Multi-channel phase squeezing in a PPLN-PPLN PSA

All-Optical Regeneration of Phase Encoded Signals

“…For example, the addition of an extra signal on a device based on  (3) nonlinearities can affect its response by the onset of additional effects originating by either cross-phase modulation, four-wave mixing or even Raman scattering. These impairments are less severe in cases where the signals are only required to propagate in a linear fashion within the nonlinear medium and share a common pump [14], or where the nonlinearities are localized within a certain wavelength region [110]. However, even in these cases, the presence of multiple signals drawing simultaneously from the power of the same pump can give rise to crosstalk.…”

“…Despite this multi-channel PSA demonstrations based on a single pump non-degenerate parametric process have already been reported both in fibres and PPLN waveguides. In the PPLN-based demonstration reported in [110] one common pump was employed to effect phase squeezing of four independent channels through the use of cascaded quadratic nonlinearities. The experiment achieved squeezing of the standard deviation of the phase angle by up to 1.3 times, whereas the power of each of the four channels was ~15 dB weaker than the pump to ensure that the parasitic cross-talk components were weaker than 22 dB below the generated signal-idler pairs.…”

Investigation of an All-Optical Black-Box PPLN-PPLN BPSK Phase Regenerator

“…Previously, C-band PS behavior has been demonstrated in PPLN based PSAs both with degenerate signal, idler and pump in a ridge waveguides [4], where low noise amplification was also recently demonstrated [5], and in the WDM compatible, non-degenerate idler configuration [3], [6] where the phase sensitive dynamic range (PSDR) was shown to be the key parameter in determining the phase squeezing performance. Furthermore, phase squeezing of multiple signal channels has also been demonstrated [7] in a PPLN-PPLN PSA and it has been shown that intra-channel crosstalk has small impact on the phase squeezing performance, compared to the FWM-based crosstalk in FOPA PSAs. Here we investigate an all-optical, C-band, black-box phase regenerator for binary phase-shift keyed (BPSK) signals utilizing cascaded second order nonlinearities in PPLN waveguides for the first time.…”