The invention is related to an optical waveguide device comprising

a length of fiber including a monomode core having a refraction index of n_co, a photosensitivity of S_co and a radius R_co

and an internal cladding with an refractive index of n_cl, a photosensitivity of S_cl and a radius of R_cl,

and a outer cladding surrounding the internal cladding with an refractive index that allows the existence of multiple cladding modes,

and a slanted Bragg grating with an effective tilt angle of written in core and inner cladding of the optical waveguide, coupling the fundamental mode into several cladding modes

where R_cl2.5 R_co and the S_coS_cl.