[OPTICAL REVIEW Vol. 3, No. 6B (1996) 556-559]
High-Resolution Optical Time Domain Reflectmetry Based on a Broadband Continuous Wave Multimode Laser Diode
Yishu WANG,1 Tadayuki FUNABA,2 Tsutomu ICHIMURA2 and Naohiro TAN-NO2
1R&D Center, Advantest Corporation, 1-16-1, Fujimi-cho, Gyoda, Saitama, 361 Japan, 2Department of Electronics and Information Engineering, Yamagata University, Yonezawa, 992 Japan
(Received July 22, 1996; Accepted August 20, 1996)
A broadband light source can be obtained by operating a multimode laser diode with a bias current below threshold. We propose an optical time domain reflectometer for high-resolution with a broadband cw multimode laser. The emission spectrum of the multimode laser diode that affects an interference signal is investigated. With this method, the spatial resolution is measured as 11.5 μm, corresponding to that of 38.3-fs pulses, and a minimum detectable reflectivity <-90 dB is achieved.
Key words : optical reflectometry, multimode laser, coherence function, spatial resolution