In-line polarization-dependent microfiber interferometers and their applications in UWB signal generation

A novel in-line polarization-dependent microfiber interferometer (PD-MFI) is proposed and experimentally demonstrated, which is tapered from a commercial polarization-maintaining fiber. Different from conventional MFIs, the transmission spectra of such MFIs are highly polarization-dependent, due to the mode-sensitive birefringence. The experimental results agree well with the theoretical predictions. Moreover, exploiting the polarization-dependent property of PD-MFIs, we demonstrate a simple and flexible scheme of generating polarity-switchable ultra-wideband pulses in the optical domain. Doublet pulses with a central frequency of 6.28 GHz and a 10-dB bandwidth of 7.86 GHz are obtained. Hence, with the advantages of being fiberized, simple fabrication and robustness, these PD-MFIs can be attractive elements in optical signal processing, optical sensing, optical fiber communication, and microwave photonics.