Jason J. Ackert

Wavelength Locking and Thermally Stabilizing Microring Resonators Using Dithering Signals

The bandwidth bottleneck looming for traditional electronic interconnects has driven the consideration of optical communications technologies as realized through the complementary metal-oxide-semiconductor-compatible silicon nanophotonic platform. Within the silicon photonics platform, silicon microring resonators have received a great deal of attention for their ability to implement the critical functionalities of an on-chip optical network while offering superior energy-efficiency and small footprint characteristics. However, silicon microring-based structures have a large susceptibility to fabrication errors and changes in temperature. Integrated heaters that provide local heating of individual microrings offer a method to correct for these effects, but no large-scale solution has been achieved to automate their tuning process. In this context, we present the use of dithering signals as a broad method for automatic wavelength tuning and thermal stabilization of microring resonators. We show that this technique can be manifested in low-speed analog and digital circuitry, lending credence to its ability to be scaled to a complete photonic interconnection network.

Integrated thermal stabilization of a microring modulator

An integrated silicon photodiode and heater are used to thermally stabilize a microring modulator, interfacing with external feedback circuitry to provide error-free microring modulator operation under thermal fluctuations that would normally render it inoperable.

10 Gbps silicon waveguide-integrated infrared avalanche photodiode

We have fabricated monolithic silicon avalanche photodiodes capable of 10 Gbps operation at a wavelength of 1550 nm. The photodiodes are entirely CMOS process compatible and comprise a p-i-n junction integrated with a silicon-on-insulator (SOI) rib waveguide. Photo-generation is initiated via the presence of deep levels in the silicon bandgap, introduced by ion implantation and modified by subsequent annealing. The devices show a small signal 3 dB bandwidth of 2.0 GHz as well as an open eye pattern at 10 Gbps. A responsivity of 4.7 ± 0.5 A/W is measured for a 600 µm device at a reverse bias of 40 V.

Optical detection and modulation at 2µm-2.5µm in silicon.

Recently the 2μm wavelength region has emerged as an exciting prospect for the next generation of telecommunications. In this paper we experimentally characterise silicon based plasma dispersion effect optical modulation and defect based photodetection in the 2-2.5μm wavelength range. It is shown that the effectiveness of the plasma dispersion effect is dramatically increased in this wavelength window as compared to the traditional telecommunications wavelengths of 1.3μm and 1.55μm. Experimental results from the defect based photodetectors show that detection is achieved in the 2-2.5μm wavelength range, however the responsivity is reduced as the wavelength is increased away from 1.55μm.

Silicon-on-insulator microring resonator defect-based photodetector with 3.5-GHz bandwidth

We have devised and fabricated high-speed silicon-on-insulator resonant microring photodiodes. The detectors comprise a p-i-n junction across a silicon rib waveguide microring resonator. Light absorption at 1550 nm is enhanced by implanting the diode intrinsic region with boron ions at 350 keV with a dosage of 1 × 10 13 cm −2 . We have measured 3-dB band- widths of 2.4 and 3.5 GHz at 5 and 15 V reverse bias, respectively, and observed an open-eye diagram at 5 gigabit/s with 5 V bias. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

A 10-Gb/s Silicon Microring Resonator-Based BPSK Link

We design and demonstrate for the first time an end-to-end binary phase-shift keying (BPSK) link based on silicon microring resonators, with an operational bit-rate at 10 Gb/s. The obtained bit-error-rate is below the forward error correction limit, validating the practical application of the demonstrated technique. Performance comparisons to conventional BPSK modulation and demodulation techniques are also made. The microring-based BPSK link promises a compact, energy efficient, and low-cost interconnect solution for high-capacity transceivers.

Defect-mediated resonance shift of silicon-on-insulator racetrack resonators

We present a study on the effects of inert ion implantation of Silicon-On-Insulator (SOI) racetrack resonators. Selective ion implantation was used to create deep-level defects within a portion of the resonator. The resonant wavelength and round-trip loss were deduced for a range of sequential post-implantation annealing temperatures from 100 to 300 °C. As the devices were annealed there was a concomitant change in the resonance wavelength, consistent with an increase in refractive index following implantation and recovery toward the pre-implanted value. A total shift in resonance wavelength of ~2.9 nm was achieved, equivalent to a 0.02 increase in refractive index. The excess loss upon implantation increased to 301 dB/cm and was reduced to 35 dB/cm following thermal annealing. In addition to providing valuable data for those incorporating defects within resonant structures, we suggest that these results present a method for permanent tuning (or trimming) of ring resonator characteristics.

Ring Resonator Wavelength Division Multiplexing Interleaver

In this paper, we report on the fabrication and the characterization of a ring-resonator-based interleaver/deinterleaver circuit we proposed in a previous work. The experimental and theoretical transmission spectra as well as the fabrication tolerance of the structure are investigated.

Experimental demonstration of coherent perfect absorption in a silicon photonic racetrack resonator

We present the first experimental demonstration of coherent perfect absorption (CPA) in an integrated device using a silicon racetrack resonator at telecommunication wavelengths. Absorption in the racetrack is achieved by Si+-ion-implantation, allowing for phase controllable amplitude modulation at the resonant wavelength. The device is measured to have an extinction of 24.5 dB and a quality-factor exceeding 3000. Our results will enable integrated CPA devices for data modulation and detection.

Microring resonance stabilization using thermal dithering

We present the novel mechanism of thermal dithering for breaking the symmetry of a microring resonance, and experimentally show it can be utilized to thermally stabilize a silicon microring resonator experiencing fluctuations of 3 K.