H(x,1)=∑①()e 2ink,x in≈J1en1+J①n+J1e①n J=a∫E(x)b'=01 When there is an intensity difference of two optical fieldsWhen there is an intensity difference of two optical fields 2 ( , ) ( ) L ink x n n  =  x t t e  1 1 0 1 1 i t i t n n n n i J e J J e   − + −    +  +  + − − 2 2 ' ( ', ) ' 0, 1 L i lk x l J E x t e dx l = =   