Phase-squeezing properties of non-degenerate PSAs using PPLN waveguides

Abstract

We investigate the phase squeezing characteristics of non-degenerate phase-sensitive-amplifiers (PSAs) based on periodically-poled-lithium-niobate (PPLN) waveguides. We implement two PSA configurations with phase insensitive idler generation performed in both highly-non-linear-fiber (HNLF) and PPLN waveguides. In both cases we demonstrate regeneration of a noisy BPSK signal, despite net signal attenuation in the phase sensitive PPLN, and show that the level of phase squeezing varies with the phase sensitive dynamic range (PSDR). We observe that weak idler generation in the PPLN limits the achievable PSDR and that use of HNLF for idler generation leads to the largest PSDR. However, in phase regeneration measurements we observe that the pump phase modulation, required to overcome stimulated Brillouin scattering, adds significant amplitude noise, which increases with the PSDR.

All-Optical Regeneration of Phase Encoded Signals

“…difference frequency generation. The application of cascaded quadratic nonlinear processes offers a number of potential advantages, such as broadband operation, low-latency, no intrinsic frequency chirp and SBS resilience [93][94][95][96][97][98][99][100]. However, such devices are ultimately limited by power transfer to the third harmonic wavelength, infrared absorption and subsequent temperature instability.…”

“…A nondegenerate PSA was demonstrated in a PPLN waveguide using cascaded quadratic nonlinearities in [93]. Subsequently, this concept was also employed in [95] to demonstrate squeezing of the phase noise of a DPSK signal (Figure 34). Interestingly, this demonstration also considered the generation of the phase-locked signal-idler pair in a second PPLN waveguide, further miniaturizing the system.…”

Optical signal to noise ratio improvement through unbalanced noise beating in phase-sensitive parametric amplifiers

“…The fundamental principle behind PSA's NF of 0 dB is the coherent beating of the signal with a correlated copy of itself. PSAs have been successfully demonstrated both in second order (χ 2 ) nonlinear media and in third order (χ 3 ) nonlinear media [4][5][6][7] and employed in wide range of applications like signal phase regeneration [8], low noise amplification [9], imaging [10] etc. In χ 3 media such as optical fibers, a PSA can be realized by cascading two fiber optical parametric amplifiers (FOPAs).…”

Experimental Demonstration of Phase Sensitive Parametric Processes in a Nano-Engineered Silicon Waveguide

“…Phase-sensitive parametric processes have recently been the object of a renewed interest, resulting in the demonstration of novel signal processing applications such as phase regeneration [4]. Phase-sensitive signal processing functionalities have also been demonstrated in semiconductor optical amplifiers [5] and in periodically-poled lithium-niobate waveguides [6]. Being able to realize phase-sensitive processing in SOI waveguides would allow a wealth of new applications on this versatile platform.…”