Iodine molecular optical clock based on pulse-modulated broad-spectrum comb laser and its control method

Abstract

The invention relates to an iodine molecular optical clock based on a pulse-modulated broad-spectrum comb-shaped laser and a control method. The power control system of the iodine molecular optical clock generates a pulse modulation signal and transmits it to the laser system to generate a pulse signal, which is isolated from the optical feedback of the rear optical path by the isolator, and the isolator is connected to the first half-wave plate and the first polarization beam splitter in turn; The frequency-stabilizing optical path is the second half-wave plate and the second polarization beam-splitting prism connected in sequence; after the second polarization beam-splitting prism, it is divided into two beams: the beam with stronger light intensity is used as the pump laser in turn through the Glan-Taylor prism, the third half-wave beam The light beam and the electro-optical phase modulator are reflected by the third polarization beam splitter to the optical path multiplication system; the beam with weaker light intensity is used as the detection laser optical path multiplication system and the third polarization beam splitter, and is input to the laser phase detector after being received by the high-speed photodetector And high-speed servo feedback control circuit to generate the servo signal of the power control system.

Description

technical field [0001] The invention relates to the technical field of optical frequency atomic clocks and optical frequency quantum frequency standards, in particular to an iodine molecular optical clock based on a pulse-modulated wide-spectrum comb-shaped laser and a control method thereof. Background technique [0002] Iodine molecule is a simple diatomic molecule, which has about 5000 absorption lines in the visible light band of 500-650nm, especially around 532nm, iodine molecule has hundreds of strong absorption lines. Since the iodine absorption transition at 532nm is ground-state absorption, the absorption coefficient is larger and the spectral line width is narrower than other adjacent bands, so the 532nm iodine molecular frequency standard has excellent frequency stability in the visible light band, and the 1s sampling time The Allen deviation of the frequency stability can reach 5×10-14, which becomes one of the recommended standards for reproducing the meter defi...

AI Technical Summary

Problems solved by technology

The second technical problem solved by the present invention is to improve the effective utilization rate of iodine molecules in the prior art, and the length of the iodine molecule absorption pool is designed to be tens of centimeters or even several meters, which leads to high difficulty in controlling the temperature and large system volume during application. The big problem is to provide a laser frequency stability that is close to the order of magnitude. On the basis of improving the signal-to-noise ratio of the hyperfine spectral line of the iodine molecular optical clock, the length of the iodine molecular absorption cell is greatly shortened, and the miniaturization of the iodine molecular optical clock is realized. Iodine molecular optical clock and its control method based on pulse modulation broadband comb laser of molecular optical clock

The fourth technical problem solved by the present invention is aimed at the electro-optic phase modulation process of the laser by using the electro-optic phase modulator in the prior art, accompanied by a small amount of amplitude modulation. The laser frequency causes a frequency shift. If the residual amplitude modulation changes with time, the frequency shift will cause the laser frequency to fluctuate with time, resulting in the deterioration of the long-term frequency stability after the laser frequency is locked. For the influence of residual amplitude modulation, the active temperature feedback method is used to control the change of residual amplitude modulation in the electro-optical phase modulator. The first four-hole aperture and the second four-hole aperture are respectively placed at the front and rear ends of the iodine molecular absorption cell, which can Effectively solve the problem of stray light caused by the multiple transmissions on the windows at both ends of the iodine molecular absorption cell and the multiple reflections of the reflective prisms and an iodine molecular optical clock based on pulse-modulated broad-spectrum comb-shaped laser and its control method

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