Looped Polarization-Insensitive Fiber Optical Parametric Amplifiers for Broadband High Gain Applications

Vladimir Gordienko,Nick J Doran,Chandra B Gaur,Filipe M Ferreira

doi:10.1109/jlt.2021.3099441

Abstract

We investigate polarization insensitive fiber optical parametric amplifiers (FOPAs) employing a balanced polarization diversity loop with at least two unidirectional gain fibers. We describe and compare three variants of looped polarization insensitive FOPAs optimized for noise figure, mitigation of nonlinear impairments and their trade-off, respectively. The test scenario consists of amplifying, by up to 14 dB, a set of 21 × 50 GHz-spaced channels including a 35 GBaud PDM-QPSK signal, and evaluating a power of nonlinear crosstalk, noise figure and amplified signal BER for each variant. For the first time we demonstrate a polarization insensitive FOPA amplifying WDM signals with a noise figure as low as 5.8 dB, and a polarization insensitive FOPA with output WDM signal power of 23 dBm. The testing results let us identify likely application scenarios for each looped FOPA variant. We justify potential implementation of polarization-insensitive FOPAs in future optical communication systems by arguing its ability to deliver low noise figure <6 dB for output signal power as high as 29 dBm and to enable polarization insensitive gain for the most prominent single-polarization FOPA achievements realizing ultrawide high gain.

Highlights

FIBER optical parametric amplifiers (FOPAs) have the potential to play an important role in future optical communications by surpassing limits associated with fiberdoped amplification
Net gain of all channels was found using optical power spectra measured at the input and the output of polarization insensitive (PI)-FOPA and shown at Fig. 5(a)
The polarization dependent gain (PDG) of all channels was found using the optical power spectra of the two signal components at the input and the output of the loop. They were measured via a pair of calibrated bidirectional 1% tap couplers connected to the polarization beam splitter (PBS) in the loop (Fig. 1(a-c))

Summary

Introduction

FIBER optical parametric amplifiers (FOPAs) have the potential to play an important role in future optical communications by surpassing limits associated with fiberdoped amplification. FOPA allows for an ultimate wavelength flexibility highly beneficial for emerging ultra-wideband optical communications [1]. FOPAs can operate in arbitrary wavelength range [2], and its operation across O, E, S, C, and L bands and beyond has already been demonstrated [3]–[6]. FOPA can provide a virtually unconstrained gain bandwidth [2] with experimental demonstrations reaching 270 nm [7]. An exclusive ability of parametric amplifiers (including FOPA) is phase-sensitive amplification [8]. It allows for noise figure approaching 0 dB [9] and can double sensitivity (or capacity) of low SNR links [10] or significantly increase a fiber optic link reach, e.g

Methods

Results

Conclusion