Quantum Fluctuations in the Small Fabry-Perot Interferometer

Spectra of the small Fabry-Perot interferometer (FPI) of the size of the order of the wavelength, with the main mode excited by a quantum field from a nano-LED or a laser, are investigated. The input field is detuned from the FPI mode with only a few photons. We formulate the convenient model for the FPI interacting with a quantum field, and provide novel explicit expressions for the field and the photon number fluctuation spectra inside and outside the FPI, with clearly identified contributions of the quantum and the classical noise. As a result, we found the spectra structures are quite different for the field, the photon number fluctuations inside the FPI, for the transmitted and the reflected fields and note asymmetries in spectra. The quantum noise is colored (or white) inside (or outside) the FPI, which explains differences in spectra. As another novel result, we calculate the second-order time auto-correlation functions for the FPI field; they oscillate and are negative under certain conditions. Results will help the study, design, manufacture, and use of the small elements of quantum optical integrated circuits, such as delay lines or optical transistors.

Automated summary

In this study, the spectra of small Fabry-Perot interferometers (FPIs) of similar size to the wavelength are investigated when excited by a quantum field from a nano-LED or a laser. A convenient model for the interaction between the FPI and the quantum field is formulated, and novel explicit expressions for the field and photon number fluctuation spectra inside and outside the FPI are provided. The results show significant differences in spectra for different fields and note the presence of asymmetries. Additionally, negative and oscillating second-order time auto-correlation functions are calculated for the FPI field under certain conditions.