Up to 427 GHz All Optical Frequency Down-Conversion Clock Recovery Based on Quantum-Dash Fabry–Perot Mode-Locked Laser

This paper reports on all optical frequency down conversion clock recovery based on Quantum-Dash Fabry-Perot mode-locked laser diode (QD-MLLD). A first section is dedicated to the generation of a tunable repetition rate pulse source based on a first QD-MLLD. The principle is to select three lines in the QD-MLLD spectrum with a filtering technique; the lines spacing are properly chosen to generate the desired repetition rate. In this paper, a frequency of 427 GHz was reached and observed with an optical sampling oscilloscope. Moreover, an encoded 170.8 GHz pulse source was characterized showing no penalty in comparison with our reference obtained by Optical Time Division Multiplexing (OTDM), which confirms the quality of the optical clock. In a second section, we show a clock frequency down conversion based on a second QD-MLLD, which is optically injected by a pulse source, whose repetition rate is 10 times higher than its self pulsating frequency. The 42.7 GHz down converted clock is then encoded and analyzed showing no penalty in comparison to a standard 42.7 Gbit/s reference, demonstrating its quality. Finally, in a third section, we demonstrate sub-harmonic clock recovery with a QD-MLLD, when a data stream is injected. We measure a penalty of 0.3 dB when compared to a standard 42.7 Gbit/s reference.