Resonant leaky modes can be induced on dielectric, semiconductor, and metallic periodic layers patterned in one or two
dimensions. Potential applications include bandpass and bandstop filters, laser mirrors, ultrasensitive biosensors,
absorption enhancement in solar cells, security devices, tunable filters, nanoelectromechanical display pixels,
dispersion/slow-light elements, and others. As there is now a growing realization worldwide of the utility of these
devices, it is of interest to summarize their physical basis and present their applicability in photonic devices and systems.
In particular, we have invented and implemented highly accurate, label-free, guided-mode resonance (GMR) biosensors
that are being commercialized. The sensor is based on the high parametric sensitivity inherent in the fundamental
resonance effect. As an attaching biomolecular layer changes the parameters of the resonance element, the resonance
frequency (wavelength) changes. A target analyte interacting with a bio-selective layer on the sensor can thus be
identified without additional processing or use of foreign tags. Another promising pursuit in this field is development of
optical components including wideband mirrors, filters, and polarizers. We have experimentally realized such devices
that exhibit a minimal layer count relative to their classical multilayer thin-film counterparts. Theoretical modeling has
shown that wideband tuning of these filters is achievable by perturbing the structural symmetry using
nano/microelectromechanical (MEMS) methods. MEMS-tuned resonance elements may be useful as pixels in spatial
light modulators, tunable lasers, and multispectral imaging applications. Finally, mixed metallic/dielectric resonance
elements exhibit simultaneous plasmonic and leaky-mode resonance effects. Their design and chief characteristics is
The microjet printing method of micro-optical element fabrication is being used to make arrays of high-performance hemi-elliptical and hemi-cylindrical microlenses for potential use in applications such as collimation of edge-emitting diode laser array beams. The printing method enables both the fabrication of very fast (e.g., f/0.75) microlenses and the potential for reducing costs and increasing flexibility in micro-optics manufacture. The process for fabricating anamorphic microlenses, including those of square or rectangular shape, involves the dispensing and placing of precisely sized microdroplets of optical material onto optical substrates, and then controlling their coalescence and solidification. By varying the number, diameter and spacing of adjacent microdroplets of optical materials deposited at elevated temperatures onto heated substrate, both the dimensional aspect ratios and the ratio of `fast'- to-`slow' focal lengths of a printed hemi-elliptical microlens may be varied over a very wide range. Arrays of hemi-elliptical and hemi-cylindrical microlenses on the order of 100 - 300 micrometers in width and 150 micrometers to 20 mm long, with focal length ratios (fast/slow) from 1 (circular) to 0 (cylindrical), have been printed. A model for predicting printed hemi-elliptical microlens focal lengths from printed lenslet geometry is illustrated, along with an interferometric method of detecting lenslet defects and aberrations.
Microjet printing methods are being utilized for data-drive fabrication of micro-optical elements such as refractive lenslet arrays, multimode waveguides and microlenses deposited onto the tips of optical fibers. Materials used for microjet printing of micro-optics to date have included optical adhesives and index-tuned thermoplastic formulations dispensed at temperatures up to 200 degree(s)C onto optical substrates and components. By varying such process parameters as numbers and locations of deposited microdroplets, print head temperature and orifice size, and target substrate temperature and surface wetability, arrays of spherical and cylindrical plano-convex microlenses have been fabricated with dimensions ranging from 80 micrometers to 1 mm to precision levels of just a few microns, along with multimode channel waveguides. Optical performance data such as lenslet f/#s and far-field diffraction patterns are presented, along with beam-steering agility data obtained with an optical telescope system assembled from microlens arrays printed by this process.