All optical clock recovery for 40 Gbaud NRZ QPSK signals using amplif ied feedba

An all-optical clock recovery scheme based on monolithic amplified feedback DFB laser (AFL) diode is proposed for nonreturn-to-zero (NRZ) quadrature phase shift keying (QPSK) format signals. By using a preprocessing stage, clock recovery (CR) is successfully demonstrated for 40-Gbaud NRZ-QPSK signal