In-line polarization-state converter

Abstract

The invention discloses an in-line polarization-state converter. In the polarization converter, a laser beam is radiated onto the side of a photosensitive optical fiber. The laser beam causes the refractive index of an optical fiber core to asymmetrically vary. Birefringence is induced in a core mode of the optical fiber by the variation in the asymmetrical refractive index. An optical fiber segment having the birefringence is generally disposed on a waveguide path of the optical fiber to change the polarization state of an optical signal passing through the optical fiber segment. That is, the phase of the optical signal passing through the optical fiber is changed by radiation of laser beams, which results in a variation in polarization state. The polarization converter disposed on the waveguide path is covered with a metal tube in order to prevent the polarization converter from being bent or broken. In addition, optical fiber connectors are provided at both ends of the polarization converter for easy connection.

1 . An in-line polarization-state converter comprising:
 optical fiber connector adapters that are fixed to a support panel; and   an optical fiber package that is connected to the optical fiber connectors and rotates to change the polarization state of light incident thereon,   wherein the optical fiber package includes an optical fiber segment whose refractive index is increased by irradiation with a laser beam, and   the optical fiber package changes the polarization state of incident light using the optical fiber segment.   
   
   
       2 . The in-line polarization-state converter according to  claim 1 ,
 wherein the optical fiber package includes:   the optical fiber segment whose refractive index is increased by irradiation with the laser beam;   a metal tube that is provided outside the optical fiber segment to protect the optical fiber segment; and   optical fiber ferrules each of which has fixing grooves and which are provided at both ends of the optical fiber segment in order to facilitate optical connection.   
   
   
       3 . The in-line polarization-state converter according to  claim 2 ,
 wherein the optical fiber package further includes:   a housing that covers the outside of the metal tube and has protruding portions fitted to the grooves of the optical fiber ferrules.   
   
   
       4 . The in-line polarization-state converter according to  claim 3 ,
 wherein the housing includes an upper housing and a lower housing that are separated from each other.   
   
   
       5 . The in-line polarization-state converter according to  claim 1 ,
 wherein the laser beam has a wavelength in the range of 100 nm to 350 nm, and   the laser beam is radiated onto the optical fiber to induce a chemical reaction in the optical fiber, thereby increasing a refractive index.   
   
   
       6 . The in-line polarization-state converter according to  claim 1 ,
 wherein the laser beam has a wavelength in the range of 500 nm to 1050 nm, and   the laser beam is radiated onto the optical fiber to induce a physical reaction in the optical fiber, thereby increasing a refractive index.