This paper review our recent work on silicon modulators based on free carrier concentration, working in the O-band of optical communications (1260 nm - 1360 nm) for short distance applications. 25 Gbit/s OOK modulation is obtained using a driving voltage of 3.3 Vpp , and QPSK dual-drive Mach-Zehnder modulator (DDMZM) operating in the O-band is demonstrated for the first time.
Space division multiplexing (SDM) is currently widely investigated in order to provide enhanced capacity thanks to the utilization of space as a new degree of multiplexing freedom in both optical fiber communication and on-chip interconnects. Basic components allowing the processing of spatial modes are critical for SDM applications. Here we present such building blocks implemented on the silicon-on-insulator (SOI) platform. These include fabrication tolerant wideband (de)multiplexers, ultra-compact mode converters and (de)multiplexers designed by topology optimization, and mode filters using one-dimensional (1D) photonic crystal silicon waveguides. We furthermore use the fabricated devices to demonstrate on-chip point-to-point mode division multiplexing transmission, and all-optical signal processing by mode-selective wavelength conversion. Finally, we report an efficient silicon photonic integrated circuit mode (de)multiplexer for few-mode fibers (FMFs).
We report on direct numerical calculations and experimental measurements of the group-index dispersion in a photonic crystal waveguide fabricated in silicon-on-insulator material. The photonic crystal is defined by a triangular arrangement of holes and the waveguide is carved out by introducing a one-row line defect. Both the numerical and experimental methods are based on the time of flight approach for an optical pulse. An increase of the group index by approximately 45 times (from 4 to 155) has been observed when approaching the cutoff of the fundamental photonic bandgap mode. Numerical 2D and 3D simulations of pulse dynamics in the waveguide made by the time-domain method shows excellent agreement with measured data in most of the band. These group index values in a photonic crystal waveguide are to the best of our knowledge the largest numbers reported so far by direct tracking of pulse propagation.
We demonstrate a 57.6-km-long linear photonic crystal fiber (PCF) transmission experiment using a recirculating loop with a 19.2-km PCF spool. A 10-Gbit/s non-return-to-zero signal was transmitted over PCF transmission fiber without dispersion compensation.
We demonstrate all-optical label encoding and updating for an orthogonally labeled signal in combined IM/FSK modulation format utilizing semiconductor lasers, semiconductor optical amplifiers and electro-absorption modulators. Complete functionality of a network node including two-hop transmission and all-optical label swapping is also experimentally demonstrated with overall penalty of less than 2 dB, proving the orthogonal IM/FSK labeling scheme to be a feasible solution for future optically labeled networks.