A tunable optical resonator whose resonance frequency is determined by a light signal introduced into the resonator. The resonator includes an optical cavity[10, 306] having a first mirror[13] and a second mirror[14]. The first mirror[13] and second mirror[14] are supported relative to one another such that the distance between the first and second mirrors may be altered by applying a force to said second mirror[14] thereby altering the resonance frequency of said cavity. The resonator includes a light input port[13] for receiving a tuning light signal, and a light signal generator for generating the tuning light source[302]. The tuning light signal is introduced into the optical cavity[10,306] such that the tuning light signal is reflected between the first and second mirrors. In the absence of the tuning light signal, the resonator has a resonance characterized by a resonance response curve centered at λ 0 . The tuning light signal has a wavelength λ 1 within said resonance response curve and sufficient power to cause said resonance response curve to shift such that the resonance response curve is now centered at λ 2 , where λ 2 >λ 1 . In one embodiment of the invention, a circuit[403] for monitoring the light leaving the resonator is utilized to control the wavelength and/or amplitude of the tuning light signal such that the light leaving the resonator has a predetermined wavelength.