Photo-thermal weak absorption testing device and method

Abstract

The invention provides a photothermal weak absorption testing device and method, which belong to the technical field of testing the absorptivity of optical elements. The sample is placed on the fine-tuning platform. The position of the sample to be tested is adjusted by the fine-tuning platform, so that the pump light emitted by the first light source passes through the central axis of the sample to be tested and focuses on a preset point to be measured of the sample to be tested, so that the second The probe light emitted by the light source also passes through the central axis of the sample to be measured and is focused to the preset point to be measured, and the focus spot area of ​​the probe light is larger than the focus spot area of ​​the pump light. The detection light of the sample to be measured is incident on the detector. The photothermal weak absorption test device and method provided by the embodiments of the present invention effectively realize the test of the photothermal weak absorption characteristics of an optical structure such as an optical fiber or an optical fiber preform whose refractive index is axisymmetrically distributed.

Description

technical field [0001] The invention relates to the technical field of testing the absorptivity of optical elements, in particular to a photothermal weak absorption testing device and method. Background technique [0002] Fiber lasers have many advantages such as high efficiency, good heat dissipation, high output beam quality, compact structure, and easy maintenance. They are widely used in various fields such as communications, industry, military, and medical treatment. With the expansion of application fields and the improvement of actual demand, the output power of lasers has been continuously increased. [0003] The gain medium of a fiber laser is an active fiber. The optical and material properties of the active fiber determine the output capability and performance of the fiber laser, while the fiber is obtained by pulling down a fiber preform at high temperature. The quality of the preform determines the quality of the fiber. quality. The doping uniformity of the ac...

AI Technical Summary

Problems solved by technology

However, the test object of the existing photothermal weak absorption test equipment is an optical material or film with a uniform distribution of refractive index. If it is directly used to test optical structures such as optical fibers or optical fiber preforms with axisymmetric distribution of refractive index, it will cause pumping problems. The light and the probe light are reflected or refracted multiple times inside the above-mentioned optical structure. Since the wavelengths of the probe light and the pump light are quite different, the transmission paths may be different due to refraction and reflection inside the optical fiber, and the focal spots may no longer overlap. At this time, the results detected by the receiving device cannot reflect the real material properties of the above-mentioned optical structure, and the reliability is poor

Another equally important point is that because the detection light carrying the absorption information is refracted and reflected many times, its outgoing position will generally deviate from the receiving surface of the receiving device, and the amount of deviation will usually change with the change of the test position, so that the receiving surface The detection result is affected due to the inability to receive the complete signal spot

Therefore, it is impossible to reliably test the light and heat weak absorption performance of optical structures such as optical fibers or optical fiber preforms with axisymmetric distribution of refractive index using existing heat absorption testing equipment

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