We theoretically investigate the photonic band gap in one-dimensional photonic crystals with a graded multilayer structure. The proposed structure constitutes an alternating composite layer (metallic nanoparticles embedded in TiO2 film) and an air layer. Regarding the multilayer as a series of capacitance, effective optical properties are derived. The dispersion relation is obtained with the solution of the transfer matrix equation. With a graded structure in the composite layer, numerical results show that the position and width of the photonic band gap can be effectively modulated by varying the number of the graded composite layers, the volume fraction of nanoparticles and the external stimuli.

Theoretical study on the photonic band gap in one-dimensional photonic crystals with graded multilayer structure

A photonic crystal filter with silicon as defect layer in third optical window region for C-band applications is proposed and its transmittance spectra is analyzed with respect to structural and temperature variations. We have obtained two channel peaks in optical E and C band regions. Channel properties are plotted with respect to variations in each parameter. The increase in stack number resulted in reduction of separation between two channel peaks. The enhancement in defect film thickness shifted the whole spectra more into infrared region and temperature variations induced a slow drift in wavelength. So effective control of photonic band gap makes the crystal more applicable in the areas of optical communication such as waveguides, optical insulators, splitters, and micro resonators for spontaneous emission management. Also the proposed filter works well in the area of C-band applications such as for WDM system in FTTH.

Dual Channel Photonic Crystal Filter With Silicon Defects For Optical C-band Applications

We present a systematic simulation study of dimension-induced photonic band-gap tuning in two-dimensional (2-D), hexagonal lattice photonic crystals, consisting of air-holes in dielectric slabs. Photonic crystals are interesting candidates for application in various fields e.g. communication ranging from optical to THz regime, sensing, spectroscopy, imaging etc., using their property to trap and harness light and to produce high-Q resonances by the principle of localization and photonic bandgap formation. The insensitivity towards launched light wavelength shown herein by the bandgap response of a given 2-D planar photonic crystal is promising for enabling cheaper visible or NIR light sources to produce desired response in Mid-IR wavelengths with ease. The structures and material studied lie within the range of popular fabrication methodology. The results show that silicon photonic crystals, operated at 1.55 µm, can produce sharp resonances and large band transmission in Mid-IR wavelengths (3–5 µm) as well.

Nabanita Acharjee

Papers

Dimensional Modification Induced Band Gap Tuning in 2D-Photonic Crystal for Advanced Communication and Other Application