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Two-dimensional, nano-scale photonic crystals (PhCs) in silicon and biocompatible polymer materials, such as: Polydimethylsiloxane (PDMS) and epoxy, are potential core structures in ultra-sensitive biosensors enhancing fluorescence emission in the near IR and visible range. A triangular PhC lattice (r/a = 0.33) of silicon pillars suspended in toluene was designed to enhance emission in the near-IR range. We present here a 27-fold enhancement of PbS-Quantum-Dot emission at 1100 nm. Moving to more biocompatible materials, we also present frequency-domain modeling results demonstrating partial photonic bandgaps for triangular PhC lattices in PDMS and epoxy. The existence of these bandgaps suggests that PhCs in polymer materials could potentially enhance visible-range fluorescence emission and become co-integrated with other on-chip components, such as microfluidic channels and optical waveguides, to produce cost-effective biosensors.

The combination of optics and microfluidics into optofluidic systems has provided a means of creating portable integrated platforms for performing fluorescence emission analyses in fieldable systems. We present here the design of a photonic crystal transducer for highly sensitive and selective fluorescence-based biomolecule detection using a reduced-size lattice nanocavity tuned for resonance at emission wavelengths. This novel approach to biosensing is based upon photonic crystal defect structures that are engineered to act as waveguides, optical resonant cavities, and nanofluidic flow channels. This paper will discuss modeling, design, and nanofabrication of optofluidic photonic crystal (PhC) transducers in silicon and GaN materials. First-order results of PhC optical property characterization will be provided. Preliminary simulations indicate that fluorescence emission intensity inside of a PhC resonant defect nanocavity is enhanced to a level 26 times greater than emission outside of a defect due to resonant optical confinement and the Purcell effect.

Periodic poling of GaN (alteration of the crystallographic direction along the c-axis) has potential for applications in photonics, sensing, and non-linear optics. One approach to periodic poling of GaN, involves Molecular Beam Epitaxy (MBE) growth of heavily Mg doped GaN which results in inversion of the surface polarity from Ga-polar to N-polar GaN. Fabrication and dry etching of the inversion layer followed by re-growth, and a subsequent highly anisotropic wet etch of re-grown N-polar regions can result in periodically poled GaN with features on either the micro or nanoscale. This paper outlines the design of GaN based photonic crystal biosensors based on periodic poling. Initial results of growth, fabrication, and theoretical modeling will be discussed.