Method for testing pump absorption coefficient of double-clad gain fiber

Abstract

The present invention discloses a method used for testing a double-cladding gain fiber pump absorption coefficient. The method comprises the steps of (1) selecting a to-be-tested double-cladding gain fiber of which the initial length L0 is not more than 2m, welding the to-be-tested double-cladding gain fiber with a transmitting energy fiber, and coupling a pump light source into an inner cladding of the transmitting energy fiber; (2) cutting the to-be-tested double-cladding gain fiber, and testing the output powers of the pump light of different wavelengths in the pump light source under a test length L1; (3) repeating the step (2) to obtain the output powers of the pump light of different wavelengths when the length of the to-be-tested double-cladding gain fiber is L2, L3......LN separately; (4) finding out the residual pump light power of the light of which the wavelength is to be tested, and testing the pump absorption coefficient of the to-be-tested double-cladding gain fiber to the light of which the wavelength is to be tested. The method of the present invention can eliminate an unstable test result brought by the mode disturbance when the double-cladding gain fiber pump absorption coefficient is tested, and enables the accuracy and precision of the test result to be improved greatly.

Description

technical field [0001] The invention belongs to the field of fiber lasers, and relates to a method for testing the absorption characteristics of a gain fiber to pump light, in particular to a method for testing the pump absorption coefficient of a double-clad gain fiber. Background technique [0002] Compared with ordinary lasers, fiber lasers have obvious advantages in beam quality, volume, weight, efficiency, heat dissipation, etc., and have become one of the most popular research directions in the field of lasers. Single-clad gain fibers were often used in early fiber lasers, and both the pump light and the signal light were transmitted in the fiber core. Due to the small diameter and numerical aperture of the fiber core, the total power of the pump light injected into the gain fiber was limited. Restrictions restrict the power increase of fiber lasers. The structure of the double-clad gain fiber includes a core, an inner cladding and an outer cladding, and its character...

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Problems solved by technology

For example, the absorption coefficient of ytterbium-doped fiber at 976nm is very large. When building a high-power fiber laser, the nonlinear effect can be better suppressed by using 976nm pumping. However, these methods cannot give the absorption coefficient of the gain fiber at 976nm.

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