Optical 8-ary phase shift keying modulation format generator based on three microring modulators

We have proposed an 8PSK modulator based on three microring modulators (MRM). The design consists of three MRMs, each with a radius of 11.1 mu m. Of these three, two MRMs are connected in parallel and they together generate a quadrature phase shift keying (QPSK) signal. While at the output port of the QPSK, a third MRM is connected in series works as an angle modulator, which is basically a 45 degrees phase shift modulator; that is, the output of the MRM varies by 45 degrees depending on the bit pattern fed to it, '0'or '1' respectively. We have simulated and shown the performance of the proposed 8PSK modulator after transmitting the modulated signal through various lengths of optical. Constellation diagrams and eye diagrams at different fiber lengths are analyzed. Bit error rate (BER) versus optical signal to noise ratio curve shows that, 10(-3) BER has been achieved at 13.5 dB optical signal to noise ratio.