title: Properties of fluoride microresonators for mid-IR applications.
abstract: We study crystalline fluoride microresonators for mid-infrared (mid-IR) applications. Whispering gallery mode resonators were fabricated with BaF2, CaF2, and MgF2crystals. The quality factors were measured at wavelengths of 1.56 and 4.58 μm. The impacts of post-fabrication processing, impurities, and surface water are highlighted. The mid-IR optical losses due to multiphoton absorption are measured. It is found that MgF2resonators have a room temperature Q-factor of 8.3×106at a wavelength of 4.58 μm, limited by multiphoton absorption.
authors.forename: Ivan S
authors.initials: IS
authors.lastname: Grudinin
authors.forename: Kamjou
authors.initials: K
authors.lastname: Mansour
authors.forename: Nan
authors.initials: N
authors.lastname: Yu