Polarization-diversity Loop Structure Research Articles

Simultaneous OSNR Monitoring for Two Polarization Tributaries of a PDM Signal Using a Polarization-Diversity Nonlinear Loop Mirror Based on FWM

We investigate and experimentally demonstrate an optical signal-to-noise ratio (OSNR) monitoring technique for polarization-division-multiplexed return-to-zero ON-OFF keying (PDM-RZ-OOK) and differential-phase-shift-keying (PDM-RZ-DPSK) signals. Both polarization tributaries of the PDM channel can be simultaneously monitored based on cascaded four-wave mixing in a polarization-diversity nonlinear loop mirror. The interchannel crosstalk induced by nonlinear polarization scattering could be mitigated using the polarization diversity loop structure. As OSNR varies between 5 and 20 dB, the output power of the monitor has a dynamic range of 4.2 and 4.6 dB for the OOK and DPSK signals, respectively. We also demonstrate that the performances of the monitor are the same for both time-interleaved and synchronized PDM-RZ signals.

Current-Controlled Tunable Fiber Multiwavelength Filter Based on Polarization-Diversity Loop Structure

In this paper we have demonstrated absolute wavelength tuning in an optical fiber multiwavelength filter based on a polarization-diversity loop structure by controlling electrical currents injected into enameled wires wound on polarization-maintaining fibers (PMFs), that is, adjusting Joule heat generated from current-flowing enameled wires. The proposed filter consists of a four-port polarization beam splitter, a half-wave plate, a quarter-wave plate, and PMFs. The wavelength shifts of spectral dips in the transmission spectra of the fabricated filter were investigated with the variation of the injection current. The absolute wavelength of the filter could be controlled in proportion to the square of the injection current with considerably good linearity, and the wavelength tuning sensitivity was evaluated as ∼83.5 nm/A2 with respect to the injection current.

Current-Controlled Tunable Fiber Multiwavelength Filter Based on Polarization-Diversity Loop Structure

Current-Controlled Tunable Fiber Multiwavelength Filter Based on Polarization-Diversity Loop Structure

Inline Conversion Between Transmission and Reflection Spectra of Fiber Bragg Grating Using Polarization-Diversity Loop Structure

By incorporating a polarization-diversity loop structure, we have demonstrated an inline conversion between transmission and reflection spectra of a fiber Bragg grating (FBG) without reconfiguration of the filter structure containing the FBG. The proposed apparatus consists of a polarization beam splitter, an FBG, and two quarter-wave plates (QWPs). Without requiring rearrangement of input/output ports or additional optical switches, the spectral switching operation of the FBG was carried out through proper adjustment of the QWPs contained in the proposed filter.