Optical Vector Network Analyzer Based on Unbalanced Amplitude-Phase Modulation

A comparative analysis of the existing and prospective symmetric type optical vector network analyzers (OVNA) characteristics is carried out. The reserves for improving the metrological and technical-economic characteristics of analyzers of this type, based on the use of methods and means of amplitude-phase modulation (APM) of an optical carrier, are revealed.Amplitude unbalanced symmetric type OVNA based on the amplitude Mach-Zehnder modulator (AMZM) and APM is proposed. An analysis of the methods, forming unbalanced AM radiation at the output of AMZM by means of APM, realized at various operating points of the modulator is made. Theoretical substantiation of the method for characterization frequency characteristics of spectral elements (SE) by amplitude and phase, based on unbalanced AM-radiation is given. The analysis of methodical errors of method realization is carried out. Computer simulation of the amplitude unbalanced OVNA and experimental probing of the fiber Bragg grating (FBG) are discussed.The estimation of the main methodological errors in measuring enabled us to determine the measurement error in 0.2 dB and 2 °, which is in times of magnitude smaller than the required value for spectrum analyzers, achievable with the help of known spectral or vector measurement methods.