Theoretical investigation of the temperature effects on the performance of fiber Sagnac interferometer-based optical intensity modulator and microwave photonic mixer

Abstract

In this paper, analytical research has been done on the temperature-dependent performance of the fiber Sagnac interferometer (SI)-based microwave photonic (MWP) structures containing polarization-maintaining fibers (PMFs) and phase modulators (PMs). PMFs are one of the critical components used in conventional SI-based fiber-optic sensors and MWP communication structures. SI-based MWP structures use the property of the polarization-maintaining feature of the PMF to maintain the state of polarization (SOP) of the emitted light to the SI and combine the counter-propagating lights coherently at the output of the SI. On the other hand, the temperature fluctuations cause a phase difference between the counter-propagating lights inside the SI, which is used in fiber-optic temperature sensors to measure and monitor the environment temperature changes. In contrast, the temperature change effects on SI-based MWP communication structures' performance have not been described yet. In this paper, the impact of the temperature changes on the SI-based MWP structures' performance containing PMFs and PMs are investigated theoretically. In particular, the mentioned effect is analyzed in detail on the performance of two SI-based devices containing PMFs and PMs, i.e., an intensity modulator and an MWP mixer. It is shown that the performance of these structures is altered by temperature changes which must be considered in the analysis and design of the MWP structures based on SI, PMs, and PMFs.