Experimental demonstration of an all-fiber endless polarization controller based on Faraday rotation

An all-fiber device for the control of the state of polarization (SOP) is presented. The controller is high speed (its time response is less than 50 ms in the worst case), low loss (insertion losses are 2.5 dB independently of the input SOP), and low cost (is constructed with standard single-mode fiber). The polarization controller has been implemented using two Faraday rotators and works at 1550 nm. We have also designed an algorithm that confers an endless performance to the device. The controller has been included in a 2.5 Gb/s CPFSK optical coherent system and results are presented here.