Polarisation transformer on Ti:LiNbO ₃ with reset-free optical operation for heterodyne/homodyne receivers

Fundamentals of Bidirectional Transmission over a Single Optical Fibre

“…Here we used RyhPoult)=p~> E(RyhPou 1 (t-7))= 1 hp 1 and E(cos 2 (1/l))= 1 h. Notice that bere implicitly Gaussian interferometric noise is assumed, since the two noise terms are directly added (see discussion above}. Now the BER is written as Por moderate penalties, the BER will be dominated by the second term in (57). The penalty is calculated from the required increase of the optica!…”

“…The mixing efficiency of two counterpropagating (~) signals with a state of polarisation §p and !. is thus given by (57) The mixing efficiencies of identically-and orthogonally-polarised pump and probe wave are respectively (58) For fibres without birefringence (or only circular birefringence) and linear pump polarisation state (s 3 =0) the mixing efficiency is 1 for identical and 0 for orthogonal states of polarisation. (59) For fibres with linear birefringence and a linear input state of polarisation at 45 o, as in [3.43], s 3 =cos(</>), where </> is the optical phase difference between the fast and the slow axis, which increases linearly with the fibre length.…”

Lithium niobate integrated optics

“…A lot of the initial work had been camed out on X-cut, Y-propagating material, to make use of the r3, coefficient (see Alferness and Buhl 1985), but this is also the most susceptible geometry to temperature-induced instabilities caused by the high birefringence. Heidrich et al (1987) refined this by moving to X-cut, 2-propagating, improving temperature stability by having TE and TM modes each oriented parallel to an ordinary axis thus cancelling the natural birefringence, and allowing each mode to propagate with approximately equal velocity. This work also invoked the Poincare sphere to explain the transforming action of the device, and in operation was shown to be reset-free, a troublesome issue analogous to the phase-shift limitation on singleelectrode devices raised above.…”

Effect of fiber and solenoid variation parameters on the elements of a corrector PID for electromagnetic fiber squeezer based polarization controller

“…Temperature variations and mechanical disturbances further exacerbate the problem of achieving a desired SOP at the fiber output in the abovementioned applications. To solve this problem, several techniques have been proposed, such as polarization control [2,3], polarization diversity [4], polarization scrambling [5], and polarization switching [6]. Several technologies to realize polarization controller were introduced in the last two decades such as: mechanically rotating crystal wave plates or fiber loops, fiber squeezers or quartz with piezo electric elements [7], rotating wave plates [8,9], variable retarder plates [10], liquid crystals [11], and waveguide devices such as LiNbO3 [9,12].…”