Demonstration of mid-infrared waveguide photonic crystal cavities

We have demonstrated what we believe to be the first waveguide photonic crystal cavity operating in the mid-infrared. The devices were fabricated from Ge23Sb7S70 chalcogenide glass on CaF2 substrates by combing photolithographic patterning and focus ion beam milling. The waveguide-coupled cavities were characterized using a fiber end fire coupling method at 5.2 {\mu}m wavelength, and a loaded quality factor of ~ 2,000 was measured near the critical coupling regime.