Optical Phase Quantizer Based on Phase Sensitive Four Wave Mixing at Low Nonlinear Phase Shifts

Abstract

We propose and demonstrate a new phasesensitive (PS) scheme based on four-wave mixing followed by a polarizer to achieve an ideal binary step-like phase transfer function at nonlinear phase shifts as low as 0.3 rad by significantly increasing the parametric deamplification component. PS operation is obtained by polarization mixing the phase-locked and orthogonally polarized signal and idler, which is generated in a degenerate dual-pump vector parametric amplifier.Index Terms-Four wave mixing, nonlinear optics, phase sensitive amplifiers.

Polarization-Assisted Phase-Sensitive Processor

“…PSERs of about 2.5 dB and 5.6 dB were measured when our set-up was modified to operate as either a vector PSA or a scalar PSA respectively, and while maintaining the same total power of 20 dBm (all schemes were based on dual-pump degenerate FWM). A detailed description of how the experimental set-up was modified and the comparison in terms of PSERs as a function of total input power among the various implemented PSA schemes was discussed and reported in [20]. The signal was then assessed using homodyne coherent detection followed by real time data analysis (optical modulation analyser, OMA).…”

“…Some processing applications that have already been demonstrated include wavelength conversion [1][2][3][4][5][6][7], phase regeneration [8][9][10][11][12][13], electric field decomposition of phase shift keying (PSK) signals [14][15][16] and analogue-to-digital conversion (ADC) [17]. Single-and dual-pump configurations with the signal, idler and pump(s) being aligned either along the same polarization axis (scalar schemes) or on different polarization axes (vector schemes) and either non-degenerate or degenerate configurations (with the signal and idler being at either different or the same frequency, respectively) have been demonstrated [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In many of the applications above, for example, both PSA-based regeneration of BPSK signals and electric field decomposition of, in principle, any advanced modulation format require an ideal binary step-like phase response.…”

“…Alternatively, one may utilize the polarization dimension, e.g., we have recently demonstrated a PSA scheme that uses polarization mixing of a phase-locked signal-idler pair in a degenerate fiber optic parametric amplifier with two orthogonally polarised pumps and which we refer to as polarization-assisted PSA. Using this scheme an asymmetric PSER of ~26 dB (and thereby almost ideal binary step-like phase response) at NPSs as low as 0.3 rad was demonstrated [20]. Moreover, as the pumps in the PA-PSA are orthogonally polarized, the strength of the undesired FWM interaction between them is drastically reduced (a reduction of 30 dB relative to a scalar PSA was observed for a total launched power into the HNLF of 20 dBm), thereby substantially reducing the optical bandwidth occupied by the PA-PSA relative to the scalar case.…”

Quadrature demultiplexing using a degenerate vector parametric amplifier

“…However, the loss of the total scheme (degenerate vector FOPA and polarizer) would be in the order of |ν| in this case. A similar concept, using a vector FOPA followed by a polarizer, was also investigated in order to achieve phase squeezing with low pump powers [15]. The polarization axes with I and Q information are orthogonal in the limit |μ|, |ν| >> 1 since P I · P Q = |ν| 2 −|μ| 2 |μ| 2 +|ν| 2 = −1 |μ| 2 +|ν| 2 approaches zero with high parametric gain.…”

Multi-Channel Phase Regenerator Based on Polarization-Assisted Phase-Sensitive Amplification

“…Recently we have demonstrated a Polarization-Assisted PSA (PA-PSA) scheme, based on such a vector configuration, that exhibits a high asymmetric phase sensitive extinction ratio (PSER), defined as the difference between the maximum phase sensitive (PS) -gain and the maximum PSdeamplification, at modest pump powers [13]. It was used to demonstrate phase regeneration of single channel BPSK and QPSK signals [14].…”