Engineering the quality factors of coupled-cavity modes in photonic crystal slabs

Abstract

The authors present a tight-binding approach to calculating the quality factor, or Q, of the modes of coupled-cavity systems in photonic crystal slabs. They show how this approach can be used to engineer coupled-cavity waveguides and arrays so as to maximize the Q of the modes. Due to destructive interference of the out-of-plane radiation from individual cavities, the Q of some coupled-cavity modes can be much higher than the Q of the individual cavities. An array with as few as 25 coupled cavities can produce isolated modes with Qs more than an order of magnitude greater than the Q of the constituent cavities, providing an alternative approach to obtaining high-Q modes.