Endless polarisation control using four fibre squeezers

Endless state-of-polarization control for coherent optical communication systems using nematic liquid crystals

“…A practical SOP controlling system must change the polarization endlessly to prevent momentary signal loss during the reset of any constituent components. Currently, various groups are testing systems which use mechanically induced birefringence as a means of matching the signal SOP to that of the LO [8]- [14]. Most other research has concentrated on the use of LiNiB03 waveguides [15]- [18], while other proposed systems utilize electrooptic crystals, Faraday rotators, or rotating wave-plates [19], [20].…”

“…Equation 2-7gives the baseband signal which is of no interest and will be be removed with a high pass filter. Equation (2)(3)(4)(5)(6)(7)(8) gives the signal of interest and has a carrier frequency of oco.…”

“…For the upper range reset, 0y = 1t -Cos-1 (cos"l'z/cos"l'z 0 ) which is ( 4-9) for 7t/2 S '¥ zo S 7t, and 0po = 7t/2. Using (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) for the negative argument in gives,…”

Polarization Recombining: A New Automatic Polarization Control Scheme for Heterodyne or Homodyne Optical Receivers

“…Different methods and techniques to overcome polarization-induced signal fading are being progressively developed and several reports have already been published [1][2][3][4][5][6][7][8][9]. These can be classified in three main categories [10] as:…”

Analysis of input-polarization-induced phase noise in interferometric fiber-optic sensors and its reduction using polarization scrambling

“…INTRODUCTION ENERALLY, in coherent optical fiber systems based G on conventional low-birefringence fiber and fiber components, such as coherent communications and interferometric fiber sensors, random fluctuations in the state of polarization (SOP) of the interfering beams guided in the nominally circular fiber core can lead to fading of the interference signal. This polarization-induced fading (PIF) phenomenon has led to significant research interest in the development of techniques to overcome the problem in both the communications [1]- [4] and sensor [5]- [ll] communities. Several schemes have been proposed to overcome PIF, ranging from the use of manual or automatic polarization controllers [1]- [4] to adjust the SOP of the interfering beams, polarization diversity detection schemes based on output polarization state selection [4], [ 7 ] , [8], or the use of high-birefringence (polarization preserving) fiber in the construction of the system.…”