Chapter 6 - Optical system performance measurements

Abstract

This chapter discusses techniques to measure performance of digital fiber-optic systems and sub-systems. After an overview of digital optical transmission systems and their performance specifications in Section 6.2, definitions of receiver sensitivity and the required optical signal-to-noise ratio (R-OSNR) are presented in Section 6.3. Section 6.4 discusses the measurement of high-speed optical waveforms and the importance of time-based calibration. Section 6.5 introduces a time jitter definition and basic techniques to characterize time jitter. Section 6.6 presents several in situ performance-monitoring techniques using data traffic carried in the system as the probing signal. Section 6.7 reviews non-linear crosstalk in wavelength-division multiplexed systems such as cross-phase modulation, four-wave mixing, and the Raman effect. Section 6.8 discusses optical performance monitoring based on digital coherent optical transceivers. Section 6.9 discusses the impact of R-OSNR due to chromatic dispersion, self-phase modulation, and optical filter misalignment. The last section, Section 6.10, discusses fiber-optic recirculating loops, which is a very useful instrument in long-distance optical transmission system measurement.