Phase-sensitive amplification in a single bi-directional PPLN waveguide

Abstract

We investigate phase-sensitive amplification (PSA) and phase regeneration of a binary phase-shift keying (BPSK) signal using a single periodically poled lithium niobate (PPLN) waveguide. The PPLN is operated bi-directionally in order to simultaneously achieve phase correlated signals and phase-sensitive (PS) operation. We use injection-locking for carrier phase recovery and a lead zirconate titanate (PZT) fiber stretcher to correct path length deviations in the in-line phase regenerator. We observe a trade-off between high PS gain provided by high pumping power and stability of the device.

PPLN-based all-optical signal processing and phase-sensitive amplification

“…One of the major problems of PPLN-PSAs for optical amplification is the modest gain values, even at high pumping power. Using a PPLN waveguide with a conversion efficiency of ~400%/W and high pumping power (~27 dBm), we obtained gain values below 4 dB [18]. However, gain values of more than 10 dB have been reported in PPLN ridge waveguides [11].…”

“…In this sense, we proposed using bi-directional propagation in a single PPLN waveguide (Fig. 2), in which the copier and PSA stages are performed in opposite directions of propagation in the same device in order to reduce the number of devices and temperature controllers [18]. However, high pumping power on both propagation directions caused intense photorefractive effects that affected the stability of the phase-locked loop used to control the relative phase drifts between the interacting waves.…”

“…The recent advances in PPLN production technology have allowed obtaining devices with very high efficiency [11], and with low propagation losses [18], but further developments are still required in order to achieve performances equivalent to those of fiber-based PSAs. Sensitivity to the polarization state is also a big challenge that needs to be addressed in both fiberand PPLN-based PSAs.…”

Experimental investigation of phase-sensitive amplification of data signals in a four-mode fiber-based PSA

“…Periodically, poled lithium niobate waveguides [5], and especially fiber-optic parametric amplifiers (FOPAs) built with HNLFs [2][3][4]6], are the most common examples of such devices.…”