Vol. 45, Issue 3, pp. 419-428 (2015)

Abstract

There are several cases in which the measurement of light frequency changes is necessary. For example, it is noteworthy to define the stability of output frequency (wavelength) of a laser beam. Besides, high speed light frequency sensors can be used in optical frequency modulation which has advantages including low cost, high data rate and low noise modulation. Nowadays, for transmitting optical signals, the usual method is converting the message signal to a digital signal and transmitting it with a special digital modulation and after receiving, it will be converted to an analog signal. The mentioned sections are complex and expensive. Sending a digital signal (pulse) through a nonlinear optical medium (optical fiber) may cause undesirable effects such as generating harmonics and energy dispersion in the medium. In this case, we are able to send an analog message as an analog optical signal by a tunable laser diode and receive it by this sensor. Also transmitting digital signals with usual digital modulations such as frequency shift keying will be possible. In this work, we present a new differential light frequency sensor based on an integrated Michelson interferometer whose precision in detecting wavelength changes is less than 0.001 nm.