We present the design, simulation, and fabrication of an all-dielectric photonic crystal-based nano-sensor that detects index of refraction changes in aqueous solutions. The photonic crystal structure is designed for incorporation with an optical readout module that includes a light source, detector, and micro-optics to form a miniature integrated nanosensor. This enables reduced cost, small sample volume, and increased speed and parallelism desirable for high throughput analysis in medical diagnostics.
We use coupled optical and electronic simulations to investigate design tradeoffs in electrically pumped photonic crystal light emitting diodes. A finite-difference frequency-domain electromagnetic solver is used to calculate the spontaneous emission
enhancement factor and the extraction efficiency as a function of
frequency and of position of the emitting source. The calculated
enhancement factor is fed into an electronic simulator, which solves the coupled continuity equations for electrons and holes and Poisson's equation. We simulate a two-dimensional structure consisting of a photonic-crystal slab with a single-defect cavity, and investigate different pumping configurations for such a cavity.
There has been significant interest in the non-orthogonal modes in resonator systems in the context of the excess noise factor in laser cavities. Conventional non-orthogonal modes are created by the gain of the laser cavity during a round trip since gain makes the propagation of light non-unitary. Here, we theoretically demonstrate that these non-orthogonal modes can also be generated in passive photonic crystal systems. We further show that it can have a broader implication in optical resonator systems. In particular, we probe the characteristics of non-orthogonal modes in a resonator system by looking at the transport properties.
We show that tunable photonic band gap materials offer new opportunities for device applications. Optical switches or sensors that are far more compact and sensitive, for instance, can be constructed when we introduce either optical or mechanical tunability into photonic crystal structures. Furthermore, when we tune the photonic crystal while a photon is inside the crystal, the crystal can exhibit qualitatively different optical physics effects. As a particularly exciting example, we show that light can in fact be completely stopped in a tunable photonic crystal, and the conventional delay bandwidth product limit in resonator optics can be completely overcome.
Using both analytic theory, and first-principles finite-difference time-domain simulations, we introduce several novel mechanically tunable photonic crystal structures consisting of coupled photonic crystal slabs. These structures exploit guided resonance effects which give rise to strong variation of transmission for normally incident light. First, when the two slabs are separated apart by a few wavelengths, such a coupled slab structure behaves as a miniaturized Fabry-Perot cavity with two photonic crystal slabs acting as highly reflecting mirrors. Therefore, the transmission through the structure is highly sensitive to the spacing between the slabs. Second, when the two slabs are in proximity to each other, the evanescent tails of the resonance start to overlap. Exploiting the evanescent tunneling, we introduce a new type of optical all-pass filter. The filter exhibits near complete transmission for both on and off resonant frequencies, and yet generates large resonant group delay. Thus, we expect the coupled photonic crystal slab structures to play important roles in micro-mechanically tunable optical sensors and filters.
Photonic crystal structures open new possibility for the construction of novel optical switch structures that are highly compact and functional. In this paper, we introduce two novel examples of photonic crystal switches: a mechanically switchable photonic crystal filter structure, and a low-power and high-speed all-optical transistor based upon cross waveguide geometry in photonic crystals.