Optical Fiber Interferometers and Their Applications

Interference as a wave characteristic of the electromagnetic wave has many applications in science, technology and medicine (Grattan & Meggit, 1997; Wang et al., 2011). The fringe visibility of the first order interference experiments such as the famous double slit Young experiment and Michelson interferometer, is determined by the first order correlation function (Gerry & Knight, 2005). The first order interference is also called the field interference. In Hanbury-Brown and Twiss (HBT) experiment, fringes are due to the intensity interference and visibility is determined by the second order correlation function. (Brown & Twiss, 1956; Scully & Zubairy 2001). In quantum optics, nonlinear Lithography and quantum Lithography, interferometry based on higher order correlation function is of prime importance (Bentley & Boyd, 2004; Boto et al., 2000). However in all of these interferometries, the fringe pattern depends on the optical path difference (OPD) and feature of light source. This chapter is concentrated on the classical field interferometry. The fringe existence is a characteristic of spatial or temporal coherences between the two light beams.