Optical fiber with distributed bend compensated filtering

A method, comprising:

• bending at least a portion of an optical fiber to have a substantially helical shape about a helical axis, the optical fiber having a core region having a longitudinal axis and a cladding region surrounding the core region, the longitudinal axis substantially tangential to a helical bend in the optical fiber, the core region and cladding region configured to support and guide the propagation of signal light in a fundamental transverse mode in the core region in the direction of the longitudinal axis, the fiber having a bend-induced gradient in its equivalent index of refraction over the portion of the core region, at least a portion of cladding region having a graded index of refraction opposite the bend-induced gradient of the mode,
• wherein the cladding region comprises an inner cladding region;
• and
• wherein the material index of refraction of the fiber as a function of radial position in a pre-compensated portion of the inner cladding region equals the mode effective index minus a compensation term.