title: Slow-light Mach-Zehnder modulators based on Si photonic crystals.
abstract: Mach-Zehnder optical modulators are the key devices for high-speed electrical-to-optical conversion in Si photonics. Si rib waveguides with a p-n diode structure operated in the carrier depletion mode have mainly been developed as their phase shifters. Their length is usually longer than millimeters due to the limited change in the refractive index due to the carrier depletion in a Si p-n diode. This length is shorter than commercial LiNbO3modulators, but still much shorter devices are desired for large-scale integration and for simplifying the high-speed RF modulation. A promising solution is to use slow light in photonic crystal waveguides, which enhances the modulation efficiency in proportion to the group-velocity refractive indexng. In particular, dispersion-engineered slow light allows more than five-fold enhancement, maintaining a wide working spectrum as well as large temperature tolerance. The devices with a phase shifter length of around 100μm are fabricated by a standard process compatible with complementary metal-oxide semiconductors. The operation at 10 Gbps and higher speeds are obtained in the wavelength range of 16.9 nm and temperature range of 105 K.
authors.affiliation: Department of Electrical and Computer Engineering Yokohama National University 79-5 Tokiwadai, Hodogayaku, Yokohama 240-8501, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Baba
authors.affiliation: Department of Electrical and Computer Engineering Yokohama National University 79-5 Tokiwadai, Hodogayaku, Yokohama 240-8501, Japan.
authors.forename: Hong C
authors.initials: HC
authors.lastname: Nguyen
authors.affiliation: Department of Electrical and Computer Engineering Yokohama National University 79-5 Tokiwadai, Hodogayaku, Yokohama 240-8501, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Yazawa
authors.affiliation: Department of Electrical and Computer Engineering Yokohama National University 79-5 Tokiwadai, Hodogayaku, Yokohama 240-8501, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Terada
authors.affiliation: Department of Electrical and Computer Engineering Yokohama National University 79-5 Tokiwadai, Hodogayaku, Yokohama 240-8501, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: Department of Electrical and Computer Engineering Yokohama National University 79-5 Tokiwadai, Hodogayaku, Yokohama 240-8501, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Watanabe
keywords: Mach–Zehnder; Optical modulator; Photonic crystal; Si photonics; Slow light