Uniform Polarization Scattering With Fiber-Coil-Based Polarization Controllers

Abstract

Abstract-A detailed study of fiber-coil-based polarization controllers (PCs) is performed. First, a method to deterministically calculate the PC configuration in order to transform between any two states of polarization is presented. In a second stage, the case in which the configuration angles are randomly changed is studied. The cases of a single PC and of the system obtained with the concatenation of several PCs are analyzed. For both cases, a general expression for the variance of the Stokes parameters is obtained. Using this expression, it is demonstrated that it is possible to achieve uniform polarization scattering using a concatenation of fiber-coil-based PCs. Finally, it is shown that fiber-coil-based PCs can be used to emulate both first-and second-order polarizationmode dispersions.

QBER Estimation in QKD Systems With Polarization Encoding

“…For high values of pulse rates the SOP at the PCD output will be close to the target value, i.e., , whereas for low rates the SOP will present a random value in the Poincaré sphere, i.e., [22]. Using (17) into (4) we obtain the following expression for the errors due to the imperfect operation of the feedback SOP control (18) The error probability given by (18), and illustrated in Fig.…”

“…Assuming a Gaussian pulse shape , then is given by (21) where is the half-width at -intensity of , which is related with the pulse full width at half maximum (FWHM) by . In order to account for the pulse broadening due to chromatic dispersion, we should replace in (21) by (22) where is the dispersion length [13]. Assuming, for instance, that data pulse is removed, then the total number of counts on the quantum data detector due to reference pulse leakage is given by (23) where is the click probability, and is given by (19).…”

Polarization Scattering Property of Cascaded Polarization Controllers

“…Previous results show that just one PC is clearly not enough to provide uniform SOP scatterings [2]. In order to enhance the SOP scattering, a concatenation of several PCs must be considered, as shown in Fig.…”

“…Indeed, some authors have proposed PMD emulators based on pieces of polarization maintaining fibers, interconnected with uniform polarization scattering devices [1]- [4]. In this context, fiber-coil-based polarization controllers (PCs) [2] can be used to scatter the state of polarization (SOP) over the Poincaré sphere [1], [2]. In [2], we presented a detailed study of polarization scattering using this kind of PC.…”

“…In this context, fiber-coil-based polarization controllers (PCs) [2] can be used to scatter the state of polarization (SOP) over the Poincaré sphere [1], [2]. In [2], we presented a detailed study of polarization scattering using this kind of PC. It was shown that using a concatenation of three PCs, and changing the waveplates of each PC following a uniform distribution between -π and π, a good uniform polarization scattering is achieved.…”