High-resolution spectral response measurement based on single sideband modulation

The spectral response of passive optical devices reveals the important characteristics of their materials and functions and is an essential evaluation index in the development, production and application of optical devices. In this paper, a broadband and high-resolution spectral response measurement method is proposed based on single sideband modulation technology. The optical carrier emitted by the tunable light source is incident on the dual parallel Mach Zehnder modulator (DPMZM), and the Microwave signal emitted by the frequency source is loaded on the modulator. Combined with the bias voltage and the hybrid couple, carrier suppression single sideband (CS-SSB) modulation is realized. The modulated signal is received by the photodetector after passing through the passive optical device under test, and frequency of the single sideband modulated optical signal can be swept through the frequency source. This signal passes through the optical beam splitter, and the spectral response of the passive optical device is measured by the balance detection of two signals. A broadband high-resolution spectral response measurement system is constructed in the experiment. The experimental results show that the spectral measurement resolution of the system reaches at least 5 MHz, and the measurement range is 1528-1568 nm. This measurement method combines a tunable light source with a single sideband microwave photon scanning frequency. The system structure is simple, the measurement accuracy is high, and the measurement range is large. It can realize the spectrum response measurement of passive optical devices such as narrow linewidth filters and wavelength division multiplexers.