Coupled-resonator-induced transparency (CRIT) effect has been widely studied in parallelly coupled double microring
resonators (MRRs), and various applications based on the CRIT effect have been demonstrated. We report the proposal
and demonstration of a directed logic circuit with the functions of XOR and XNOR using CRIT. Two electrical signals
applied to two coupled MRRs represent two operands of the logic operations, and the operation results are represented
by the output optical signal. As proof-of-concept, the thermo-optic modulation scheme is employed with an operating
speed of 10 kbps.
Electro-optic logic is a paradigm which employs the optical switch network to perform the logical operation. The status
of each switch in the optical network is determined by an electrical Boolean signal applied to it. The operation of each
switch is independent of the operations of other switches in the network and the operation result propagates in the
network at the speed of light. The overall latency of the logic circuit is very small and all switches perform their
operations almost simultaneously. Therefore, the electro-optic logic has a very high operation speed. Silicon microring
resonator is an attractive structure owing to its outstanding performances, such as compact size, ultra-low power
consumption and CMOS-compatible process. Therefore, the electro-optic logic based on silicon microring switches is
easy to realize large-scale integration and low-cost manufacture in a high-volume CMOS-photonics foundry. We have
proposed and demonstrated two electro-optic logic circuits based on silicon microring switches including XOR/XNOR
and AND/NAND. We also proposed the architectures to achieve encoder, decoder and half-adder, and demonstrated
them with the thermo-optic effect. In this paper, we will review the recent research on electro-optic logic circuits based
on silicon microring switches and introduce new development in this topic.
We report an eight-channel reconfigurable optical add-drop multiplexers (ROADMs) based on cascaded microring resonators with low power-consumption and compact footprint. Microheaters are fabricated on top of the microring resonators, which can be modulated through the thermo-optic effect to achieve the reconfigurability of the device. We
demonstrate the reconfigurable add-drop multiplexing functionality with the channel spacings of 100GHz and 50GHz,
with the channel centre wavelengths aligned to the International Telecommunication Unit (ITU) grid. The crosstalks for the two channel spacings are less than -22.5dB and -15.5dB, respectively. The tuning efficiency is about 4.854 mw/nm
and the tuning speed is about 12.4 kHz.
KEYWORDS: Waveguides, Channel projecting optics, Eye, Network on a chip, Microrings, Resonators, Silicon, Signal attenuation, Chemical mechanical planarization, Optoelectronics
We experimentally demonstrated four- and five-port non-blocking optical routers for photonic networks-on-chip. The
optical routers are based on cascaded microring resonators. New topology design reduces the number of microring
resonators and crossings, improving the performances in terms of tuning power consumption, optical loss, crosstalk
and channel uniformity of the optical routers. The efficient footprints are 300x340 μm2 and 440x660 μm2 for fourand
five-port optical routers, respectively. Static spectrum tests show that the 3-dB bandwidths are larger than 0.12
nm and 0.31 nm, the extinction ratios are larger than 13 dB and 20 dB for through ports, 30 dB and 16 dB for drop
ports, for four- and five-port optical routers, respectively. Moreover, routing functionality and signal integrity are
verified by 12.5 Gbps high-speed signal transmission experiments using the NRZ 231-1 PRBS pattern.
As a result of the low modulation efficiency of carrier-depletion Mach-Zehnder silicon optical modulator, it always
needs a high voltage around 6 V, which is very difficult to supply in an integrated high-speed CMOS chip. We
demonstrate a carrier-depletion Mach-Zehnder silicon optical modulator which works at a low voltage. Its coplanar
waveguide electrode is carefully designed to make sure the electrical wave loss along the device is low. The device
operates well at a data rate of 12.5 Gb/s, whose phase-shifter length is 2 mm. Voltages with the swinging amplitudes
being 1 V and 2 V are applied to the device with the reverse bias voltages of 0.5 V and 0.8 V. The extinction ratios are
7.67 and 12.79 dB respectively.
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