QPSK 3R regenerator using a phase sensitive amplifier

Abstract

A black box phase sensitive amplifier based 3R regeneration scheme is proposed for non-return to zero quadrature phase shift keyed formatted signals. Performance improvements of more than 2 dB are achieved at the presence of input phase distortion.

Cascaded Nonlinear-Optical Loop Mirror-Based All-Optical PAM Regenerator

“…The 2 × 2 optical coupler (OC) divides the input optical field into two beams, which propagate in forward (E (1) f ) and backward (E (1) b ) directions, respectively. The optical fields after the HNLF, E (2) f and E (2) b , interfere at a 2 × 2 optical coupler, resulting into the optical transmitted field E out and the reflected field E r . In the HNLF, the SPM and cross-phase modulation (XPM) effects occur contributing to the nonlinear phase shift of the counter-propagating fields [14,15], and the former effect is involved in the following discussion, performing the SPM-NOLM.…”

“…f and E (2) b at the OC, the transmitted and reflected optical fields for a single NOLM can be expressed by:…”

“…where 2 . Furthermore, we normalize the nonlinear power transferring relation by using the normalized input power x = |E in | 2 /P 0 , x = |E in | 2 /P 0 and the normalized output power y = p out = |E out | 2 /(G 0 P 0 ):…”

“…, where f 1,2 (x) and g d (1,2) (x) correspond to the results from the first and second NOLMs. Obviously, the most straightforward approach to g d (x l ) → 0 is to optimize the NDG of the first NOLM stage g d (1) (x), and to set its optimal WP at a higher regenerative level in view of the oscillation properties of the NPTF curve.…”

“…All-optical signal processing is a promising technology to directly deal with these high-spectra-efficiency signals in the optical domain, bypassing the so-called "electronic bottleneck". In particular, optical signal regeneration also evolves from the traditional optical-electrical-optical (O/E/O) approach to the all-optical regeneration [1,2]. All-optical PAM regeneration technologies begin to attract more attention because of the widespread use of PAM signals in data centers [3] and the need for medium-or long-distance communication between data centers [4].…”