|Todd H. Stievater
We are investigating the scientific and technological properties of nanophotonic devices, nano-optomechanical systems, and semiconductor heterostructures. The high-index contrast, small feature sizes, and low loss afforded by new precision lithography in semiconductors and related materials enable the creation and study of entirely new types of nanophotonic optical devices. Our research ranges from fundamental scientific investigations to device development. Specific areas of interest include:
(1) Nonlinear Optics. We are investigating sum- and difference-frequency generation via birefringent phase-matching in nanophotonic- waveguides for efficient frequency mixing. We are also studying third-order optical nonlinearities in nanophotonic waveguides, such as Raman scattering and frequency comb generation. We also use nonlinear techniques such as waveguide Raman scattering to study new nanophotonic materials.
(2) Cavity Optomechanics. We are investigating new materials and architectures for integrated cavity opto-mechanics including novel cavities; innovative waveguide approaches (e.g. weak confinement, slot-modes, hybrid plasmonic, etc.); and novel sensors, oscillators, and modulators of interest to the Navy and DOD.
(3) Electro-Optics and Microwave Photonics. We are combining wafer-bonding and substrate removal techniques with state-of-the-art electro-optic materials and high-k dielectrics to investigate efficient, low-loss electro-optic modulation at ultra-high frequencies. We are also investigating integrated microwave photonics devices to perform electro-optic signal processing of high-frequency analog data using photonic integrated circuits.
(4) Optical Sensing. We are making functionalized, highly evanescent waveguides in the near-IR, midwave-IR, and longwave-IR for spectroscopic detection of trace-gases, biological compounds, and other analytes of interest. We have developed methods such as waveguide-enhanced Raman spectroscopy (WERS) and waveguide infrared absorption spectroscopy (WIRAS) for on-chip biological and chemical sensing.
(5) Optical Phased-Arrays. We are investigating integrated photonics for all-optical phased arrays and nonmechanical beam steering, focusing on applications of interest for the DOD.
(6) Cold-Atom Nanophotonics. We are investigating nanophotonic waveguides for optical traps for cold atoms using the evanescent fields above the waveguides.
(7) Integrated Photonics and Nanophotonic Waveguides. We are investigating novel approaches and techniques to fabricate, use, and characterize subwavelength-scale waveguides, including the development of kits of components for PIC foundries and the development of a low-loss silicon nitride platform for visible integrated photonics.
Our work includes modeling and design, epitaxial growth, sample processing and device fabrication, and optical measurements and analysis. Research is conducted in collaboration with the Electronics Science and Technology Division, the Nanoscience Institute, AIM Photonics, as well as numerous other collaboratos within the Department fo Defense.
Waveguide; Nanophotonics; SOI; GaAs; InP; Nonlinear optics; Integrated photonics; DFG; Raman spectroscopy; Electro-optics; Wafer-bonding; Long-wave IR;
Mid-wave IR; Microwave photonics; Slot waveguide; Optical sensing; Optical phased-array;