wavelength-Conversion Using ASE in SOAs

    Kenichiro TSUJI  Naoyuki MATSUSHITA  Noriaki ONODERA  Masatoshi SARUWATARI  

     
    PAPER

      Vol:
    E86-C No:5
      Page(s):
    741-748

    Wavelength conversion using the cross-gain modulation (XGM) of amplified spontaneous emission (ASE) in a traveling-wave type semiconductor optical amplifier (TW-SOA) is theoretically studied. Taking into account the spatial and temporal variations of carrier density along the SOA length, output signal and converted ASE waveforms are analyzed. We also reveal the dependency of the signal and converted ASE waveforms on input signal power and repetition frequency, and confirm that numerical analyses well agree with the experimental results. Finally we qualitatively clarify the way to improve frequency response by simulating eye-diagrams for long SOAs and assist light pumping for the first time.

  • Theoretical Study of Assist Light Effect on XGM and XPM-Based Wavelength-Conversion Using SOAs

    Kenichiro TSUJI  Takuya WATANABE  Noriaki ONODERA  Masatoshi SARUWATARI  

     
    PAPER-Optical Active Devices and Modules

      Vol:
    E88-C No:5
      Page(s):
    973-980

    For wavelength conversion based on cross-gain modulation (XGM) and cross-phase modulation (XPM) in semiconductor optical amplifiers (SOAs), a CW assist light is quite effective for acceleration of carrier recovery and reduction of pattern effects. We theoretically study assist light conditions both for XGM- and XPM-based wavelength conversion by numerically simulating eye-diagrams. Taking into account the spatial and temporal variations of carrier density along the SOA length, we successfully clarify the dependences of wavelength, power, and propagation direction of the assist light, and reveal the principal difference of response characteristics between XGM and XPM depending on carrier modulation.

  • High-Speed Optical Signal Processing for Communications Systems

    Masatoshi SARUWATARI  

     
    INVITED PAPER

      Vol:
    E78-B No:5
      Page(s):
    635-643

    This paper reviews very high-speed optical signal processing technology based on the instantaneous characteristic of optical nonlinearities. Focus is placed on 100-Gbit/s optical time-division multiplexing (TDM) transmission systems. The key technologies including ultrashort optical pulse generation, all-optical multiplexing/demultiplexing and optical timing extraction techniques are alse described together with their major issues and future prospects.

FlyerIEICE has prepared a flyer regarding multilingual services. Please use the one in your native language.