Michael J. Shaw

A platform for multiplexed sensing of biomolecules using high-Q microring resonator arrays with differential readout and integrated microfluidics

We demonstrate chemical/biological sensor arrays based on high quality factor evanescent microring waveguide resonators in a process that is compatible with CMOS fabrication, glass microfluidic integration, and robust surface chemistry ligand attachment. We cancel out any fluctuations due to liquid temperature variations through a differential dual sensor design. Using laser locking servo techniques we attain detection sensitivities in the ng/ml range. This combination of silicon photonic sensors, robust packaging, high sensitivity and arrayed design is capable of providing a platform for multiplexed chem-bio sensing of molecules suspended in solution.

Fabrication techniques for creating a thermally isolated TM-FPA (thermal microphotonic focal plane array)

A novel fabrication strategy has produced optical microring-resonator-based thermal detectors. The detectors are based on the thermo-optic effect and are thermally isolated from a silicon wafer substrate so as to maximize the temperature excursion for a given amount of incident radiation and minimize the impact of thermal phonon noise. The combination of high-Q, thermal isolation, and lack of Johnson noise offers thermal microphotonic detectors the potential to achieve significantly greater room temperature sensitivity than standard bolometric techniques. Several batch fabrication strategies were investigated for producing thermal microphotonic detectors using waveguide materials such as LPCVD Silicon Nitride (Si3N4) on Oxide and Silicon on Insulator (SOI). Fabrication challenges and loss reduction strategies will be presented along with some initial infrared detection results.

Microphotonic Thermal Detectors and Imagers

We present the theory of operation along with detailed device designs and initial experimental results of a new class of uncooled thermal detectors. The detectors, termed microphotonic thermal detectors, are based on the thermo-optic effect in high quality factor (Q) micrometer-scale optical resonators. Microphotonic thermal detectors do not suffer from Johnson noise, do not require metallic connections to the sensing element, do not suffer from charge trapping effects, and have responsivities orders of magnitude larger than microbolometer-based thermal detectors. For these reasons, microphotonic thermal detectors have the potential to reach thermal phonon noise limited performance.

Ultralow-loss silicon ring resonators

We experimentally demonstrate silicon ring resonators with internal quality factors of Q 0 =2.2×107, corresponding to record 2.7-dB/m losses. We show that the losses are bend-loss-limited, indicating that the loss limit for silicon has not been reached.

Observation of Low-Contrast All-Optical Switching in Silicon Nitride Microdisks Based on the Zeno Effect

Low-contrast all-optical Zeno switching has been demonstrated in a Silicon Nitride microdisk resonator surrounded by hot Rubidium vapor. The device is based on the suppression of the cavity field buildup due to non-degenerate two-photon absorption.