US 7,382,951 B2
Method for sequentially writing fiber Bragg grating by using real-time side-diffraction optical fiber position monitoring
Kuei-Chu Hsu, Yongkang (Taiwan); Lih-Gen Sheu, Xinwu Shiang (Taiwan); Kai-Ping Chuang, Pingtung (Taiwan); Shu-Hui Chang, Gangshan (Taiwan); and Yinchieh Lai, Taichung (Taiwan)
Assigned to National Chiao Tung University, Hsinchu (Taiwan)
Filed on Sep. 12, 2005, as Appl. No. 11/225,670.
Claims priority of application No. 94115916 A (TW), filed on May 17, 2005.
Prior Publication US 2006/0263007 A1, Nov. 23, 2006
Int. Cl. G02B 6/00 (2006.01); G02B 6/34 (2006.01)
U.S. Cl. 385—37 7 Claims
OG exemplary drawing
 
1. A method for fabricating a complex fiber Bragg grating by using UV sequential writing, characterized by probing another reference grating as a phase reference for each grating section writing, comprising the steps of:
(1) arranging a reference fiber Bragg grating and a waiting to be exposed optical fiber in parallel, the modulated amount of refractive index of the reference fiber Bragg grating is large and uniform;
(2) allowing a probe beam to be incident along the Bragg angle of the reference grating to form a first-order Bragg diffraction beam when the positioning point of each UV beam overlap exposures is determined, and generating an interference fringe by causing an interference between the first-order Bragg diffraction beam and another reference beam;
(3) after a translation stage (05) is shifted by a predetermined distance to around next positioning point, fine tuning the translation stage (05) to the final position of this positioning point by comparing the phase distributions of interference fringes before and after shifting the translation stage (05) by using a feedback system until phase distribution falls within a given error range;
(4) turning on a UV beam exposure shutter for a given exposure time and then turning off the shutter; and
(5) shifting the translation stage (05) to next positioning point, and repeating steps (3) and (4).