Femtosecond laser carrier envelope offset frequency lock system based on heterodyne interferometric method

Abstract

The invention relates to a femtosecond laser carrier envelope offset frequency lock system based on a heterodyne interferometric method. The system is characterized by comprising a femtosecond laser light source system, an acousto-optic modulator, a controllable optical path retardation device, a light splitting prism, a first photoelectric detector, a phase lock amplifier, a phase difference voltage conversion device and a PID controller. Heterodyne interferometry can be conducted on first-level phase-shift diffraction light modulated by the acousto-optic modulator and zero-level diffraction light which is not modulated, and after mixing of interference signals with different wavelengths, direct-current level lock pulse envelope alignment is achieved; optical frequency comb envelope offset frequency is locked by means of interference signal phase, the linear process does not exist, high non-linear optical fibers, frequency doubling crystals and the like are not needed, and the system is simple in structure and low in requirement for laser energy.

Description

technical field [0001] The invention relates to a femtosecond laser carrier envelope offset frequency locking system based on heterodyne interferometry, and relates to the technical field of laser measurement. Background technique [0002] Femtosecond laser is a kind of ultrashort pulse laser, whose time-domain pulse width is in femtosecond (10 -15 s) order of magnitude. Since the birth of the femtosecond laser, due to its short pulse width, high peak power, and reliable connection between the optical frequency domain and the radio frequency domain, it has been extensively researched and applied. The fields involved include precision distance measurement, spectroscopy Measurement, frequency reference, astronomical spectral calibration, ultrafast process observation, femtosecond laser processing, etc. The femtosecond laser frequency comb is composed of equidistantly distributed comb-like spectral lines in the frequency domain, and the frequency corresponding to each spectra...

AI Technical Summary

Problems solved by technology

f-2f requires femtosecond laser spectral width to exceed one octave, and often requires the use of highly nonlinear optical fibers to perform spectral broadening pretreatment on the laser, which increases the complexity of the system and the difficulty of optical path construction; in addition, this method uses nonlinear The frequency doubling of the crystal requires the laser pulse to have sufficient energy, so this method is also difficult to apply to low-energy femtosecond lasers, or the energy of the femtosecond laser pulse must be amplified in advance, which further increases the complexity of the system

Therefore, the traditional f-2f bias frequency locking method has certain limitations

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