Single channel rate for optical fiber communication has been up to 100 Gbit or even higher, thus a higher and higher bandwidth of the measuring instrument is required. Due to the limitation of electronic bottleneck, the bandwidth limit is 70~90 GHz. At present, difficulty and cost for an electric oscilloscope to be able to measure 100 Gbit/s optical communication signals are increasing. In order to break through the limitation of electronic bottleneck, some new sampling mechanism is needed to measure the ultra high speed optical communication signal or the ultra wide band optical signal. This paper introduces the basic principle of optical field sampling and the corresponding optical sampling oscilloscope that has the advantages of high time precision and ultra wide band measurement. Also introduced are the development progresses of optical sampling oscilloscope made by the authors' research group and foriegn counterparts. In addition, with continuous improvement on channel rate, the influence of physical damage of optical fiber link on signal is becoming more significant. Therefore, how to monitor physical damage turns to be a problem in the ultra high speed optical communication network. A method of measuring the dispersion and nonlinear effect of optical fiber link based on fractional Fourier transform is presented. In the end, the development of measurement technology for high speed optical fiber communication link is prospected.

optical communication  /  optical sampling  /  dispersion  /  nonlinear  /  fractional Fourier transform