Optically Tunable Polarization State of Propagating Light at 1550 nm in an Etched Single-Mode Fiber With Azo-Polymer Overlay

An optically tunable and rotatable polarization state of light at 1550 nm is achieved in an etched single-mode fiber (SMF) with azo-polymer overlay. The SMF is etched by hydrofluoric acid to access the evanescent field, and then immobilized by the azo-polymer. With irradiation of 435-nm polarized light, photoinduced orientation of the azo-polymer occurs, causing birefringence in the fiber, and finally makes the polarization state of the 1550-nm propagating light tunable. Changing the polarization directions of 435-nm polarized lights, the polarization state of 1550-nm propagating light is tuned from right-handed elliptically polarized light to left-handed elliptically polarized light.