Realization of broad-band phase devices by using W-type eccentric-core optical fibers

Axially nonsymmetric W-type optical fibers are proposed as broadband phase devices for optical-fiber systems to provide the Fresnel´s rhomb retarder in classical optical systems. Propagation characteristics of the W-type eccentric-core optical fibers are investigated theoretically using the boundary-integral method. The results of the numerical analysis indicate that such broadband phase devices can be realized by using the wavelength-dependent birefringence of axially nonsymmetric W-type optical fibers. It is theoretically found in the case of eccentric cores that a relative bandwidth of 18.2% with a phase retardation error of 2% is realizable without the propagation of higher-order mode waves