All-optical wavelength migration and erasure via nonlinear polarization gating in a TiN/Ti3C2 heterojunction microfiber hybrid device

Conventional all-optical wavelength converters suffer from a fundamental limitation: the residual original signal remains at the output, resulting in spectral inefficiency and potential coherent crosstalk. Although nonlinear polarization rotation in fiber can, in principle, suppress the residual signal, it typically requires impractically long interaction lengths or high pump powers. Here, we address this limitation using a hybrid architecture that monolithically combines wavelength conversion and active signal erasure. In particular, a highly nonlinear fiber (HNLF) is used to generate a wavelength-converted idler via four-wave mixing, while a cascaded TiN/Ti3C2 heterojunction-coated microfiber (THM) operates as an ultra-compact Kerr gate to induce strong nonlinear polarization rotation on the original signal. An in-line polarizer (ILP) then selectively suppresses the polarization-rotated original signal while transmitting the idler. Using this functionally decoupled configuration, we experimentally realize a “wavelength cut-and-paste” operation with an original-signal suppression ratio of 20.8 dB and a conversion efficiency of −22.2 dB at 10 Gbaud/s. Clear eye diagrams confirm that the converted idler preserves acceptable signal integrity. In addition, the roles of the HNLF, THM, ILP, and optical bandpass filter, as well as the impact of insertion loss on system performance, are explicitly clarified. This work provides a practical route toward spectrally efficient and crosstalk-resilient all-optical signal processing for future elastic optical networks.