Multi-span transmission using phase and amplitude regeneration in PPLN-based PSA

Abstract

We demonstrated multi-span transmission using a periodically poled LiNbO(3) (PPLN) based phase sensitive amplifier (PSA). An in-line PSA with a carrier recovery and phase locking system is implemented as a repeater amplifier in a recirculating loop. We achieved a PSA gain as high as + 18 dB and a high external gain of + 12 dB for the in-line PSA as a black box. The impairments caused by phase noise resulting from fiber nonlinearity and intensity noise caused by the amplified spontaneous emission (ASE) of an optical amplifier are largely suppressed using the phase and amplitude regeneration capabilities of the PSA. The ultra long-haul transmission of a 28-Gb/s binary phase shift keying (BPSK) signal over 5400 km was achieved with phase and amplitude regeneration.

Design of multilevel amplitude regenerative system

“…All-optical regeneration offers an energyefficient solution for the removal of both deterministic and stochastic impairments, enabling high-capacity transmission [2][3][4][5][6][7][8]. A nonlinear optical loop mirror (NOLM) proposed in [9] was experimentally demonstrated as an efficient amplitude regenerator [4,[10][11][12], and its cascadability in long-haul transmission systems has been experimentally proved [2,5,13,14].…”

“…In particular, we further consider a phase quantizer based on a phasesensitive amplifier (PSA) placed after each amplitude regenerator. The TF of the M-level phase quantizer [20] (the cascadability of which was demonstrated in [8]) is given by P out p e iφ out P in p e iφ 1 me −iMφ :…”

Shannon Capacity of Nonlinear Communication Channels

“…A number of promising results were obtained for black-box WDM (62), 4-phase-shift keying (PSK) (63)-(65), 6-PSK (66), , and 16-quadrature amplitude modulation (QAM) (68), which prove the possibility to remove noise from both quadratures of the signal. Another important feature of regeneration is cascadability, as being placed in cascades along the line regeneration enables accumulation of noise squeezing effect and, as a results, improves the received signal (41,69,70,71). Thus, optical regeneration has been established as a promising and rapidly evolving area.…”

Optimal packing for cascaded regenerative transmission based on phase sensitive amplifiers

“…Mach-Zehnder [21][22] or non-linear loop mirrors (NOLMs) [24][25][26]. It has been shown [19], [24][25][26], [30] that most of them can support large regenerator cascades and bring significant improvements in the overall system capacity and transmission distance. However, they were primarily designed to address binary channels offering optimization only in the amplitude and pulse shape of the optical signal.…”

“…Due to this property PSA technology is compatible with a broader variety of signal constellations than binary ASK regenerators and can support the development of digital fiber links for long haul transmission at much higher spectral efficiencies. Recent experiments [30] have already demonstrated a cascadability of more than 100 PSA elements enabling transmission of BPSK signals over distance larger than 5000 km. For higher spectral efficiencies a careful selection of the modulation format is required, due to the strong interplay between the noise and the non-linear transfer function of the PSA, to improve the overall transmission performance beyond the limits of linear [31] and nonilnear optical channels [13], [7], [32].…”