EA-053297-B1 - A METHOD FOR STABILIZING NARROW-BAND SOURCES OF NON-CLASSICAL STATES OF LIGHT OBTAINED BY INTRACAVITY GENERATION OF SPONTANEOUS PARAMETRIC SCATTERING OF LIGHT, AND A DEVICE FOR ITS IMPLEMENTATION

EA053297B1EA 053297 B1EA053297 B1EA 053297B1EA-053297-B1

Abstract

The invention relates to the field of quantum and nonlinear optics, quantum electronics. A device for stabilizing narrow-band sources of non-classical states of light obtained by intracavity generation of spontaneous parametric scattering of light consists of the following, optically interconnected and sequentially arranged on the optical axis: a tunable single-frequency reference laser; a beam splitter; a system of input and output mirrors, inside which a nonlinear optical element is located, placed in a thermostatting device; a beam splitter; a cutoff filter; a wavelength meter; a piezomechanical linear translator; an optical system. The claimed method includes generating reference radiation at a target wavelength; scanning the transmission of the optical resonator of the source of non-classical states of light using a tunable single-frequency reference laser and a wavelength meter; changing the effective optical length of the source resonator; detuning the reference laser radiation from the target wavelength; Stabilization of a tunable single-frequency reference laser using a wavelength meter; stabilization of the source's optical resonator; and adjustment of the effective length of the optical resonator. The claimed method and device enable stabilization of narrow-band non-classical states of light with an accuracy of up to the sub-MHz range, obtained through the process of intracavity generation of spontaneous parametric light scattering.

Inventors

Акатьев Дмитрий Олегович
Латыпов Ильнур Зиннурович

Assignees

ОТКРЫТОЕ АКЦИОНЕРНОЕ ОБЩЕСТВО "РОССИЙСКИЕ ЖЕЛЕЗНЫЕ ДОРОГИ"

Dates

Publication Date: 20260504
Application Date: 20240226
Priority Date: 20230420

Claims (2)

tunable single-frequency reference laser after beam splitter 2. If the wavelength of reference laser 1 deviates from the target wavelength, control unit 11 commands reference laser 1 to change the wavelength Δλ κορεκρΗΗ = λ H3M - The measured intensity Iq is recorded in control unit 11 for subsequent use in the stabilization procedure of the source's optical resonator. The stabilization procedure of tunable single-frequency reference laser 1 continues until the user cancels this command in control unit 11. The procedure for stabilizing the optical resonator of the source consists of monitoring the parameter I OTH = (1 res - I CTa6 ) / Iq, where I res is the intensity that has passed through the optical resonator of the source and is measured using the wavelength meter 8. When the parameter I rel deviates from 0, the control unit 11 commands the piezomechanical translator 10 to shift A^stab - Etn * 6-75)/1/ sta b iliza tion of the II of the output mirror 4 in order to change the effective length of the resonator and thereby shift the central wavelength of the mode of the optical resonator of the source to the original αν. - the derivative calculated in advance by the control unit 11 from the transmission data of the optical resonator of the source, Y stabilization = cA stabilization L - the length of the optical resonator, which is programmed into the control unit 11. The procedure is carried out until 1 rel becomes 0. In this way, the stability of the reference laser radiation and the effective optical length of the resonator of the source of non-classical states of light are simultaneously monitored using a wavelength meter. Thus, the claimed invention is a method for stabilizing narrow-band sources of non-classical light states obtained by intracavity generation of spontaneous parametric light scattering, and a device for implementing this method, expanding the arsenal of tools for this purpose. The effectiveness of the claimed method lies in the ability to perform highly accurate wavelength stabilization of a narrow-band source of non-classical light states using a wavelength meter, which also enables direct monitoring of the wavelength of the generated non-classical light states. Implementation of the claimed method is demonstrated using a laboratory prototype of the claimed device. The claimed method and device enable stabilization of the wavelength of a source of non-classical light states with an accuracy of less than 1 MHz by using a wavelength meter and monitoring the effective length of the source's optical resonator based on changes in the relative transmittance of a reference laser source through the optical resonator mode. This technique enables simultaneous stabilization of a reference tunable laser source and a source of narrow-band non-classical light states by directly measuring the wavelength of a tunable single-frequency laser. CLAUSES OF THE INVENTION 1. A method for stabilizing narrow-band sources of non-classical states of light obtained by intracavity generation of spontaneous parametric scattering of light, including generating reference radiation at a target wavelength, scanning the transmission of the optical resonator of the source of non-classical states of light using a tunable single-frequency reference laser and a wavelength meter, changing the effective optical length of the source resonator so that maximum transmission is observed at the target wavelength, detuning the reference laser radiation from the target wavelength so that the transmission of the optical resonator is T = 0.75, and the laser spectrum does not intersect with the spectrum of non-classical states of light, stabilizing the tunable single-frequency reference laser using the wavelength meter, stabilizing the optical resonator of the source using a stabilized tunable single-frequency reference laser and a wavelength meter, adjusting the effective length of the optical resonator using a piezomechanical translator in the event of a change in transmission stabilized reference single-frequency laser through the optical resonator of the source.
2. A device for stabilizing narrow-band sources of non-classical states of light obtained by intracavity generation of spontaneous parametric scattering of light, comprising optically interconnected and sequentially located on an optical axis: a tunable single-frequency reference laser connected to a control unit and to a wavelength meter also connected to the control unit, a beam splitter, at least one, optically connected to the wavelength meter, an optical resonator, which is a system of input and output mirrors, the centers of curvature of which are located on the same axis with the radiation of the single-frequency reference laser and inside which a nonlinear optical element is located, placed in a thermostatting device, wherein the output mirror is connected to a piezomechanical linear translator connected to the control unit, a beam splitter, at least one, optically

