20 research outputs found
Low-threshold bistability of slow light in photonic-crystal waveguides
We analyze the resonant transmission of light through a photonic-crystal
waveguide side coupled to a Kerr nonlinear cavity, and demonstrate how to
design the structure geometry for achieving bistability and all-optical
switching at ultra-low powers in the slow-light regime. We show that the
resonance quality factor in such structures scales inversely proportional to
the group velocity of light at the resonant frequency and thus grows
indefinitely in the slow-light regime. Accordingly, the power threshold
required for all-optical switching in such structures scales as a square of the
group velocity, rapidly vanishing in the slow-light regime.Comment: LaTeX, 6 pages, 4 figure
Coupled-resonator-induced reflection in photonic-crystal waveguide structures
We study the resonant transmission of light in a coupled-resonator optical
waveguide interacting with two nearly identical side cavities. We reveal and
describe a novel effect of the coupled-resonator-induced reflection (CRIR)
characterized by a very high and easily tunable quality factor of the
reflection line, for the case of the inter-site coupling between the cavities
and the waveguide. This effect differs sharply from the
coupled-resonator-induced transparency (CRIT) -- an all-optical analogue of the
electromagnetically-induced transparency -- which has recently been studied
theoretically and observed experimentally for the structures based on
micro-ring resonators and photonic crystal cavities. Both CRIR and CRIT effects
have the same physical origin which can be attributed to the Fano-Feshbach
resonances in the systems exhibiting more than one resonance. We discuss the
applicability of the novel CRIR effect to the control of the slow-light
propagation and low-threshold all-optical switching.Comment: LaTeX, 11 pages, 5 figure
Arbitrary angle waveguiding applications of two-dimensional curvilinear-lattice photonic crystals
We introduce a fresh class of photonic band-gap materials, curvilinear-lattice photonic crystals, whose distinctive feature is that their individual scatterers are arranged in a curvilinear lattice. We show that adhering to some restrictions in the acceptable lattice transformations, one can achieve omnidirectional photonic band gaps for an entire subclass of such structures. We demonstrate, designing an efficient arbitrary-angle waveguide bend, that curvilinear-lattice photonic crystals can be employed for creation of original types of nanophotonic devices
Nonlinear Fano resonance and bistable wave transmission
We consider a discrete model that describes a linear chain of particles
coupled to a single-site defect with instantaneous Kerr nonlinearity. We show
that this model can be regarded as a nonlinear generalization of the familiar
Fano-Anderson model, and it can generate the amplitude depended bistable
resonant transmission or reflection. We identify these effects as the nonlinear
Fano resonance, and study its properties for continuous waves and pulses.Comment: 9 pages, 14 figure, submitted to Phys. Rev.
Highly Localized Wannier Functions For The Efficient Modeling Of Photonic Crystal Circuits
We present a novel approach for the accurate and efficient modeling of photonic crystal-based integrated optical circuits. Within this approach, the electromagnetic field is expanded into an orthogonal basis of highly localized Wannier functions, which reduces Maxwell\u27s equations to low-rank eigenvalue problems (for defect mode and waveguide dispersion calculations) or to sparse systems of linear equations (for transmission/reflection calculations through/from functional elements). We illustrate the construction of Wannier functions as well as, the subsequent determination of defect modes, waveguide dispersion relations, and the characterization of functional elements for realistic two-dimensional photonic crystal structures consisting of square and triangular lattices of air pores in a high-index matrix. Moreover, on the basis of our Wannier function calculations we suggest a novel type of broad-band integrated photonic crystal circuits based on the infiltration of low-index materials such as liquid crystals or polymers into individual pores of these systems. We illustrate this concept through the design of several functional elements such as bends, beam splitters, and waveguide crossings
Wannier Basis Design And Optimization Of A Photonic Crystal Waveguide Crossing
We employ a novel platform for the realization of tunable photonic crystal (PC) circuits together with a Wannier basis modeling and optimization scheme in order to design a broad-band waveguide crossing. The superior performance characteristics of our design include a high bandwidth (2% of the center frequency) as well as low values for crosstalk (- 40 dB) and reflection (- 30 dB). In addition, we demonstrate the robustness of the device performance against fabrication disorder. Our novel design paradigm will enable efficient and ultracompact PC-based device designs with complex functionalities. © 2005 IEEE