Publications

The anchoring energy of liquid crystals was shown to be tunable by surface nanopatterning of periodic lines and spaces. Both the pitch and height were varied using hydrogen silsesquioxane negative tone electron beam resist, providing for flexibility in magnitude and spatial distribution of the anchoring energy. Using twisted nematic liquid...

Single-pulse irradiation of Au and Ag suspensions of nanospheres and nanodisks with 532-nm 4-ns pulses has identified complex optical nonlinearities while minimizing material damage. For all materials tested, we observe competition between saturable absorption (SA) and reverse SA (RSA), with RSA behavior dominating for intensities above ~50 MW/cm^2. Due to...

We have developed a remote detection system consisting of commercially available retroreflective material coated with an analyte-specific colorimetric dye. Quantitative performance modeling predicts that, given the appropriate indicator dye, a system with a 10 cm optic and eye-safe illumination should be capable of detecting small droplets of contamination at kilometer...

A highly scalable approach for producing surface-enhanced Raman spectroscopy substrates is introduced. The novel method involves assembling individual nanoparticles in pre-defined templates, one particle per template, forming a high denisity of nanogaps over large areas, while decoupling nanostructure synthesis from placement.

The International Technology Roadmap for Semiconductors is the go-to standard for predicting future technology requirements and driving global research and development in the semiconductor industry. This article serves as your roadmap to what it all means for optical lithography over the next 10 to 15 years.

Optical limiting by suspensions of Au nanoparticles is enhanced by several orders of magnitude with the use of complex plasmonic shapes, such as spined "nanourchins," instead of nanospheres. Similar enhancements are observed by changing the material of nanospheres from Au to Ag. The experiments, measuring intensity-dependent transmission over a wavelength...

Noncontact detection of the homemade explosive constituents urea nitrate, nitromethane and ammonium nitrate is achieved using photodissociation followed by laser-induced fluorescence (PD-LIF). Our technique utilizes a single ultraviolet laser pulse (~7 ns) to vaporize and photodissociate the condensed-phase materials, and then to detect the resulting vibrationally-excited NO fragments via laser-induced...

The development of a technique with the ability to detect trace quantities of explosives at a distance is of critical importance. In numerous situations when explosive devices are prepared, transported, or otherwise handled, quantifiable amounts of the explosive material end up on surfaces. Rapid detection of these chemical residues in...

We investigate the remote detection of explosives via a technique that vaporizes and photodissociates the condensed-phase material and detects the resulting vibrationally excited NO fragments via laser-induced fluorescence. The technique utilizes a single 7 ns pulse of a tunable laser near 236:2nm to perform these multiple processes. The resulting blue-shifted...

MIT Lincoln Laboratory has developed a concept that could enable remote (10s of meters) detection of trace explosives' residues via a field-portable laser system. The technique relies upon laser-induced photodissociation of nitro-bearing explosives into vibrationally excited nitric oxide (NO) fragments. Subsequent optical probing of the first vibrationally excited state at...