Apparatus for continuous polarization and phase control

Claim 1

An arrangement for continuous operation which does not require that the polarization and phase control be reset, comprising an optical waveguide (10) in which the propagation constant β 1 of a first optical wave (TE or TM mode) propagating in a defined direction (R) and the propagation constant β 2 of a second optical wave (TM mode or, respectively, TE-mode) propagating in the direction (R) and polarized orthogonally relative to said first wave differ from each other at a prescribed wavelength λ 0 , and comprising a plurality N=n×m of locations (F i , i=1,2, . . . , N) for modifying the polarization and phase, which are arranged in said direction (R) in a distance (S) which is divided into path sections (A k , k=1,2, . . . , m) of equal period lengths L, and are arranged at a distance following one another such that the same plurality N of locations (F i ) lie in each of the m sections (A k ) of the distance (S), whereby a fixed period length L is an integer multiple of a beat length Λ o of said waves at the prescribed wavelength λ o , and whereby the polarization and the phase of said waves are tunable at each location (F i ) for modifying polarization and phase, whereby the amount of the tuning of the polarization and the phase is defined by variable coupling factors χ i individually associated with each and every location (F i ) for modifying the polarization and phase, said coupling factor χ i defined by: χ.sub.i =χ.sub.o sin (η+α(i)) with i=1,2, . . . , N where χ o is a variable maximum value of the coupling factor χ i , η is a control variable which is variable at least in the range from 0 through 2π, and α(i) is a defined function dependent on the identifier i of the locations (F i ) for modifying the polarization and phase, characterized in that (a) a waveguide (10) is provided wherein a difference Δβ(λ) between the mutually different propagation constants β 1 and β 2 as well as the maximum value χ o which are functions of the wavelength λ are so small at the prescribed wavelength λ o that the beat length Λ o allocated to the wavelength λ o according to the relationship: Λ.sub.o =π/√(Δβ(λ.sub.o)/2).sup.2 +(χ.sub.o (λ.sub.o)).sup.2 is at least the hundred-fold multiple of the prescribed wavelength λ o ; (b) n=4 locations for modifying polarization and phase which are located in every section (A k ) of the distance (S); and in that (c) α(i)=(i-1)·π·Λ o /2·Λ 1 with i=1,2, . . . , N is selected whereby Λ 1 is a beat wavelength of said first and second optical waves which are polarized orthogonally relative to one another, said beat wavelength corresponding to an operating wavelength λ 1 according to the relationship: Λ.sub.1 =π/√(Δβ(λ.sub.i /2).sup.2 +(χ.sub.o (λ.sub.1)).sup.2, and said arrangement being operated at this operating wavelength λ 1 and wherein, Λ 1 is ordinarily unequal to the geometrically prescribed beat length Λ o , which predetermines the prescribed wavelength λ o , but can also be equal to Λ o whereby it is generally valid that Λ 1 ≠Λ o for λ 1 ≠λ o .