Two-frequency DSB-SC Modulation for Relative Frequency Response Measurement of Mach-Zehnder Amplitude Modulators

Electro-optical and optoelectronic devices are widely used in the field of on board telecommunications, microwave photonics, and fiber optic sensing. Measurement of the spectral characteristics of these devices with high resolution is necessary both at the stage of their production and operation. However, using currently existing methods, it is hardly possible to effectively characterize these devices, which practically have an arbitrary response, due to the low resolution or high cost of existing measuring instruments. This article will use the basic principles of the concept of an ultra-narrow-band discrete frequencies package to build a microwave photonic spectral characteristics analyzer (MPSCA) of an amplitude electro-optical Mach-Zehnder modulator based on the double conversion of a laser carrier into a symmetric two-frequency radiation using the Il’in-Morozov method, and characterized by a high resolution at low cost. At the same time, unlike the existing MPSCA, the proposed implementation is distinguished by a universal element base, a reasonable choice of a difference frequency between two components of 50 MHz, which determines the measurement resolution, and also by obtaining an information signal tied to zero at the output.