a transducer is disclosed in which energy received from either mechanical or acoustic sources is converted into modulated optical power . the transducer is comprised of three basic components , an input optical fiber , an output optical fiber and a means for varying the optical coupling coefficient between the two fibers in response to information containing energy received from a mechanical or acoustic source . the input optical fiber carries a steady state optical signal which may be either continuous or pulsed . the means operates to control the coupling of the steady state optical signal into the output optical fiber . an intensity modulated output signal is then carried by the output optical fiber away from the transducer . the intensity modulated output signal may be either detected and thereby converted to electrical energy for transmission or may be transmitted in an optical form if optical communications facilities are available .