Low-loss materials for high Q-factor Bragg reflector resonators

Abstract

A Bragg resonator uses dielectric plates within a metallic cavity to confine the energy within a central free space region. The importance of the permittivity is shown with a better Q factor possible using higher permittivity materials of larger intrinsic dielectric losses. This is because the electric energy in the reflectors decreases proportionally to the square root of permittivity and the coupling to the metallic losses decrease linearly. In a sapphire resonator with a single reflector pair a Q factor of 2.34× 105 is obtained, which may be improved on by up to a factor of 2 using higher permittivity materials. © 2008 American Institute of Physics.