Interrogation of a fiber Fabry-Perot sensor by current modulation of a   diode laser
  We present a method for remote interrogation of passive fiber Bragg grating Fabry-Perot resonators, employing current modulation of the diode laser source. With the presence of both RF amplitude and frequency modulation, it is a variant of the ultra-sensitive Pound-Drever-Hall laser frequency locking technique. We demonstrate that current modulation and interferometric demodulation removes the need for a phase modulator in the sensing architecture. 
Jong H. Chow, Jeff S. Cumpston, Ian C.M. Littler, David E. McClelland,   Malcolm B. Gray