Способ обработки спектра излучения лазера на основе экспериментально записанной формы пропускания интерферометра Фабри – Перо

Abstract

At present, to create quantum frequency standards, the phenomenon of coherent population trapping (CPT) is widely used, in which, when a certain intensity is reached and the frequency interval between the spectral components coincides with the frequency of the hyperfine transition in an atom (most often in rubidium or cesium), a narrow resonance is observed in the absorption spectrum and the transmission of a cell with alkali metal vapor increases sharply. Since the amplitude of the CPT resonance critically depends on the intensity and position of the spectral components of the pump radiation, it is necessary to control the parameters of these components, which are usually recorded in digital form. This paper describes a fundamentally new method for processing the laser emission spectrum recorded with a scanned Fabry – Perot interferometer (FPI), based on using the experimentally recorded transmission form of the scanned FPI as a reference spectral component. The paper presents examples of processing the experimentally recorded radiation spectra of a diode laser with an external resonator under microwave modulation of its injection current. The error of processing by the proposed method turned out to be approximately an order of magnitude smaller than when processing by the well-known Airy formula describing the transmission of the FPI. This is explained by the fact that the Airy formula is valid for light beams whose wave front curvature is consistent with the curvature of the IFP mirrors, which is often not true in the case of a real experiment. The method can be used to process the spectra of modulated radiation of various types of lasers, which is an important task in detecting CPT resonances and further creating quantum frequency standards based on them.