Vernier effect in asymmetrical ring resonator arrays

By properly adjusting the spacing between ring resonators in linear parallel arrays, it is possible to selectively depress modes of the transmission spectra and effectively increase the free spectral range of the individual rings. This enables the synthesizing of a transmission response with modal spacing that otherwise would require much smaller ring diameters. Examples of filters with narrowband and flat-top passbands, which are desirable for all-optical wavelength division multiplexed networks, are given.