Extensive mobile data communications produce burst of data traffic in information and communication networks. The data from the wireless terminals are transmitted through optical-fibre networks, and therefore, there are growing demands on performance enhancement in optical-fibre communication networks with respect to transmission speed and capacity. With the advent of high-speed photonic devices, data transmission beyond 100 Gbit/s has been achieved in the cutting-edge optical-fibre communication networks.
Photonic integrated circuits based on silicon photonics, which are fabricated on large-diameter silicon wafers by CMOS-based processes, are crucial for small-footprint optical components with low fabrication costs, and thus allow expansion of the high-speed optical-fibre networks over the globe. Integrated silicon Mach-Zehnder optical modulators are technology drivers for high-speed optical-fibre communications since they play significant roles in high-quality optical signal generation in diverse modulation formats without signal distortion such as frequency chirping.
Here, high-speed integrated silicon Mach-Zehnder optical modulators are reviewed in the light of science and technology for highly functional photonic integrated devices in the advanced optical-fibre communications. In particular, silicon Mach-Zehnder optical modulators operating on the physical principle of free-carrier plasma dispersion are the highlight of the review subjects in terms of high-speed operation with capabilities of small-footprint photonic integration and low power consumption. Optical modulation with bit rates of 100 Gbit/s and beyond has been realised using the silicon Mach-Zehnder optical modulators, which accommodate silicon-waveguide phase shifters having PN or PIN junctions. Device physics and performances of a variety of silicon-waveguide phase shifters are elaborated. Travelling-wave electrodes propagate microwave signals to the junctions in the phase shifters. Modelling and simulation based on physical profiles of carrier distribution in the junctions and lumped-element equivalent circuits for the travelling-wave electrodes are presented for performance analysis of the phase shifters and the travelling-wave electrodes. In the high-speed optical-fibre communications, polarisation-division multiplexing is exploited to data multiplexing. Monolithically integrated silicon Mach-Zehnder optical modulators for polarisation-division multiplexing are described in the aspects of device physics, fabrication and performance characterisation. Long-haul optical-fibre transmission and short-reach photonic networking using high-speed integrated silicon Mach-Zehnder modulators are presented for applications of the photonic integrated devices.
Extensive mobile data communications produce burst of data traffic in information and communication networks. The data from the wireless terminals are transmitted through optical-fibre networks, and therefore, there are growing demands on performance enhancement in optical-fibre communication networks with respect to transmission speed and capacity. With the advent of high-speed photonic devices, data transmission beyond 100 Gbit/s has been achieved in the cutting-edge optical-fibre communication networks.
Photonic integrated circuits based on silicon photonics, which are fabricated on large-diameter silicon wafers by CMOS-based processes, are crucial for small-footprint optical components with low fabrication costs, and thus allow expansion of the high-speed optical-fibre networks over the globe. Integrated silicon Mach-Zehnder optical modulators are technology drivers for high-speed optical-fibre communications since they play significant roles in high-quality optical signal generation in diverse modulation formats without signal distortion such as frequency chirping.
Here, high-speed integrated silicon Mach-Zehnder optical modulators are reviewed in the light of science and technology for highly functional photonic integrated devices in the advanced optical-fibre communications. In particular, silicon Mach-Zehnder optical modulators operating on the physical principle of free-carrier plasma dispersion are the highlight of the review subjects in terms of high-speed operation with capabilities of small-footprint photonic integration and low power consumption. Optical modulation with bit rates of 100 Gbit/s and beyond has been realised using the silicon Mach-Zehnder optical modulators, which accommodate silicon-waveguide phase shifters having PN or PIN junctions. Device physics and performances of a variety of silicon-waveguide phase shifters are elaborated. Travelling-wave electrodes propagate microwave signals to the junctions in the phase shifters. Modelling and simulation based on physical profiles of carrier distribution in the junctions and lumped-element equivalent circuits for the travelling-wave electrodes are presented for performance analysis of the phase shifters and the travelling-wave electrodes. In the high-speed optical-fibre communications, polarisation-division multiplexing is exploited to data multiplexing. Monolithically integrated silicon Mach-Zehnder optical modulators for polarisation-division multiplexing are described in the aspects of device physics, fabrication and performance characterisation. Long-haul optical-fibre transmission and short-reach photonic networking using high-speed integrated silicon Mach-Zehnder modulators are presented for applications of the photonic integrated devices.