Microring and microdisk resonator integrated circuits on a silicon chip

Abstract

We report our latest experimental and numerical work on silicon microresonator passive and electro-optic active devices. On the passive device front, we demonstrate an electrically tunable silicon microring notch filter for converting 3.6-Gbps non-return-to-zero (NRZ) data format to return-to-zero (RZ)-like data format. We show that the converted RZ-like data quality highly depends on the notch filter extinction ratios. On the active device front, we demonstrate a silicon microring modulator using a double-coupled U-bend waveguide as a feedback and a pair of laterally integrated injectiontype p-i-n diodes for bias/signal modulation. We show that the microring modulator extinction ratios are electrically controlled by applying a DC-bias across either the feedback-waveguide or the microring while applying a modulation signal across the other p-i-n diode. We also propose silicon microdisk modulators with selectively integrated depletiontype Schottky diodes. Our numerical simulations suggest that the microdisk structures can be advantageous compared with microring structures. We show that electrical rise time on the order of a few ps is feasible using microdisks. We also allude to on-going work on extending the microresonator devices discussed here to building functional silicon optoelectronics integrated circuits.Keywords: silicon microring, silicon microdisk, silicon microresonators, free-carrier plasma dispersion, silicon photonics, silicon optoelectronics integrated circuits INTRODUCTIONSilicon micrometer-scale ring/disk resonator devices that are fabricated by the mature CMOS-compatible processes have recently attracted considerable interests for optical signal processing applications on photonics chips including in nextgeneration wavelength-agile optical networks [1], as components for optical interconnects on computer chips [2-4], and as on-chip refractive-index-based label-free biosensors [5,6]. As an integrated narrowband optical filter, silicon microring resonator-based channel add-drop and notch filters have attained high quality factors Q ~ 10 5 [7,8]. Majority of the demonstrated silicon microresonators are based on conventional circular/racetrack microring [7-11] and microdisk [12, 13] resonators, with alternative devices from our research group using polygonal-shaped [14-17] and spiral-shaped [18, 19] microdisk resonators. Various silicon microresonator-based switches and modulators using thermooptical [20], mechanical [21], optical [22], and electrooptical (EO) [23-25] mechanisms have been demonstrated. Among these microresonator tuning methods, EO tuning by means of the well-understood free-carrier plasma dispersion effect in silicon [26] offers an appealing combination of beyond-GHz-speed switching, as well as the possibility of electronic control using CMOS circuits on the silicon substrate. Specifically, Xu et al. in their pioneering work [23] demonstrated GHz-speed silicon microring modulators with laterally integrated injection-type p-i-n diodes. Owing to the high-Q resonance sensitivity to minu...

Whispering gallery modes at 800 nm and 1550 nm in concentric Si-nc/Er:SiO2 microdisks

“…Si photonics can provide low loss waveguides, high band width, and immunity to electromagnetic noise. Numerous Si components have been investigated including waveguides, modulators, detectors, and filters [1][2][3]. A missing component for the monolithic integration of Si photonics is a Si-based light emitter.…”