Implementation of differential precoder for high-speed optical DQPSK modulation

The differential precoder is a key component for high-speed optical differential quadrature phase-shift keying (DQPSK) transmissions, and a method of the implementation of differential precoder for high-speed optical DQPSK modulation is introduced in this paper. This method first researches the optical DQPSK encoder and decoder, and then gets the function of the differential precoder. Depending on the karnaugh maps, we can deduce the logic operations of the differential precoder. Using this method, the logic operations of different DQPSK precoders can be deduced corresponding to different encoders and decoders.