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Femtosecond Operation of a Polarization-Discriminating Symmetric Mach-Zehnder All-Optical Switch and Improvement in Its High-Repetition Operation
Shigeru NAKAMURA Yoshiyasu UENO Kazuhito TAJIMA
IEICE TRANSACTIONS on Communications
Publication Date: 1999/02/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Joint Special Issue on Photonics in Switching: Systems and Devices)
Category: Photonic Switching Devices
ultrafast, all-optical switch, optical demultiplexer, nonlinear optical effect, band-filling effect, interferometer, semiconductor waveguide,
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We experimentally demonstrate the ultrafast and high-repetition capabilities of a polarization-discriminating symmetric Mach-Zehnder (PD-SMZ) all-optical switch. This switch, as well as an original symmetric Mach-Zehnder (SMZ) all-optical switch, is based on a highly efficient but slowly relaxing band-filling effect that is resonantly excited in a passive InGaAsP bulk waveguide. By using a mechanism that cancels out the effect of the slow relaxation, ultrafast switching is attained. We achieve a switching time of 200 fs and demultiplexing of 1.5 Tbps, showing the applicability of the SMZ or PD-SMZ all-optical switches to optical demultiplexing of well over 1 Tbps for the first time. High-repetition capability, which is another important issue apart from the switching speed, is also verified by using control pulses at a repetition rate of 10.5 GHz. We also discuss the use of nonlinearity in a semiconductor optical amplifier to further reduce the control-pulse energy.