Tunable Polarization Mode Dispersion Compensator Research Articles

Dual-core photonic crystal fibers for tunable polarization mode dispersion compensation

A novel type of dual concentric core photonic crystal fiber (PCF) is proposed and theoretically analyzed, aiming at the design of tunable dispersive fiber elements for polarization-mode-dispersion (PMD) compensation. The adjustment of the fiber's geometrical birefringence through the proper selection of structural parameters leads to very high values of differential group-delay (DGD). Moreover, the value of DGD can be dynamically tuned by infiltrating the outer core capillaries of the PCF with an optical liquid, which allows for the thermal control of its refractive index. Such fibers are envisaged as tunable dispersive fiber elements for PMD compensation or emulation modules.

Search Control Algorithm Based on Random Step Size Hill-Climbing Method for Adaptive PMD Compensation

Adaptive polarization mode dispersion (PMD) compensation is required for the speed-up and advancement of the present optical communications. The combination of a tunable PMD compensator and its adaptive control method achieves adaptive PMD compensation. In this paper, we report an effective search control algorithm for the feedback control of the PMD compensator. The algorithm is based on the hill-climbing method. However, the step size changes randomly to prevent the convergence from being trapped at a local maximum or a flat, unlike the conventional hill-climbing method. The randomness depends on the Gaussian probability density functions. We conducted transmission simulations at 160 Gb/s and the results show that the proposed method provides more optimal compensator control than the conventional hill-climbing method.

Tunable PMD compensator based on highbirefringence

The simple structure of a tunable polarization mode dispersion (PMD) compensator based on a cantilever beam and a high-birefringence linearly chirped fiber Bragg grating is proposed. A cantilever structure is used to introduce a linear strain gradient on the grating, and we can tune the compensated differential group delay (DGD) at a fixed signal wavelength just by changing the displacement at the free end of the beam. Based on numerical simulations, the performance of the cantilever structure as a PMD compensator is assessed for 10-Gbits/s nonreturn-to-zero transmission systems with a large DGD. With this compensator, a significant improvement of system performance can be achieved in the eye pattern of a received signal.

A novel tunable PMD compensation using linearly chirped fiber Bragg grating

We proposed a novel solution for polarization mode dispersion (PMD) compensation by applying transverse and uniform distributed force on a linearly chirped fiber Bragg grating . The compensated differential group delay (DGD) is tunable by changing the applied load at a fixed signal wavelength. Based on numerical simulations, the efficiency of this PMD compensator is assessed for the 10 Gb/s NRZ transmission system with 58.6 and 106 ps DGD, respectively. With this compensator, a significant improvement can be achieved in the eye pattern of the received signal.

Adjustable compensation of polarization mode dispersion using a high-birefringence nonlinearly chirped fiber Bragg grating

We demonstrate an adjustable polarization-mode-dispersion (PMD) compensator. The device uses a nonlinearly chirped fiber Bragg grating written into a high-birefringence photosensitive fiber. By mechanically stretching the grating, the device generates a time delay between different polarizations that is adjustable from 100 to 320 ps and is tunable over 2.3 nm. We demonstrate tunable PMD compensation of a 10-Gb/s signal that has an initial delay between the two polarization states of 127 or 302 ps.