Record bandwidth waveband-shift-free optical phase conjugation in nonlinear fiber optical loop mirror

We present a novel configuration for broadband, wavelength-shift-free optical phase conjugation (OPC) utilizing four-wave mixing in a nonlinear fiber optical loop mirror (NOLM). In the proposed configuration, the input signals and the pump wave return to the input port of the NOLM whereas the phase-conjugated signals generated in the NOLM loop are transmitted through the output port. This allows the phase-conjugated copies to occupy the same wavelength band as the input signals, in line with the requirements for practical deployment of OPC in communication links. The demultiplexing of the phase conjugates from the input signals sharing the same band is achieved by imparting an asymmetric phase shift on the pump via a fiber Bragg grating. We experimentally demonstrate waveband-shift-free OPC with an extinction ratio between signals and conjugated copies at the NOLM output of 17 dB to 25 dB across a band of 35 nm. Whilst a 7-nm wide performance gap exists in the middle of the band, this is the record bandwidth for waveband-shift-free OPC in an all-fiber setup. We compare the experimental results with numerical simulations of the OPC-NOLM, identify the reason for the observed performance gap, and justify the route for further performance improvement

Recent advances in fiber optical parametric amplifiers for optical communications

We review our recent advances in fiber optical parametric amplifiers: demonstrate Mach-Zehnder architecture for polarization-insensitive operation with improved noise figure and reduced nonlinear crosstalk, show reduction of signal penalties due to pump phase modulation, and demonstrate waveband-shift-free optical phase conjugation in a nonlinear optical loop mirror

Waveband-shift-free optical phase conjugation in fiber loop mirror across 35-nm bandwidth

We experimentally demonstrate waveband-shift-free optical phase conjugation across the full C-band by employing a nonlinear optical loop mirror to demultiplex signals and phase-conjugated copies with an extinction ratio of at least 17dB across 35nm