Abstract
A small displacement sensor in a coupled-cavity laser configuration formed with amoving extemal mirror ispresented to dynamically measure small forces. The sensor provides high sensitivity with a minimum detectable displacement of 0.8 nm independently of the lasing wavelength, while the lasingstate is mechanically stabilized by anegative feedback loop to maintain a constant external cavity length. We show that this sensor is of great use fordetecting extremely small distortion of a stiff cantilever, reflecting transient variations of small friction forces in mechanical systems.
