Byeong Ha LEE^*, Tae-Jung EOM, EunSeo CHOI, Gopinath MUDHANA and Changsu LEE¹

Department of Information and Communications, Kwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, Korea
¹The University of Suwon, Wau-ri, Bongdam-up, Whasung-shi, Kyunggi-do 445-743, Korea

(Received February 27, 2003; Accepted April 3, 2003)

A novel all-fiber optical delay line for an advanced optical coherence tomography (OCT) system is proposed. Using the distributed reflectance characteristic of a chirped fiber Bragg grating (CFBG), the optical delay can be obtained without leaving the fiber that forms the system. The proposed delay line consists of a pair of identical CFBGs. The gratings are cascaded in reverse order to cancel the inherent wavelength dependency of CFBGs. Tunable optical delay is obtained by applying small strain on one of the CFBGs through an attached piezo actuator. The small displacement induced by the piezo actuator is amplified by a factor of up to 100 due to the distributed reflectance characteristic of the CFBGs. This principle and characteristics of the proposed optical delay line are analyzed in detail.

Key words: delay line, fiber gratings, FBG, CFBG, OCT, tomography

^*E-mail address: leebh@kjist.ac.kr