Tunable Hollow Optical Waveguide and Its Applications

The prime focus of this chapter is a hollow optical waveguide for integrated optics. Starting with a review of various novel hollow waveguide structures, physics and technology of tunable hollow waveguide have been presented with theory and experiments. With the flexible structure of hollow waveguide, a number of tunable optical functions can be realized; some of them are presented in the chapter. After giving a brief review on various hollow waveguides, we describe the basic structure and propagation characteristics of the tunable hollow waveguide. The possibility of two-dimensional (2D) confinement with a 3D hollow waveguide has been discussed. A widely tunable Bragg reflector based on hollow waveguide is then presented and the possibility of on-chip polarization control using 3D hollow waveguide has been discussed which is followed by the description of a novel tapered 3D hollow waveguide Bragg reflector for an adjustable compensation of polarization mode dispersion (PMD). The chapter closes with a discussion on future prospects of using tunable hollow waveguide in reconfigurable integrated photonic circuits and in other applications. The integration Technology for widely tunable hollow waveguide devices has been introduced and a novel hollow waveguide with vertical and lateral periodicity has then been shown with a high index contrast grating which can add extra design flexibility to control the polarizations and can be more fabrication tolerant.