Joris Van Campenhout

Integrated NiSi waveguide heaters for CMOS-compatible silicon thermo-optic devices

We report the performance of NiSi-based heaters integrated with submicrometer silicon waveguides. The heaters were fabricated using a standard complementary metal-oxide-semiconductor (CMOS) silicidation process on a thin silicon slab laterally connected with a silicon rib waveguide. The intrinsic properties of such NiSi waveguide heaters were characterized by using them as thermo-optic phase shifters in a Mach-Zehnder interferometer. The power consumption P(pi) for obtaining a pi phase shift was measured to be as low as 20 mW, using CMOS-compatible drive voltages. The time constant of the thermo-optic response was less than 2.8 mus. Simulations suggest that a further reduction in the power consumption P(pi) is feasible.

Design of a digital, ultra-broadband electro-optic switch for reconfigurable optical networks-on-chip.

We present a novel design for a noise-tolerant, ultra-broadband electro-optic switch, based on a Mach-Zehnder lattice (MZL) interferometer. We analyze the switch performance through rigorous optical simulations, for devices implemented in silicon-on-insulator with carrier-injection-based phase shifters. We show that such a MZL switch can be designed to have a step-like switching response, resulting in improved tolerance to drive-voltage noise and temperature variations as compared to a single-stage Mach-Zehnder switch. Furthermore, we show that degradation in switching crosstalk and insertion loss due to free-carrier absorption can be largely overcome by a MZL switch design. Finally, MZL switches can be designed for having an ultra-wide, temperature-insensitive optical bandwidth of more than 250 nm. The proposed device shows good potential as a broadband optical switch in reconfigurable optical networks-on-chip.

Carrier-injection-based electro-optic modulator on silicon-on-insulator with a heterogeneously integrated III-V microdisk cavity

A compact electro-optic modulator on silicon-on-insulator is presented. The structure consists of a III-V microdisk cavity heterogeneously integrated on a silicon-on-insulator wire waveguide. By modulating the loss of the active layer included in the cavity through carrier injection, the power of the transmitted light at the resonant wavelength is modulated; approximately 10 dB extinction ratio and 2.73 Gbps dynamic operation are demonstrated without using any special driving techniques.

A 3.9ns 8.9mW 4×4 silicon photonic switch hybrid integrated with CMOS driver

The emerging field of silicon photonics [1–3] targets monolithic integration of optical components in the CMOS process, potentially enabling high bandwidth, high density interconnects with dramatically reduced cost and power dissipation. A broadband photonic switch is a key component of reconfigurable networks which retain data in the optical domain, thus bypassing the latency, bandwidth and power overheads of opto-electronic conversion. Additionally, with WDM channels, multiple data streams can be routed simultaneously using a single optical device. Although many types of discrete silicon photonic switches have been reported [4–6], very few of them have been shown to operate with CMOS drivers. Earlier, we have reported two different 2×2 optical switches wirebond packaged with 90nm CMOS drivers [7,8]. The 2×2 switch reported in [7] is based on a Mach-Zehnder interferometer (MZI), while the one reported in [8] is based on a two-ring resonator.

Ultra-broadband, low-power, 2×2 electro-optic switch using sub-micron silicon waveguides

We present a broadband Mach-Zehnder electro-optic switch capable of simultaneously routing multiple channels within 110-nm optical bandwidth with only 3.1-mW power consumption and a 4-ns switching time. Switching bandwidth is maintained over 30°C temperature variation.