We propose and demonstrate a mechanism for small-modal-volume high-Q cavities based on an anomalous uniform waveguide mode that has zero group velocity at a nonzero wave vector. In a short piece of a uniform waveguide with a specially designed cross section, light is confined longitudinally by small group-velocity propagation and transversely by a reflective cladding. The quality factor Q is greatly enhanced by the small group velocity for a set of cavity lengths that are separated by approximately pi/k_0, where k_0 is the longitudinal wave vector for which the group velocity is zero.
© 2005 Optical Society of America
Mihai Ibanescu, Steven G. Johnson, David Roundy, Yoel Fink, and J. D. Joannopoulos, "Microcavity confinement based on an anomalous zero group-velocity waveguide mode," Opt. Lett. 30, 552-554 (2005)