title: Optical pump phase locking to a carrier wave extracted from phase-conjugated twin waves for phase-sensitive optical amplifier repeaters.
abstract: In this paper, an optical phase-locked loop assisted by sum-frequency and second-harmonic generation (SS-OPLL) for frequency nondegenerate optical parametric phase-sensitive amplifier repeaters is experimentally demonstrated. First, theoretical derivations show that carrier extraction from phase-conjugated twin waves (PCTWs) and reference light generation are achieved by sum-frequency generation; therefore, the SS-OPLL circuit enables optical phase locking between PCTWs and a pump wave by a simple architecture based on a balanced OPLL. Then, optical phase locking between 20-Gbit/s quadrature phase-shift keying PCTWs and an individual pump source is experimentally demonstrated. Experimental results indicate that phase errors were reduced during the SS-OPLL operation.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Okamura
authors.forename: Masashi
authors.initials: M
authors.lastname: Abe
authors.forename: Kotaro
authors.initials: K
authors.lastname: Kondo
authors.forename: Yuya
authors.initials: Y
authors.lastname: Ohmichi
authors.forename: Takushi
authors.initials: T
authors.lastname: Kazama
authors.forename: Takeshi
authors.initials: T
authors.lastname: Umeki
authors.forename: Masafumi
authors.initials: M
authors.lastname: Koga
authors.forename: Atsushi
authors.initials: A
authors.lastname: Takada