Abstract: A system for measurement of environmental parameters, using an optomechanical cavity in the end of an optical fiber. A single unmodulated CW laser excites the cavity, which has one reflective element fixed within the end of the fiber and the facing reflector being the surface of a mechanical element, supported over the cavity at the end of the fiber so that it can vibrate at its natural resonance frequency. The length of the cavity “vibrates” at the same frequency as the mechanical element, so that the light reflected from the cavity is modulated at that same frequency, and can be readily measured. The resonant frequency of the mechanical element is responsive to the environmental parameter to be measured, either by direct influence on the vibration of the mechanical element, or by means of the element's temperature change as a result of exposure to the environmental parameter.