AN OPTICAL VOLTAGE CONTROLLED OSCILLATOR FOR AN OPTICAL PHASE LOCKED LOOP

摘要

An optical phase locked loop (1), comprising an optical phase detector (2) receiving as inputs an optical signal to be locked ( symbol I ) and a locked optical signal (symbol II ) and providing as its output an electrical error signal (VPD) indicating the phase shift existing between the optical signal to be locked (symbol I ) and the locked optical signal (symbol II ); an electrical loop filter (3) receiving the electrical error signal (VPD) and outputting a filtered electrical error signal (VPDF), and an optical voltage controlled oscillator (4) receiving as an input the filtered electrical error signal (VPDF) and outputting the locked optical signal (symbol II ). The optical voltage controlled oscillator (4) comprises an electrical voltage controlled oscillator (8) receiving as an input the filtered electrical error signal (VPDF) and outputting a modulating electrical signal (VEVCO), an external-cavity semiconductor laser source (9) providing an optical carrier (Soc), and a Mach-Zehnder optical amplitude modulator (10) receiving as an input the optical carrier (Soc) and the modulating electrical signal (VEVCO) and outputting the locked optical signal (symbol II ), which is obtained by amplitude modulating the optical carrier (SOC) with the modulating electrical signal (VEVCO).