Method for measuring reflectivity of dual-wavelength high reflecting mirror

Abstract

The invention discloses a method for measuring the reflectivity of a dual-wavelength high reflecting mirror. The method comprises the following steps: injecting the continuous lasers of two different wavelengths with periodically modulated light intensity into a stable initial optical resonance cavity composed of two or three dual-wavelength high reflecting mirrors at the same time; when the amplitude of the output signal of the initial optical resonance cavity is higher than a set threshold, cutting off the incident laser beam and recording the cavity ring-down signal; or recording the cavity ring-down signal at the falling edge of a modulation signal, and obtaining the ring-down time [tau]01 and [tau]02 of the initial optical resonance cavity at the two laser wavelengths by use of a synchronous measurement method, spectral detection method or alternate measurement method, and calculating the average reflectivity R01 and R02 of a cavity mirror at the two wavelengths; similarly, adding a dual-wavelength high reflecting mirror to be measured into the initial optical resonance cavity according to the using angle so as to form a stable test optical resonance cavity; obtaining the ring-down time [tau]01 and [tau]02 of the test optical resonance cavity at the two laser wavelengths by use of a synchronous measurement method, spectral detection method or alternate measurement method; and obtaining the reflectivity R1 and R2 of the dual-wavelength high reflecting mirror to be measured at the two wavelengths.

Description

technical field [0001] The invention relates to a method and device for measuring the reflectivity of a high reflector, in particular to a method for measuring the reflectivity of a dual-wavelength high reflector. Background technique [0002] In recent years, high-reflectivity thin-film optical components have been increasingly used in large-scale laser systems, laser gyroscopes, gravitational wave measurements, and trace gas detection. The optical cavity ring down technology is currently the main method to accurately measure the reflectivity of high mirrors (Li Bincheng, Gong Yuan; Review of high reflectivity measurement of optical cavity ring down, "Laser and Optoelectronics Progress", 2010, 47: 021203). The invention patent of Chinese patent application number 98114152.8 "a method of measuring high mirror and high reflectivity" uses a pulsed laser system as the light source. The disadvantages of this method are: due to the poor quality of the pulsed laser beam and the ex...

AI Technical Summary

Problems solved by technology

The invention patent of Chinese patent application number 98114152.8 "a method of measuring high mirror and high reflectivity" uses a pulsed laser system as the light source. The disadvantages of this method are: due to the poor quality of the pulsed laser beam and the existence of mode competition in the ring-down cavity, etc. Factors, the measurement accuracy is restricted, and the cost of the pulse laser used is high, which increases the system cost and is not conducive to popularization and use

The invention patent of Chinese Patent Application No. 200610011254.9 "A Measurement Method of High Mirror Reflectivity" proposes a high reflectivity measurement method using a continuous semiconductor laser as a light source, but the phase-locked detection method requires a stable optical cavity output signal , the efficiency of laser power coupling into the ring-down cavity is low. When the reflectivity of the cavity mirror reaches a certain level, the output signal amplitude of the optical cavity decreases, and the signal-to-noise ratio decreases, which makes it difficult to adjust the device and limits the maximum reflectivity that can be measured. and measurement accuracy

[0003] The above measurement methods and devices can only measure the reflectivity of a high reflector at a single wavelength, and cannot simultaneously measure the reflectivity of a dual-wavelength high reflector at two wavelengths

Images