Wide tunability and ultralarge birefringence with 3D hollow waveguide Bragg reflector

A tunable Bragg reflector based on a 3D hollow waveguide (HWG) has been proposed. Ultrawide tuning ranges of 152 nm and 164 nm, respectively, in Bragg wavelengths of TE and TM modes of the Bragg reflector have been presented experimentally. With a 3D hat-shaped HWG, a giant birefringence of 0.012 has been demonstrated that can be varied with a variable air core to realize tunable polarization-manipulating devices. The ultrawide tuning in Bragg wavelength can be utilized to make a number of widely tunable photonic devices based on the proposed 3D HWG Bragg reflector.