The usage of optical coupler and its optimization signal in modified optical time domain reflectometer


  • Subramaniam Jahanadan
  • Yusof Munajat



Fiber Length, Attenuation, OTDR, Signal Optimization,


In this study, attention was made to measure the length of the fiber and the coefficient of the fiber attenuation utilizing novel configurations. Laser diode
source with a fundamental wavelength of (808 ± 10) nm with a maximum power of 50 mW was employed. First measurement utilizes a polarized beam
splitter whereas the second measurement utilizes a beam coupler. The laser was launched in pulsed mode with a 75 ns pulse width which delivered
approximately 15 mW power into the fiber and the laser source was adjusted to operate in continuous mode with a 50 % duty cycle. A preamplified Si
PIN photodetector was used to detect the backscattered light. Later these results were compared with a measurement that utilizes a conventional Anritsu
OTDR with a 850 nm wavelength. The length of the fiber obtained is 1313.99 m and shows a deviation of 0.46 % for the first measurement and 1303.89
m with a deviation of 0.38 % for the second measurement. The attenuation coefficient for that fiber is 2.65 with a deviation of 16.22 % for the
first measurement and 2.58 with a deviation of 13.16 % for the second measurement. An adjustable BK7 glass plate was used for signal
optimization in the system. Results show that maximum coupling and also maximum backscattered signal occurs when the BK7 glass window is rotated
35° anticlockwise.


G. Keiser. Optical Fiber Communications. 3rd edition. Singapore: McGraw-Hill Higher Education. 2000.

M. Tateda and T.Horiguchi. Advances in Optical Time-Domain Reflectometry. Journal of Lightwave Technology. 1989. 8 (7) : 1217-1224.

B. J. Stinson. Design and Test Of An Event Detector And Locator For The Reflectoactive Seals System. M.Sc Thesis. The University of Tennessee,

Knoxwill; 2006.

J.C. Palais. Fiber Optic Communications. 4th edition. New Jersey, U.S.A: Prentice-Hall. 1998.

S.O Kasap. Optoelectronics and Photonics. Canada: Prentice-Hall, 2001.

D. L. Phillen, Ian A. White, Jane F. Kuhl and Stephen C. Mettler. Single-Mode Fiber OTDR: Experiment and Theory. IEEE Journal Of Quantum

Electronics. 1982. 10 (18): 1499-1508.

J. Crisp. Introduction to Fiber Optics. Britain : Newnes. 1996.

J- Fiber GmbH. Wide Grade Multimode Fiber 50/125. Jena, Germany : Trade brochure. 2005.

H. J. R. Dutton. Understanding Optical Communications. U.S.A : IBM-International Technical Support. 1998.

K.I. Aoyama, K. Nakagawa, and T. Itoh. Optical Time Domain Reflectometry in a Single-Mode Fiber. IEEE Journal of Quantum Electronics.

6 (17): 862-868