|Stievater, Todd H.
We are investigating the properties of nanophotonic devices and nano-optomechanical systems for novel photonics technologies. The high-index contrast and small feature sizes afforded by new precision patterning and etching technologies in semiconductors enables the study of entirely new nanomachined and nanomechanical optical devices. Our research ranges from fundamental investigations (such as electro-optical and nonlinear optical effects, optical cooling, and energy dissipation) to device development (e.g., quantum well modulators, fiber optic sensors, and integrated optical filters). Our current work can be grouped into three broad categories:
(1) Suspended III-V semiconductor waveguides. Because of the zinc-blende crystal structure of these semiconductors, the electro-optic, nonlinear optical, and optomechanic properties are fundamentally different that those of silicon. By combining these properties with the high-index contrast of suspended subwavelength waveguides, these microstructures can have extremely large electro-optic phase shifts (via multiple quantum wells), highly efficient nonlinear wavelength conversion (via birefringent phase matching in thin slabs or nanoslots), and guided mode polaritons (via Raman scattering with TO phonons).
(2) Silicon-on-insulator (SOI) waveguides. SOI-based nanophotonic devices under investigation include high-Q optical filters, MEMS-based integrated optical sensing using functionalized microresonators, integrated cavity opto-mechanics, and highly-evanescent waveguides for Raman spectroscopy of chemical analytes.
(3) Surface-normal optical MEMS sensors. We are investigating micro-opto-mechanical structures that incorporate micromechanical actuation, as well as new techniques to perform mid-infrared (IR) spectroscopy using ultrasensitive interferometric techniques to read-out MEMS sensors. Sensing transduction can be based on bolometry, mass-loading, or strain.
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, and the Materials Science Division. Growth and fabrication capabilities include molecular beam epitaxy, full access to the Nanoscience Institute cleanroom, and many other microprocessing tools located throughout NRL. Measurement and characterization equipment includes a white-light profilometer, a Fourier-transform infrared spectrometer, all-band tunable diode lasers, optical spectrum analyzers, nanopositioning equipment, and a NIR spectrometer.
GaAs; InP; MEMS; Micromachining; NEMS; Photonics; Quantum wells; SOI; Waveguide;