Photonic crystal

About: Photonic crystal is a research topic. Over the lifetime, 43424 publications have been published within this topic receiving 887083 citations.

Optical Metamaterials—More Bulky and Less Lossy

Abstract: Usually, investigators in materials science have asked: “What properties does a certain new material or structure have?” Now, the inverse problem arises: “I want to achieve certain—possibly unheard-of—material properties. How should the corresponding micro- or nanostructure look?” Examples could be: efficiently blocking acoustic noise due to a highway from a nearby village by a tailored wall, concentrating electromagnetic energy into as-tight-as-possible spaces, or avoiding reflections from a material's surface. The underlying common scheme is wave physics. Material properties that were otherwise unachievable, e.g., negative refraction and cloaking, may eventually be designed into optical metamaterials and photonic crystals. Both require tailoring of the properties (i.e., phase velocity and impedance) of an electromagnetic wave moving through the substance at the local level. In photonic crystals, the phase velocity of an electromagnetic wave moving through the crystal is controlled by tuning the photonic band structure; the impedance is determined by the electromagnetic field distributions throughout the material. In metamaterials, this amounts to tailoring the effective electric permittivity and magnetic permeability. In either case, introducing resonances is the key to controlling the local wave properties. The recent development of advanced fabrication techniques being applied to metamaterials and photonic crystals may lead to realization of such designer materials.

Slow light enhancement of nonlinear effects in silicon engineered photonic crystal waveguides

Abstract: We report nonlinear measurements on 80microm silicon photonic crystal waveguides that are designed to support dispersionless slow light with group velocities between c/20 and c/50. By launching picoseconds pulses into the waveguides and comparing their output spectral signatures, we show how self phase modulation induced spectral broadening is enhanced due to slow light. Comparison of the measurements and numerical simulations of the pulse propagation elucidates the contribution of the various effects that determine the output pulse shape and the waveguide transfer function. In particular, both experimental and simulated results highlight the significant role of two photon absorption and free carriers in the silicon waveguides and their reinforcement in the slow light regime.

Enhanced Incident Photon-to-Electron Conversion Efficiency of Tungsten Trioxide Photoanodes Based on 3D-Photonic Crystal Design

Abstract: In this study, 3D-photonic crystal design was utilized to enhance incident photon-to-electron conversion efficiency (IPCE) of WO3 photoanodes. Large-area and high-quality WO3 photonic crystal photoanodes with inverse opal structure were prepared. The photonic stop-bands of these WO3 photoanodes were tuned experimentally by variation of the pore size of inverse opal structures. It was found that when the red-edge of the photonic stop-band of WO3 inverse opals overlapped with the WO3 electronic absorption edge at Eg = 2.6–2.8 eV, a maximum of 100% increase in photocurrent intensity was observed under visible light irradiation (λ > 400 nm) in comparison with a disordered porous WO3 photoanode. When the red-edge of the stop-band was tuned well within the electronic absorption range of WO3, noticeable but less amplitude of enhancement in the photocurrent intensity was observed. It was further shown that the spectral region with a selective IPCE enhancement of the WO3 inverse opals exhibited a blue-shift in wav...

Photofabrication of three-dimensional photonic crystals by multibeam laser interference into a photopolymerizable resin

Abstract: Three-dimensional (3D) photonic crystal structures can be fabricated into photopolymerizable resins by using laser beam interference with high precision. Three laser beams interfere into a glass cell filled with a liquid photopolymerizable resin to form a hexagonal periodic structure. Rods are formed in a hexagonal arrangement after being photopolymerzed according to the 3D periodic light distribution which results from the laser’s interference. Two beams of another laser also interfere to form layers which cross perpendicular to the rod array. After photofabrication, the nonsolidified resin is removed by ethanol. The lattice constant can be selected by tuning the angles of the incident beams and the laser wavelength. We have fabricated a 500 μm×500 μm×150 μm photonic crystal structure, the lattice constant of which is 1 μm and contains 150 lateral layers.

Single-fundamental-mode photonic-crystal vertical-cavity surface-emitting lasers

Abstract: A photonic-crystal vertical-cavity surface-emitting laser (PC-VCSEL) is proposed and demonstrated. The 850-nm-PC-VCSEL shows single-mode continuous-wave operation in the entire current range. The side-mode suppression ratio is 35–40 dB for the sample with the hole pitch (Λ) 5 μm and the hole diameter (a) 3.5 μm. The guiding effect of the single-defect triangular-lattice two-dimensional photonic crystal structure is experimentally observed and is explained by the effective index model.