A new automatic alignment technology for single mode fi- ber-waveguide based on improved genetic algorithm * ZHENG Yu( ) , CHEN Zhuang-zhuang( ) , LI Ya-juan( ) ** , and DUAN Ji-an( ) Key Laboratory of Design for Modern Complex Equipment and Extreme Manufacturing, Ministry of Education of China, Central South University, Changsha 410083, China (Received 19 December 2008) A novel automatic alignment algorithm of single mode fiber-waveguide based on improved genetic algorithm is proposed. The genetic searching is based on the dynamic crossover operator and the adaptive mutation operator to solve the premature convergence of simple genetic algorithm. The improved genetic algorithm combines with hill-climbing method and pattern searching algorithm, to solve low precision of simple genetic algorithm in later searching. The simulation results indicate that the improved genetic algorithm can rise the alignment precision and reach the coupling loss of 0.01 dB when platform moves near 207 space points averagely. Document code: A Article ID: 1673-1905(2009)03-0165-4 DOI 10.1007/s11801-009-8131-x OPTOELECTRONICS LETTERS Vol.5 No.3, 1 May 2009 The packaging process of arrayed optical waveguides remains a bottleneck for the cost-effective fabrication of arrayed waveguide devices [1,2] . The power loss of packaging of the next generation arrayed waveguide should be less than 0.15 dB, it is to say that the alignment error between waveguide and fiber must be less than 1 μm [3] , and the connection precission between arrayed fiber and arrayed waveguide re- quires sub-micron precision. Therefore, alignment of fiber to planar waveguide chip is very critical in arrayed waveguide packaging because the coupling efficiency of optical mode fields transmitted between single mode fiber and planar waveguide depends on their optical alignment. The coupling scheme considered in this paper is shown in Fig.1, where the offsets in the transverse (X, Y) directions are dx and dy respectively, the offset in the direction of opti- cal axis is dz, and the angle misalignments are a, b and q respectively. The coupling efficiency can be affected with changing the dislocations in any direction. The coupling efficiency h may be computed by deter- mining the overlap integral of the optical field distributions in a reference plane [4,5] as shown in Fig.2, which is described as, * This work has been supported by Major Program of National Natural Science Foundation of China (No. 50735007) and National 863 Plan Projects(No. 2007AA04Z344) ** E-mail: liyajuan2002@126.com Fig.1 The coupling scheme between single mode fiber and planar waveguide , (1) where Y W is the fundament mode in the planar waveguide, Y F is the fundament mode in the optical fiber, and A is the integral area of overlap between two optical field distributions. Fig.2 The schematics of the optical field overlap A A A A A A d d | d | * W W * F F 2 * W F y y y y y y h ∫ ∫ ∫ =