Application of Quantum State Control to Optical Phase-Locked Loop

Yoshihiro YOSHIDA  Masao NAKAGAWA  Osamu HIROTA  

IEICE TRANSACTIONS (1976-1990)   Vol.E72   No.5   pp.539-546
Publication Date: 1989/05/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: Special Section PAPER (Special Issue on Information Theory and Its Applications)

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In optical coherent communications with homodyne detection system, it is one of the most essential problems to synchronize the phase of local oscillator with that of received signal on the receiver. In general, the phase-locking performance is limited by frequency fluctuation and quantum noise of light source. So far some optical phase-locked loops have been proposed in order to optimize phase-locking performance. Their main purpose is to minimize phase error variance of systems with frequency fluctuation and quantum noise transformed into the electric region. To improve the phase-locking performance under the same situations, this paper proposes a new optical phase-locked loop with received quantum state controller, called a Squeezed-PLL, which can reduce the impact of quantum noise in the optical region. This system can eliminate the effect of the vacuum noise due to the beam splitting. Finally, the general signal to noise ratio of data-branch is shown, and phase-locking performance of the Squeezed-PLL is verified by computer simulation.