Potential applications of ring resonators for astronomical instrumentation

Ring resonators can be used to efficiently filter, and drop, a series of wavelengths at the resonant frequencies of the ring. Both these properties are of use for astronomical applications. The dropped signal provides a frequency comb that can be used to provide a very accurate wavelength calibration. The free spectral range of such a device can be made much larger than that from a laser frequency comb, removing the requirement to perform subsequent filtering. The filtered signal could be used to efficiently suppress specific wavelengths, e.g. those corresponding to atmospheric emission lines. We present the expected performance of devices designed for both applications and discuss their advantages and limitations.