Solution R=cos(√K2+2-)+~ sin(√K2+82z) K2+δ iK sin(√K2+62z) K2+6
Solution sin( ) cos( ) sin( ) 2 2 2 2 2 2 2 2 2 2 K z K j K S K z K j R K z d d d d d d + + = - + + = + +
Mode coupling between two fibres δ=0,R2(z)=cos2(Kz) 2D S(z=sin(Kz) ° coupling length 2D o=/2K Coupling coefficient 4ka Ka=K -a(d-2D) 12 21 β(1+aD(kx+a2) k2=n2k2-B2;a2=B2-n2k
Mode coupling between two fibres d=0，R2 (z)=cos2 (Kz) S 2 (z)=sin2 (Kz) • coupling length ： L0 =p/2K • Coupling coefficient ： 2 0 2 2 2 2 2 2 0 2 1 2 1 ( 2 ) 2 2 1 2 2 1 1 2 2 1 ; (1 )( ) 4 k n k n k e D k k K K x d D x x = - = - + + = = - - b b b 2D 2D d n2 n1 n2 n1 n2