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21 November 2007 Coded optical time domain reflectometry: principle and applications
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Proceedings Volume 6781, Passive Components and Fiber-based Devices IV; 678129 (2007)
Event: Asia-Pacific Optical Communications, 2007, Wuhan, China
In this paper, we will briefly outline our contributions for the physical realization of coded OTDR, along with its principles and also highlight recent key results related with its applications. For the communication network application, we report a multi-port / multi-wavelength, high-speed supervisory system for the in-service monitoring of a bidirectional WDM-PON system transmission line up to 16 ports x 32 nodes (512 users) capacity. Monitoring of individual branch traces up to 60 km was achieved with the application of a 127-bit simplex code, corresponding to a 7.5dB SNR coding gain effectively reducing the measurement time about 30 times when compared to conventional average mode OTDR. Transmission experiments showed negligible penalty from the monitoring system to the transmission signal quality, at a 2.5Gbps / 125Mbps (down / up stream) data rate. As an application to sensor network, a Raman scattering based coded-OTDR distributed temperature sensor system will be presented. Utilizing a 255-bit Simplex coded OTDR together with optimized sensing link (composed of cascaded fibers with different Raman coefficients), significant enhancement in the interrogation distance (19.5km from coding gain, and 9.6km from link-combination optimization) was achieved to result a total sensing range of 37km (at 17m/3K spatial/temperature resolution), employing a conventional off-shelf low power (80mW) laser diode.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Namkyoo Park, Jeonghwan Lee, Jonghan Park, Jae Gwang Shim, Hosung Yoon, Jin Hee Kim, Kyoungmin Kim, Jae-Oh Byun, Gabriele Bolognini, Duckey Lee, and Fabrizio Di Pasquale "Coded optical time domain reflectometry: principle and applications", Proc. SPIE 6781, Passive Components and Fiber-based Devices IV, 678129 (21 November 2007);

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