A self-similar mode-locked fiber femtosecond laser based on spectral compression and amplification

Abstract

A self-similarity mode locking optical fiber femtosecond laser device based on spectrum compression and amplification is composed of an optical fiber coupling output laser diode, a wavelength division multiplexing coupler, a ytterbium-mixed monomode optical fiber, an optical fiber frequency spectrum filter, a monomode optical fiber, an optical fiber collimator, a quarter-wave plate, a half-wave plate, a polarization splitting prism, a 45-degree reflector, a grating and an optical fiber isolator. Spectrum is compressed by using the self-phase modulation generated when negative chirp pulses are amplified in the ytterbium-mixed monomode optical fiber, narrow-band chirp-free picosecond pulses are formed, the optical fiber frequency spectrum filter is used for eliminating residual side lobes in nonlinear spectrum compression, self-similarity evolution is completed in the monomode optical fiber, broadband linear chirp parabola pulses are output directly, and Fourier transformation extremity femtosecond lasers are output after chirps are eliminated. The self-similarity mode locking optical fiber femtosecond laser device is high in efficiency, large in self-similarity evolution spectrum widening amount, capable of obtaining Fourier transformation extremity femtosecond laser pulses high in energy and narrow in pulse width, compact in structure and easy to operate.

Description

technical field [0001] The invention belongs to the technical field of ultrafast lasers, in particular to a self-similar mode-locked fiber femtosecond laser based on spectrum compression and amplification. Background technique [0002] Passively mode-locked fiber femtosecond lasers have outstanding advantages such as low cost, compact structure, simple operation, self-starting, good beam quality and strong stability. There are a wide range of applications in scale distance measurement, biomedical imaging, tissue processing, and nanodiagnostics. The formation process of femtosecond laser pulses in passively mode-locked fiber lasers is mainly the evolutionary balance process of gain, group velocity dispersion and self-phase modulation. Saturable absorbers play a role in initiating and stabilizing mode-locking, and the most commonly used method is nonlinear polarization rotation. In the case of negative dispersion in the fiber laser cavity, the balance of group velocity dispe...

AI Technical Summary

Problems solved by technology

Among them, in the first self-similar-soliton mode-locking method, the pulse energy amplification and spectral broadening are ultimately limited by the pulse soliton fission in the negative dispersion fiber; while the second dissipative self-similar mode-locking method usually uses a combination of diffraction gratings The fiber collimator forms a Gaussian narrow-band filter to achieve strong spectral filtering to complete the pulse self-similar amplification evolution in the gain fiber. This cavity structure not only introduces too many spatially discrete components, but also takes up a large space and is difficult to adjust the optical path. , lose the most important advantages of compactness and easy operation of fiber lasers, and this way of narrowing and amplifying the pulse spectrum directly with an additional spectrum filter device loses most of the intracavity pulse energy, which is not conducive to high energy and narrow pulse width femtosecond laser pulse output

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