Sub-threshold measurements of a photonic crystal (PC) microcavity laser operating at 1.3 microns show a linewidth of 0.10 nm, corresponding to a quality factor Q ~ 1.3x10^4. The PC microcavity mode is a donor-type mode in a graded square lattice of air holes, with a theoretical Q ~ 10^5 and mode volume Veff ~ 0.25 cubic half-wavelengths in air. Devices are fabricated in an InAsP/InGaAsP multi-quantum well membrane and are optically pumped at 830 nm. External peak pump power laser thresholds as low as 100 microWatts are also observed.

https://arxiv.org/pdf/quant-ph/0306110.pdf

Experimental demonstration of a high quality factor photonic crystal microcavity

We present a detailed theoretical and experimental study of the evanescent coupled optical microcavity modes in one-dimensional photonic bandgap structures. The coupled-cavity samples are fabricated by depositing alternating hydrogenated amorphous silicon nitride and silicon oxide layers. Splitting of the eigenmodes and formation of a defect band due to interaction between the neighbouring localized cavity modes are experimentally observed. Corresponding field patterns and the transmission spectra are obtained by using transfer matrix method (TMM) simulations. A theoretical model based on the classical wave analogue of the tight-binding (TB) picture is developed and applied to these structures. Experimental results are in good agreement with the predictions of the TB approximation and the TMM simulations.

Coupled optical microcavities in one-dimensional photonic bandgap structures : Special issue on photonic bandgaps

Bi-component hard (H) (hexaferrite) and soft (S) (spinel) ferrites nanocomposites are gaining interest scientifically and technically, not only for combining the high magnetization of spinel ferrite nanomaterials and the high coercivity of hexaferrite magnetic nanomaterials but also for the outstanding exchange-coupling behavior among hard and soft magnetic phase. The improved magnetic features lead to produce a new nanocomposite with higher microwave absorption capacity in comparison with ferrites with a single absorption mechanism. Exchange-coupled effect has a potential application based on microwave absorption, recording media, permanent magnets, biomedical and other applications. Intensive studies have been conducted on this topic to produce hard/soft (H/S) ferrite nanocomposites with establishment of exchange coupled effect between the two phases. Preparation methods, microstructure, magnetics features, microwave and dielectric properties, and applications are elaborated. Consequently, a comprehensive effort has been made to contain an original reference investigating in detail the precise outcomes of the published papers.

Review on functional bi-component nanocomposites based on hard/soft ferrites: Structural, magnetic, electrical and microwave absorption properties

Sensitivity enhancement of annular one dimensional photonic crystals temperature sensors with nematic liquid crystals

Theoretical verification of photonic crystals sensor for biodiesel detection and sensing

Low-loss Y-junction two-dimensional magneto-photonic crystals circulator using a ferrite cylinder

Photonic crystal (PhC) structures with polarized-wave-guiding property (PhC polarization waveguides) are proposed, demonstrated and applied to construct several new kinds of compact and efficient micro polarization devices in the mid and far infrared wave bands, including TE polarizers, TM polarizers, TE-downward T-shaped polarization-beam splitters (PBSs), TM-downward T-shaped PBSs and lying-T-shaped PBSs. Theoretical models for the operating mechanism of the structures are presented. The polarization devices built as applications of the PhC polarization waveguides are demonstrated by the finite-element method with the dispersion of materials being considered. Furthermore, optimized parameters are obtained by investigating the extinction ratio (EXR), the degree of polarization (DOP) and insertion loss. Moreover, structures based on PhC slabs derived from the 2D ones, together with woodpile PhC covers and substrates are suggested for the 3D version of the proposed devices for implementation. An example of the 3D-version structures shows a performance as good as that of the 2D structure. The devices proposed have relatively wide ranges of operating wavelength. Meanwhile, they are very compact in their structures and convenient for connection or coupling of signals among different optical elements, so they have the potential for wide applications in mid-and-far infrared optical devices or circuits, which are useful in remote sensing, image and vision, positioning and communications with infrared waves. Furthermore, the principle can be applied to build polarizers and PBSs in other wave bands.

Photonic-crystal structures with polarized-wave-guiding property and their applications in the mid and far infrared wave bands

Experimental evidence of the large photonic band gap in two‐dimensional square‐lattice Al2O3 rods array

T-typed photonic crystal circulator with square lattice Al2O3 rods array and NiZn-ferrite posts

A novel three-port Y-shaped circulator based on magneto-photonic crystals is first experimentally investigated. The band gaps of TE mode for the photonic crystals are calculated by plane wave expansion method. The transmission characteristics of the circulator are simulated by finite element method and the experiments are performed in the microwave regime. At the central frequency of 9.83 GHz, the optimal experimental isolation of –61.11 dB is better than the numerical results.

Dengguo Zhang

Papers

Low-loss Y-junction two-dimensional magneto-photonic crystals circulator using a ferrite cylinder

Photonic-crystal structures with polarized-wave-guiding property and their applications in the mid and far infrared wave bands

Experimental evidence of the large photonic band gap in two‐dimensional square‐lattice Al2O3 rods array

T-typed photonic crystal circulator with square lattice Al2O3 rods array and NiZn-ferrite posts

Microwave-Frequency Experiment Validation of a Novel Magneto-Photonic Crystals Circulator