Progress towards whispering gallery mode resonator based spectroscopy in mid-infrared

We present studies of using high Q whispering gallery mode resonators in Mid-IR laser spectroscopy. Several crystalline materials have high transparency in Mid-IR wavelength region and can be made into high Q optical resonators. We report recent measurements of Q values of greater than 1x10 8 in the wavelength region longer than 3 μm using one of these materials, Magnesium Fluoride (MgF 2 ). These resonators are being used for cavity ring-down measurements, optical frequency comb generation, and their applications in Mid-IR spectroscopy