Swati Rawal

Slow light miniature devices with ultra-flattened dispersion in silicon-on-insulator photonic crystal

We propose a silicon-on-insulator (SOI) photonic crystal waveguide within a hexagonal lattice of elliptical air holes for slow light propagation with group velocity in the range 0.0028c to 0.044c and ultra-flattened group velocity dispersion (GVD). The proposed structure is also investigated for its application as an optical buffer with a large value of normalized delay bandwidth product (DBP), equal to 0.778. Furthermore it is shown that the proposed structure can also be used for time or wavelength-division demultiplexing to separate two telecom wavelengths, 1.31 microm and 1.55 microm, on a useful time-scale and with minimal distortion.

Silicon-on-insulator photonic crystal miniature devices with slow light enhanced third-order nonlinearities

The effects of the slow-down factor on third-order nonlinear effects in silicon-on-insulator photonic crystal channel waveguides were investigated. In the slow light regime, with a group index equal to 99, these nonlinear effects are enhanced but the enhancement produced depends on the input peak power level. Simulations indicate the possibility of soliton-like propagation of 1 ps pulses at an input peak power level of 50 mW inside such a photonic crystal waveguide. The increase in the induced phase shift produced by lower group velocities can be used to decrease the size and power requirements needed to operate devices such as optical switches, logic gates, and wavelength translators.

Slow Light Propagation in Liquid-Crystal Infiltrated Silicon-On-Insulator Photonic Crystal Channel Waveguides

An SOI-based liquid-crystal (LC)-infiltrated photonic-crystal channel waveguide having rectangular air holes in a Silicon core is proposed-and has an average group index of 43 over a bandwidth of 1.02 THz, with vanishing group velocity dispersion, as well as reduced higher-order dispersion. The possible propagation losses due to coupling inefficiency are also investigated for the proposed structure. It is found that high transmission is obtained for a broad bandwidth from the output of the heterogeneous waveguide finally designed, which consists of an LC-infiltrated PhC slow waveguide surrounded by fast PhC regions on either side. The LC-infiltrated W0.7 PhC waveguide that has been designed for slow light propagation should be highly tolerant to fabrication errors-and has enhanced sensitivity in comparison with conventional PhC waveguides.

Negative refraction in visible region using nano-structured metallo-dielectric photonic crystal

An artificial engineered structure of nano-inclusion made of metallic nano-rods embedded in a dielectric (ε=12.96) matrix with hexagonal arrangement is proposed. New improved designed structure exhibits Negative Refraction (NR) in visible region by using surface plasmon wave in metallo-dielectric photonic crystal operating in a dispersion regime with anti-parallel refracted wave vector and Poynting vector. Finite Difference Time Domain (FDTD) simulations are carried out to study the reflection and transmission properties and obtained Far-field pattern. Designed structure gives NR with high transmission and act as a filter with a quality factor ≈ 102 with strong application potential in nano-optics and nano-technology.

Design and analysis of chirped photonic crystal waveguide based optical diode

In the present paper, we have carried out analysis of asymmetric light propagation in a chirped photonic crystal (PhC) waveguide. The designed structures have hexagonal arrangement and square arrangement of Silicon (Si) rods in air substrate. Dimensions of the defect rods is tailored, so that the proposed design structure work as an optical isolator. The transmission analysis of the structure reveals that it can act as an optical diode. We have plotted the extinction ratio and transmission analysis graphs for the structure and it has been observed that maximum output is obtained for telecom wavelength of 1.55μm.

Photonic crystal-based RGB primary colour optical filter

Abstract We have presented an RGB optical filter, based on photonic crystal (PhC) waveguides, with the hexagonal arrangement of GaP rods in air. It filters out the three primary colours of the visible range, red (R, λ = 648 nm), green (G, λ = 540 nm) and blue (B, λ = 470 nm). The plane wave expansion method is applied for estimating the dispersion curves and finite element method is utilized in examining the propagation characteristics of the designed PhC-based optical filter. Transmittance, extinction ratio and tolerance analysis have further been calculated to confirm the performance of the proposed optical filter to work in the visible range of optical spectrum and filter out the three primary colours (red, green, blue) along different output ports.

Soliton propagation in slow-light photonic crystal waveguides

The effects of different slow-down factors on two photon absorption and free carrier absorption in silicon-on-insulator (SOI) photonic crystal (PhC) channel waveguides are reported in this paper. It is found that, in the slow light regime, these nonlinear effects are enhanced, but that the enhancement produced depends on the input peak power level. Simulations indicate the possibility of soliton-like propagation of 111 fs pulses at 1.55 μm inside such a photonic crystal waveguide.

Slow Light Nonlinear Photonic Crystal Channel Waveguide as an All-Optical Switch

The effect of slow light on nonlinear effects in photonic crystal and increased induced phase shift produced by lower group velocities is used to decrease the size and power requirements needed to operate optical switches

Imaging for blue light

Design of left-handed plasmonic lens is presented for focusing of blue light using dispersion engineering and numerical analysis. Values of permeability and permittivity calculated by applying discrete dipole approximation.

Low velocity propagation in liquid in-filled photonic crystal waveguides

A low-loss low-velocity photonic crystal (PhC) waveguide having rectangular air holes in-filled with a liquid crystal in Si core is proposed. The possible propagation losses due to inefficient coupling are also investigated for proposed structure. It is found that high transmission is obtained for a broad bandwidth from the output of the finally designed heterogeneous waveguide consisting of a slow liquid crystal infiltrated PhC waveguide surrounded by fast PhC waveguides on both sides.