Detecção heteródina do campo elétrico da luz transmitida por amostras atômicas

Abstract

This work presents the heterodyne detection technique for light electric fields, a photodetection method capable of measuring both the amplitude and phase of an electromagnetic field. Applied to the context of light-matter interaction, the study of this photodetection technique allows the complete characterization of the electric field of light coherently transmitted by a cloud of cold atoms. Thus, after presenting the Beer-Lambert Law, which governs the behavior of light intensity coherently transmitted by atomic samples, and the principles behind the heterodyne detection technique, the construction of the experimental setup is detailed, explaining the particularities of the optical and electronic circuits, as well the digital demodulation carried out in Python language in order to treat the experimental data. Finally, as the main results of this work, a system calibration stage is carried out, capable of detecting light powers in the order of picoWatts. Furthermore, with digital demodulation, phase acquisition occurs with satisfactory precision. Finally, with the aim of investigating transmission through atomic samples, the system was used to capture the amplitude of the signal transmitted by a liquid sample.