High Precise Time Delay Measurement in Optical Fiber
Due to its properties of low attenuation, high capacity and reliability, the widespread optical fiber network has become an attractive option for long-distance transmission. The signal transmission delay in fiber, as an essential characteristic, becomes a
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Abstract Due to its properties of low attenuation, high capacity and reliability, the widespread optical fiber network has become an attractive option for long-distance transmission. The signal transmission delay in fiber, as an essential characteristic, becomes a significant parameter that has broad effects on the performance of optical communications, fiber timing distribution systems, phased array antennas, and some other large-scale scientific or engineering facilities. We report a novel method for signal transmission delay measurement in optical fibers. Based on phase discrimination, dual-frequency locking and measurement, it achieves a very high measurement precision of 0.2 ps with a 0.1 ps resolution, and dynamic range over 50 km. Using a phase shift and frequency locking technique, the measurement ambiguity can be resolved within only a few seconds. It greatly simplifies the measurement procedure and requires much simpler equipment. A good agreement in measurement results with the conventional pulsed method is obtained as well. Keywords Optical fiber
Transmission Time delay
1 Introduction Optical fiber is one of signal transmission medium. With low loss, high capacity, high reliability, and many other advantages, it is increasingly widely used in various fields. The fiber transmission delay (FTD) is an important parameter of the transmission characteristics for signal transmission in optical fiber. For digital fiber-optic communications [1–3], the FTD measurement is used to estimate the transmission J. Dong B. Wang (&) H. Si L. Wang Department of Precision Instrument, State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing 100084, China e-mail: [email protected] L. Wang Department of Physics, Tsinghua University, Beijing 100084, China © Springer Nature Singapore Pte Ltd. 2017 J. Sun et al. (eds.), China Satellite Navigation Conference (CSNC) 2017 Proceedings: Volume III, Lecture Notes in Electrical Engineering 439, DOI 10.1007/978-981-10-4594-3_46
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distance, the signal distortion caused by chromatic dispersion, etc. In wavelength-division multiplexing system, the FTD is closely related to the communication bandwidth, error rate, and many other important characteristic parameters. For fiber-based time and frequency distribution and synchronization [4–7], the accuracy of FTD measurement directly determines the time synchronization accuracy. In optically controlled phased array antenna [8–10], the FTD measurement is used to control the time delay of the transmitted signal in order for specified transmit direction angle. In distributed array system [11–13], FTD measurement plays a key role in beamforming. Up to now, many techniques for FTD measurement in time domain [14–17] or frequency domain [18–20] have been developed and successfully employed. The traditional time-domain measurement methods called pulse methods, include laser pulse method and microwave pulse method. In these methods, the time interval of the before and after transm
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