Our group is interested in developing new optical materials and devices by controlling composition on lengthscales from 5 nm -500 nm. Electron-beam, atomic-force-microscopy (AFM), and optical lithographies are used in conjunction with a variety of etching and deposition technologies to produce 3D-textured structures in which the electronic and photonic eigen states can be “designed” by judicious choice of patterns, lengthscales and material combinations. The motivation is to offer optical device engineers a more diverse range of material options when developing next and next-next generation technologies.
The nanofabrication is largely done in a cleanroom processing facility that includes optical lithography, e-beam and sputter-deposition systems, an ECR remote plasma etcher, a scanning electron microscope, and a rapid thermal annealer. Use is also made of larger scale nanofabrication facilities around the world. We have a wide range of optical instrumentation for linear and nonlinear, continuous wave and time-resolved (with 100 fs resolution), spectroscopic investigations of our samples. A strong emphasis is placed on developing quantitative, but heuristic numerical models to help design and understand the properties of interest. Examples of recent and on-going research projects include:
- Nonlinear properties of single-mode ridge waveguides in silicon-on-insulator wafers
- Second order nonlinear properties of “intrinsic” 2D waveguide
- Second order nonlinear properties of 3D defect states in planar photonic crystals
- Site-selective coupling of PbS(e) nanocrystals and high-Q SOI-based photonic microcavities
- Integration of 3D photonic microcavities with single channel ridge waveguides in SOI
- Integrated non-classical light sources in SOI
We have been further developing our superconducting nanowire single photon detectors, fabricating stand-alone versions suitable for detecting visible photons (as part of a collaboration with Vahid Sandoghdar from MPI Erlangden). These are currently being tested.
We are also characterizing the four wave mixing response of our unique triple photonic crystal coupled microcavity photonic circuits. These are intended to be used as a heralded single photon source in our silicon photonic circuits. One more design iteration will likely be required before the source can be used at a high coincidence count rate.
Our other work has been concentrated on quantifying the optical trapping dynamics of high-aspect-ratio gold nanorods in our slot microcavity circuits. This is in the process of being written up, and there is much more novel “strong backaction” cavity physics to be cultivated from this interesting system.