Micro-structured optical fiber surface relief grating using azo polymer film S. Choi, K. R. Kim, and K. Oh Department of Information and Communications, K-JIST, 1 Oryong-dong, Buk-ku, Kwangju, 500-712, Rep. of Korea Tel: +82-62-970-2213, Fax: +82-62-970-2237, E-mail: koh@kjist.ac.kr C. M. Chun, M. J. Kim, S. J. Yoo, and D. Y. Kim Department of Material Science and Engineering, K-JIST, 1 Oryong-dong, Buk-ku, Kwangju, 500-712, Rep. of Korea Abstract: Fabrication of surface relief grating on the top of optical fiber core and its characterization are reported. Azo-polymer thin film layer on the surface has been patterned interferometrically to form one- and two-dimensional gratings. Diffracted beam pattern has been characterized. 2003 Optical Society of America OCIS codes: (230.4000) Microstructure fabrication; (230.1950) Diffraction gratings; With increasing demand on transforming optical beam shapes, investigations inscribing directly index modulation pattern on the fiber surface have been recently performed using femtosecond laser pulses[1,2]. Formation of these photorefractive index modulation structures can provide novel optical functions such as directional couplers and filters. However, the femtosecond pulse could easily induce surface damage and requires a sophisticated apparatus. Azo-polymer materials have been studied to effectively inscribe periodic structures on the deposited film. Compared to photoresist films, azo-polymer layers can produce surface-relief-grating (SRG), where the actual mass of layer is modulated rather than refractive index[3,4]. Their applications are being expanded to optical devices[5] and holographic data storages[6]. SRG process can provide advantages such as capability to superimpose multiple patterns, to directly inscribe patterns with flexible control of modulation period and depth. In this paper, we report a novel technique to directly inscribe SRG structures on the fiber-end-surface. The principles, fabrication procedures, and diffraction beam patterns in the 1-D and 2-D SRGs are discussed and experimentally measured. Fig.1. Experimental setup for SRGs on the fiber-end-surface. Single-mode-fiber was cleaved at 90 o and PDO3 polymer containing azobenzene group was solvated in cyclohexanone and then filtered 10wt% PDO3 solution was dropped on the fiber-end-surface. Thin film was formed by a spin-coating system and dried in a vacuum oven at 80 o C for 1-hour. Experimental setup to fabricate SRGs on the fiber-end-surface is shown in Fig.1. Ar-ion laser at 488 nm was used as an input signal. The laser beam was CTUJ1 CTUJ2 CTUJ3 CTUJ4 CTUJ5 CTUJ6 CTUK1 CTUK2 CTUK3 CTUK4 CTUK5 CTUK6 CTUL1 CTUL2 CTUL3