Research Express@NCKU - Articles Digest
Research Express@NCKU Volume 23 Issue 8 - April 12, 2013 [ http://research.ncku.edu.tw/re/articles/e/20130412/2.html ]
Characterization on five effective parameters of
anisotropic optical material using Stokes
parameters-Demonstration by a fiber-type polarimeter
Yu-Lung Lo
*, Thi-Thu-Hien Pham, Po-Chun Chen
Professor of Department of Mechanical Engineering, College of Engineering, National Cheng Kung University
loyl@mail.ncku.edu.tw
Optics Express, 18(9), 9133-9150, Apr 2010
A
nisotropic optical materials are used for a diverse range of applications, and thus many methods have been proposed for measuring their fundamental optical properties including the linear birefringence (LB), circular birefringence (CB), linear diattenuation (LD), and circular diattenuation (CD). The present study proposes a method based on the Mueller matrix formulation and the Stokes parameters for determining the effective optical parameters (i.e. the principal axis angle, phase retardance, diattenuation axis angle, diattenuation and optical rotation angle) of an anisotropic material on the LB, LD, andCB. The LB /CB properties and LD properties are decoupled within the analytical model. The analytical method is then integrated with a genetic algorithm to extract the optical properties of samples with linear birefringence property using a fiber-based polarimeter. The result demonstrates the feasibility of analytical model in
characterizing five effective parameters of anisotropic optical material. Also, it confirms that the proposed fiber-based polarimeter provides a simple alternative to existing fiber-fiber-based probes for parameter measurement in the near field or the remote environment. A low birefringence fiber-based polarimeter based on effective parameters and genetic algorithm without using a fiber polarization controller is first proposed confirmatively.
The ability of the proposed analytical model to extract the five effective optical parameters of interest over the measurement ranges is verified using a simulation technique. Thereafter, simulations are performed to evaluate the accuracy of the results obtained from the proposed method for composite samples with varying degrees of LB/CB, and LD given an assumption of errors ranging from -0.5% ~ +0.5% in the values of the output Stokes parameters. The experiments as shown in Fig. 2 are conducted in two different cases of four and five effective parameters being assumed in an optical fiber. By doing this way, it is understood that an assumption on the five parameters additionally considering CB in an optical fiber can be effectively characterized in the optical fiber.
Fig. 1. Schematic diagram of fiber-type polarimeter used to extract LB sample parameters using genetic algorithm.
Research Express@NCKU - Articles Digest
Fig. 2. Experimental results for birefringence of quarter-wave plate using a fiber-based polarimeter (a) without considering CB, (b) with considering CB in an optical fiber.
