The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

In the present work, we have investigated theoretically the optical properties of a new one-dimensional defected photonic crystal structure (1DDPC). The structure is composed of alternating layers of metamaterial (double-negative material) and high Tc superconductor material called Hg1223 defected with a dielectric material (SiO2) at the center of the structure. The transmittance spectra of the proposed structure are obtained by using the transfer matrix method (TMM). We noticed that multiple transmittance peaks within the photonic band gap (PBG) as the thickness of defect layer increases. The tunable filtering feature is obtained by varying the thicknesses of metamaterial and superconductor layer. In addition, the defect peak is red shifted as well as photonic band gap tuned to low-frequency region. Our structure is sensitive to the variation of the angle incidence. Also, defect mode shown to be blue shifted as the angle of incidence increases. The tunable filtering properties are very useful in the optoelectronic applications.

The Optical Properties of Metamaterial-Superconductor Photonic Band Gap With/Without Defect Layer

Integrated MOEMS based cantilever sensor for early detection of cancer

In this work, near infrared filtering properties in a transmission narrowband filter are theoretically investigated. The filter is a defective photonic crystal of (LH) N D(HL) N ,w hereN is the stack number, L is SiO2, H is InP, and defect layer D is an extrinsic semiconductor of n-type silicon (n-Si). It is found that there are multiple transmission peaks within the photonic band gap (PBG) as the defect thickness increases. The filtering position can be changed by varying the doping density in n-Si. That is, the peak (channel) wavelength is blued-shifted when the doping density increases. In the angle-dependent filtering property, the channel wavelength is also blued-shifted as the angle of incidence increases for both TE and TM waves. These filtering properties are of technical use in the applications of semiconductor optoelectronics.

/pdf/near-infrared-filtering-properties-in-photonic-crystal-1la594weoj.pdf

Near infrared filtering properties in photonic crystal containing extrinsic and dispersive semiconductor defect

High resolution wide range pressure sensor using hexagonal ring and micromachined cantilever tips on 2D silicon photonic crystal

Narrow band filter using 1D periodic structure with defects for DWDM systems

Analysis has been done of improvement of forward directional light extraction efficiency of light emitting diodes (LEDs) by surface patterning of different types of one-dimensional profiles on indium-zinc-oxide films developed recently by our group using sol–gel technique. Finite-difference time-domain simulations by MEEP software have been used for this purpose. From the analysis, it is found that the patterned film is suitable for near-infrared LED. The optimized structure, which gives maximum improvement at around 1.040 μm wavelength, is determined and fabricated using soft lithography. Further enhancement of the light output of the LED with the fabricated gratings is possible by introducing an interlayer within the top contact layer. The mathematical formulation of the coupling of light in structured/multilayered surfaces is also discussed.

Further enhancement of light extraction efficiency from light emitting diode using triangular surface grating and thin interface layer

In this work, design of a photonic crystal (PhC) based structure is proposed for efficient splitting of light from broadband Light Emitting Diode (LED) into multiple narrowband sources. InP based transverse junction LED is considered. A vertical stack of two-dimensional (2D) square lattice PhC made up of GaAs/air is placed on top of this LED. 2D periodicity of the PhC is in the vertical plane of the top surface of the LED. On removal of a few GaAs rods the broadband light is focussed by effect of superlensing on the resulting T-type channel. The simulated result is studied by creation of curved air hole on the superlensing PhC. Only TM polarized light of specific wavelength ranges from the LED source is considered for narrowbands splitting as the TE polarized light does not have suitable bandgap there.

Efficient splitting of broadband LED light into narrowbands using superlensing effect and defects on its top 2D photonic crystal

Abstract. A photonic crystal (PhC)-based structure is designed to achieve subdiffraction imaging over the entire visible wavelength range. The designed structure is a two-dimensional triangular lattice PhC formed by making circular holes in a 100-nm film of electro-optic lithium niobate (LiNbO3) grown on indium tin oxide. The analysis is done by using MEEP and MPB softwares. This shows that by applying a voltage within ±460  V, equal frequency contour can be obtained for specific values of frequencies, which corresponds to wavelength (λ) in visible range (389 to 757 nm). This indicates that the designed structure will have effective negative refraction and hence subdiffraction imaging over the entire visible wavelength (frequency) range. By placing this type of PhC structure in front of the objective, the resolution of the conventional imaging system can be increased.

Rajib Ghosh

Papers

Narrow band filter using 1D periodic structure with defects for DWDM systems

High resolution wide range pressure sensor using hexagonal ring and micromachined cantilever tips on 2D silicon photonic crystal

Further enhancement of light extraction efficiency from light emitting diode using triangular surface grating and thin interface layer

Efficient splitting of broadband LED light into narrowbands using superlensing effect and defects on its top 2D photonic crystal

Design of electro-optic photonic crystal structure for subdiffraction imaging over the entire visible wavelength range