Description

The invention relates to the field of quantum and nonlinear optics, quantum electronics, namely to a method for stabilizing the wavelengths of various non-classical states of light, for example single-photon or two-photon entangled states, based on spontaneous parametric scattering, as well as to a device for implementing the said method, and can be used in various fields, including spectroscopy, fiber optic communications, medicine, etc., in devices for controlling the spectrum of laser radiation. Controlling radiation parameters is one of the fundamental tasks of quantum and nonlinear optics. These parameters include polarization, angular and spectral distributions, correlation and temporal properties, and others. A pressing issue is controlling the emission spectrum of sources that generate optical quantum information carriers. In particular, one important task is controlling and stabilizing the wavelength of sources of narrow-band nonclassical light states. Intracavity generation of spontaneous parametric scattering (SPS) is the primary method for producing narrow-band nonclassical light states. The primary method for stabilizing such devices is by controlling the effective length of the resonator, which involves controlling the phase-matching conditions of the nonlinear medium in which the SPS generation process occurs, or by controlling the position of the output mirror of the optical resonator. The invention [RU2708538 C1, 03.06.2019] considers a method for stabilizing the length of single-photon states generated in the process of spontaneous parametric light scattering (SPLS) using an external uniform electric field applied to a nonlinear medium in which the SPLS generation occurs. The said method is implemented by a device consisting of an optically coupled and sequentially arranged nonlinear optical element placed simultaneously in a thermostatic device and in a source of an external electric field; a system of cutoff interference filters for cutting off pump radiation; a device for dividing a photon flux; a dispersive element; a photon counter. The dispersive element or the photon counter have the ability to change their position to adjust the arrangement relative to each other so that the aperture of the photon counter captures radiation from the dispersive element at a given wavelength; the device also includes a control unit to which a thermostatic device, a source of an external electric field and a photon counter are connected. This method does not consider the case of intracavity generation of parametric light scattering. In the case of using an external uniform electric field with intracavity generation of the SPR, two phenomena occur: 1) a change in the effective length of the resonator, due to a change in the refractive index of the nonlinear medium (electro-optic effect), which makes it possible to control the intermode distance of the optical resonator and, consequently, stabilize it; 2) a change in the phase-matching conditions, which can lead to a significant shift in the SPR spectrum (with the possible use of large fields) and a decrease in the generation efficiency on the required resonator mode. The invention [US2008/0063015 A1, 13.03.2008] discloses a stabilization method using a stabilized single-frequency laser and a temperature controller for a nonlinear crystal, which essentially controls the effective length of a Fabry-Perot optical resonator. Changing the temperature of the nonlinear medium alters the refractive index and the effective length of the Fabry-Perot optical resonator. The main disadvantage of this method is the high inertia of the change, since establishing a new temperature balance between the environment and the nonlinear crystal requires a time that can exceed 1 s or more. Furthermore, the temperature of the nonlinear medium is subject to significant environmental influences: changes in external conditions, the emergence of localized vortex air flows, etc., which leads to temperature fluctuations and, consequently, broadening of the spectral line that needs to be stabilized. A number of studies use the Pound-Drever-Hall (PDH) method [Dreyer, Hall, Kowalski, Hough, Ford, Munley, Ward, Laser phase and frequency stabilization using an optical resonator, Appl. Phys. B: Laser Opt., 1983, Volume 31, Number 2, pp. 97-105] to stabilize the effective length of a resonator [US 10331012 B2, 25.01.2019]. The method is based on mixing several beams of reference laser radiation: a phase-modulated reference laser beam reflected from the input mirror of the optical resonator and a laser beam scattered through the input mirror of the optical resonator. After mixing these two laser beams, an error signal is formed on the photodetector, which depends on the frequency detuning of the sideband/subcarrier frequencies arising from the phase modulation of the original laser radiation. Measuring the error signal generates feedback from one of the optical resonator mirrors, which is l