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Description
Accurate temperature monitoring is essential in a wide range of scientific and technological applications, particularly in systems whose performance is sensitive to thermal variations. In thermal radiometry, temperature measurement can play a central role in the determination of the absorbed radiant power. In electrical substitution radiometers, for example, the heating produced by incident radiation is compared with that produced by an equivalent electrical power, making precise temperature sensing a fundamental element of the measurement process. In this context, thermo-optic sensors are attractive because they can provide compact integration, optical readout, and potentially fast response times. These characteristics make integrated thermo-optic devices promising candidates for solar radiometric instrumentation. This work presents the development and fabrication of an integrated thermo-optic sensor based on a Mach–Zehnder Interferometer (MZI). The proposed device consists of Ta₂O₅-core pedestal waveguides fabricated on a silicon substrate. Its operating principle is based on the temperature dependence of the optical properties of the waveguide material. Temperature variations modify the effective refractive index and, consequently, the optical path length of the interferometer arms. The resulting phase difference between the two arms changes the interference condition at the MZI output, providing a mechanism for converting temperature variations into measurable changes in optical intensity. The fabrication of the proposed structures demonstrates the technological feasibility of implementing MZI-based thermo-optic devices using Ta₂O₅ pedestal waveguides. The fabricated devices represent an initial step toward the development of compact integrated temperature sensors for radiometric instrumentation. Further work is required to integrate the thermo-optic device with the other components of the radiometric system and to evaluate its operation as part of a complete instrument.