Third-harmonic generation method and system

Abstract

The invention discloses a third-harmonic generation method. The method comprises steps: a first optical fiber diameter is calculated by an eigen equation, and according to the first optical fiber diameter and incident pump power, an estimated equivalent nonlinear transmission constant mismatch amount is obtained; according to the estimated equivalent nonlinear transmission constant mismatch amount, the first optical fiber diameter is corrected to obtain a second optical fiber diameter, and thus, an optical fiber is manufactured according to the second optical fiber diameter; whether the optical power of the third harmonics generated by using the optical fiber is the maximum value is judged; if not, according to the length of the optical fiber, the roughness and the loss coefficient, the incident pump power is adjusted until the optical power reaches the maximum value; and based on the optical fiber and the adjusted incident pump power, third-harmonic generation is carried out. The method can accurately enhance the third-harmonic generation efficiency, and errors brought by problems such as an optical fiber size and the roughness can be reduced. The invention also discloses a third-harmonic generation system, a computer readable storage device and a third-harmonic generator, which have the above beneficial effects.

Description

technical field [0001] The present invention relates to the field of optics, in particular to a third harmonic conversion method and system, a computer-readable storage medium and a third harmonic converter. Background technique [0002] Due to the limitation of the gain medium, the laser cannot realize the laser output in any band, and the nonlinear optical frequency conversion is an effective method to extend the laser band. The third harmonic phenomenon in optical fiber has attracted researchers' interest for a long time. In 1983 researchers observed third harmonic generation in an optical fiber with an elliptical core. This phenomenon was subsequently studied in various glass fibers with different doping materials such as germanium, erbium or nitrogen. With the development of micro-nano fibers, researchers have found that the conversion efficiency of the third harmonic can be significantly improved by phase matching between different modes. [0003] In the prior art, ...

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Problems solved by technology

In fact, the amount of phase misalignment caused by SPM and XPM effects depends on multiple factors such as fiber diameter, pump light power, and third harmonic power, and will also change dynamically with the interaction distance. Therefore, only based on a specific estimate There is a large principle error in the preset fiber diameter

In addition, although theoretically speaking, the fiber diameter that approximately satisfies the overall phase matching condition can be designed through iterative calculation, in practice, the micro-nano fiber that is stretched adiabatically has a certain surface roughness, which makes the fiber body The diameter deviates slightly from the designed value, thus violating the phase-matching condition

Furthermore, after the optical fiber is drawn, its diameter cannot be changed. In practical applications, if relevant parameters such as pump light power and fiber length change, it is impossible to make corresponding interventions on SPM and XPM, which lacks flexibility.

In the prior art, the third harmonic conversion is usually performed by changing the fiber diameter, but due to the manufacturing process, there will always be a certain deviation between the actual diameter and the theoretical diameter of the fiber during the fiber manufacturing process, and the surface of the fiber will be There is a certain roughness that affects the third harmonic conversion effect

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