Compact Quasi-Chaotic Optical Cavity
  A novel, 3-dimensional, convex, multi-pass optical cavity with partially-chaotic ray dynamics is presented. The light is localized near stable, long-path length trajectories supported by the cavity, and beam diffraction is suppressed by the phase space barriers between the regions of regular and chaotic ray dynamics that are generally present in partially-chaotic systems. For a centimeter-size cavity, the design supports meter-scale optical path lengths, suggesting future applications in trace gas detection. An exemplary cavity has been fabricated from a hollow, gold-coated, acrylic shell. Our measurements using a HeNe laser and a pulsed red diode laser for characterization of the cavity beam pattern and optical path length, respectively, confirm the theoretically predicted optical dynamics and the ability of the cavity to support meter-scale path lengths. 
Jonathan A. Fan, Evgenii E. Narimanov, and Claire Gmachl