We report on four-wave mixing in coupled photonic crystal nano-cavities on a silicon-on-insulator platform. Three photonic wire cavities are side-coupled to obtain three modes equally separated in energy. The structure is designed to be self-filtering, and we show that the pump is rejected by almost two orders of magnitude. We study both the stimulated and the spontaneous four-wave mixing processes: owing to the small modal volume, we find that signal and idler photons are generated with a hundred-fold increase in efficiency as compared to silicon micro-ring resonators.

This paper reports the performances of a silicon photonics optical switch matrix fabricated by using large scale 3D integration. The wavelength selective optical switch consists of a photonic integrated circuit (PIC), with 1398 circuit elements, interconnected in a 3D stack with its control electronic integrated circuit (EIC). Each PIC element can be trimmed or reconfigured by using metallic heaters. The EIC is designed to drive the heaters and to read the signal of monitor photodiodes integrated into the PIC. Small footprint and high energy efficiency are achieved in the PIC and the EIC. Automatic wavelength alignment of the optical circuits in the PIC to the ITU grid and fine temperature tuning of each photonic element to optimize the switch insertion losses are obtained by an optimization routine. A fully packaged switch with input/output fibers is tested both for optical and electrical characteristics as well as for the system performances. Fiber to fiber insertion losses of about 20 dB and channel isolation of -35 dB are achieved. BER characteristics at 25 Gbps are evaluated. Perspective applications of the optical switch in optical transport and intra-data center networks are discussed.

We report on an experimental prototype of a low-cost silicon photonic reconfigurable optical add/drop multiplexer (ROADM). The device is able to operate with up to 12 wavelength division multiplexing channels. In order to control the polarization of the multi-wavelength signal at the input of the device, an integrated polarization controller is investigated as an alternative to the polarization diversity device architecture. The integrated ROADM is equipped with optical switches for the selection of the path direction and variable optical attenuators for optical power control. We demonstrate the polarization insensitive routing of 10 Gb/s channels between two ROADM nodes with error-free transmission.

On-chip optical communications require high-performance, energy-efficient, and scalable multiplexing techniques for enabling high parallelism. Mode division multiplexing (MDM) is gaining momentum, but its scalability is limited by the crosstalk and the (de)multiplexing complexity. To overcome such limitations, this paper proposes the exploitation of super-modes in closely spaced arrays of waveguides. A theoretical approach demonstrates the generation of super-modes achieved by perturbing the uniformity of waveguide arrays. Spectral characterization shows a crosstalk of about $-20\mathrm{dB}$ on the C band, in a nonuniform array of five silicon-on-isolator waveguides.