Nilanjan Mukhopadhyay

Abstract: Phase retarders normally exhibit strong wavelength dependence. However, for use with polychromatic light, achromatic retarders, which exhibit ideally nearly identical characteristics over a wide wavelength region, are in demand. Designing such a superachromatic retarder is a challenging task for an optical system designer where retardation will be almost constant within a wide range of wavelengths. The present investigation considers a system consisting of wave plates made of different materials, which focus on near-infrared wavelength range, viz. 800 to 2000 nm. Here, a flower pollination algorithm has been used for this nonlinear optimization problem. With the help of the mentioned optimization technique, the optimal values of thicknesses of wave plates are calculated for which the system act as a quarter-wave plate. The obtained result shows a significant improvement in terms of maximum deviation of retardation for the above-mentioned wavelength range. The proposed methodology holds promise for optimizing the design of optical systems.

TL;DR: In this paper, the authors proposed a four-element multi-crystal (Calcite; Quartz; KDP; Rutile) quarter wave retarder for SWIR range extending from 1000 to 2300 nm with retardance variation of 90°±1.25°.

TL;DR: In this paper, a super achromatic broadband quarter-wave phase retarder consisting of four birefringent plates of different materials, i.e., KDP, crystalline quartz, ADP and ZnS has been proposed, to cover the visible, near infrared and short wave infrared regions from 400-2100 nm.

TL;DR: In this article, the construction and transmission characteristics of a narrow band-pass birefringent filter have been investigated, which is formed by a combination of two sets of retarders with a polariser in between, and two linear polarisers placed at the two extreme ends.

TL;DR: In this article, the effective index profile of a bend waveguide is transformed to an equivalent straight waveguide with the help of a suitable mapping technique and is partitioned into large number of thin sections of different refractive indices.