III–V based-semiconductor photonic crystals

Three-dimensional (3D) and two-dimensional (2D) photonic crystals based on III–V semiconductors are described. On the 3D photonic crystals, the development of complete photonic crystals at optical wavelengths and their applications to ultrasmall optical integrated circuits including 3D sharp bend waveguide are described. On the 2D photonic crystals, two-unique device and/or phenomena are demonstrated.     

Computing Approximating Automata for a Class of Hybrid Systems

This paper presents a new algorithm for generating finite-state automata models of hybrid systems in which the continuous-state dynamics can be switched when the continuous-state trajectory generates threshold events. The automata state transitions correspond to threshold events and the automata states correspond to portions of the threshold surfaces in the continuous state space. The hybrid system dynamics are approximated by the automata models in the sense that the languages of threshold event sequences generated by the automata contain the threshold event language for the hybrid system. Properties of the algorithm for constructing and refining the approximating automata are demonstrated and the application of approximating automata for system verification is illustrated for a switching controller for an inverted pendulum. Relationships to other approaches to hybrid system synthesis and verification are also discussed.     

Diffractionless flow of light in all-optical microchips

We introduce the concept of a hybrid 2D-3D photonic band gap (PBG) heterostructure which enables both complete control of spontaneous emission of light from atoms and planar light-wave propagation in engineered wavelength-scale microcircuits. Using three-dimensional (3D) light localization, this heterostructure enables flow of light without diffraction through micron-scale air waveguide networks. Achieved by intercalating two-dimensional photonic crystal layers containing engineered defects into a 3D PBG material, this provides a general and versatile solution to the problem of "leaky modes" and diffractive losses in integrated optics.     

Ultra-short pulse propagation in 3D GaAs photonic crystals

We have investigated ultra-short pulse propagation through 3D GaAs photonic crystals with a complete photonic band gap in the optical wavelength region. The pulse propagation was calculated by using the finite-differential time-domain (FDTD) method. This is the first time pulse shape measurements have been made using femtosecond pulses. From the experimental results, the shapes of the ultra-short pulses were found to change when the frequency was above the photonic band-gap after the propagation through the photonic crystal, corresponding to the simulation results.     

Diffractionless optical networking in an inverse opal photonic band gap micro-chip

We present a design for a photonic crystal (PC) all-optical micro-chip based on a three-dimensional (3D) inverse opal heterostructure intercalated with a two-dimensional (2D) triangular lattice photonic crystal slab. Within the 2D micro-chip layer, we demonstrate single-mode (diffractionless) waveguiding of light in air, throughout a bandwidth of more than 70 nm near 1.55 μm. This suggests that inverse opal photonic band gap (PBG) materials can facilitate on-chip optical networking functions over the telecommunication frequency band used in current-day optical fibers.