Cavity length-adjustable femtosecond laser

Abstract

The invention discloses a cavity length-adjustable femtosecond laser. The cavity length-adjustable femtosecond laser comprises an annular cavity, a linear branch and a cavity length adjustment automatic control module; the annular cavity comprises a polarization-maintaining isolation light splitting type wavelength division multiplexer, a transmission-type saturable absorber, a polarization beam combiner and a polarization-maintaining doped optical fiber, wherein the polarization-maintaining isolation light splitting type wavelength division multiplexer, the transmission-type saturable absorber, the polarization beam combiner and the polarization-maintaining doped optical fiber are connected with one another sequentially to form an annular structure; the linear branch includes a polarization beam combiner, a non-polarization-maintaining dispersion compensating optical fiber, an optical fiber collimator, a 45-degree Faraday rotation mirror and a pyramid prism, wherein the polarization beam combiner, the non-polarization-maintaining dispersion compensating optical fiber, the optical fiber collimator, the 45-degree Faraday rotation mirror and the pyramid prism are connected with one another sequentially; and the cavity length adjustment automatic control module includes a polarization-maintaining beam splitter, a photoelectric detector, an automatic driving control circuit and a piezoelectric ceramic which are connected with one another sequentially. The cavity length-adjustable femtosecond laser has the advantages of large cavity length tuning range, high environmental stability, simple and compact structure and the like, and can be widely applied to the laser precision measurement fields such as optical frequency comb, asynchronous optical sampling and cavity length adjustment optical sampling.

Description

technical field [0001] The patent of the invention belongs to the technical field of measurement, in particular to a fiber femtosecond laser with adjustable cavity length. Background technique [0002] As a light source, femtosecond lasers are widely used in optical frequency combs, asynchronous optical sampling ASOPS, Asynchronous Optical Sampling, cavity length adjustment optical sampling OSCAT, Optical Sampling by Cavity Tuning and other laser precision measurement fields. Its reliability also directly determines the performance of the entire measurement system. performance. [0003] Compared with solid-state femtosecond lasers, fiber femtosecond lasers have the advantages of compact structure, good stability and low cost, but their performance needs to be further improved when used in industrial fields such as precision measurement. In addition to the need to improve the mode-locking stability of fiber femtosecond lasers, it is also necessary to increase the tuning rang...

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Problems solved by technology

[0004] Since the repetition frequency of the laser is related to the length of its resonant cavity, at present, the main means to adjust the repetition frequency of the fiber femtosecond laser include: 1) Adding a fiber delay line in the laser resonator, this method has a small tunable range; 2 ) Paste the gain fiber to the piezoelectric ceramic PZT, and stretch the fiber through the PZT to adjust the cavity length. The disadvantage is that the gain fiber is easily damaged; 3) Add a movable mirror in the laser resonator, although the tuning range of the repetition frequency Larger, but less stable

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