Takahide Sakamoto

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We theoretically prove that a conventional Mach-Zehnder modulator can generate an optical frequency comb with excellent spectral flatness. The modulator is asymmetrically dual driven by large amplitude sinusoidal signals with different amplitudes. The driving condition to obtain spectral flatness is analytically derived and optimized, yielding a simple(More)
We investigated an integrated optical modulator consisting of two Mach-Zehnder interferometers. The modulator can generate optical signals in various types of modulation formats, which have advantages for long-haul transmission, optical labeling, etc. By using a fabricated versatile optical modulator having traveling-wave electrodes designed for high-speed(More)
The generation of a 40-Gb/s 16-QAM radio-over-fiber (RoF) signal and its demodulation of the wireless signal transmitted over free space of 30 mm in W-band (75-110 GHz) is demonstrated. The 16-QAM signal is generated by a coherent polarization synthesis method using a dual-polarization QPSK modulator. A combination of the simple RoF generation and the(More)
We propose an optical initial phase control technique for external modulation in the format of minimum-shift keying (MSK). In this scheme, the optical phase discontinuities inherent to external frequencyshift- keying (FSK) modulation are compensated by use of an initial phase controller in conjunction with a FSK modulator. We present the principle of the(More)
-We described a novel optical label swapping (OLS) technique for optical packet systems using frequency-shift-keying (FSK) optical labeling. High-speed optical FSK signal can be generated by using an external FSK modulator consisting of four optical phase modulators. The FSK modulator was based on optical singlesideband (SSB) modulation technique, and(More)
This paper describes optical frequency comb generation using optical single-sideband modulation technique. We can obtain optical frequency shift using the singnal-sideband modulator consisting of four optical phase modulators, where the frequency shift is precisely equal to that of an rf-signal fed to the modulator. A series of optical spectral components(More)
Optical frequency comb generation by using a novel optoelectronic oscillator (OEO) is proposed and demonstrated with the emphasis placed on self-oscillating operation. In the OEO, a wideband LiNbO3 phase modulator is driven with a large-amplitude radio-frequency (RF) feedback signal to generate a deeply phase-modulated light wave; accordingly, an optical(More)