Femto second compression device

Abstract

A femtosecond pulse compression device comprises a first grating and a second grating which are arranged in parallel, and the surfaces of the two gratings, which are provided with grating fringes, arearranged on the inner side of the gratings, the first grating and the second grating with the same structure are all sub-wavelength deep etching transmission gratings whose periodic times are d, thesecond grating is arranged on the second direction of the diffraction order of the transmission negative first order of the first grating, femtosecond laser pulse which needs to be compressed is incident to the first grating in a Bragg angle theta and meet the grating equation, sin theta= lambda0 / 2d, wherein theta is an incident angle, lambda0 is a center wavelength of the femtosecond laser pulse.The invention utilizes the sub-wavelength deep etching transmission gratings to constitute the femtosecond pulse compression device which has the advantages of compact structure and high efficiency.

Description

technical field [0001] The invention relates to a femtosecond laser pulse, in particular to a femtosecond pulse compression device composed of a high-efficiency sub-wavelength deep-etching transmission grating. technical background [0002] Femtosecond laser pulses have the advantages of high peak power and short duration, so they have a wide range of applications in physics, biology, chemistry, and microfabrication and microprocessing. [0003] Usually, the laser pulse generated in the femtosecond resonator has a positive chirp due to the dispersion of materials such as the gain medium in the cavity. In order to compensate the effect of material dispersion and achieve the purpose of compressing the pulse, negative dispersion elements are generally inserted inside and outside the cavity. At present, the prism pair is the most widely used dispersion compensation element, which has the advantage of low energy loss, but because the angular dispersion of the prism is relatively...

AI Technical Summary

Problems solved by technology

Due to the relatively small dispersion of materials in the femtosecond laser resonator, the distance between high-density grating pairs will be very small, and the aperture of the beam is limited, which makes the reflective grating structure very technically difficult in practical applications.

The use of a transmissive grating structure will make the problem easier to solve

However, if a transmission holographic grating is used, first of all, the high efficiency of the -1 order diffraction order cannot be guaranteed, and secondly, a good quality transmission holographic grating is difficult to manufacture, which is the problem to be solved by the present invention

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