CN104914645B - Multicolor femto-second laser pulse generation - Google Patents

Abstract

A multi-color femtosecond laser generating device, its composition includes: a first focusing element is arranged on the main optical path, two transparent solid sheets located at the focal point of the focusing lens, a second focusing element, a filter hole, two chirp Chirp mirror to obtain spectrally broadened femtosecond laser pulses, and then use the third focusing element to focus, the spectrally broadened laser pulses are split by a dichroic mirror, and the reflected light of the dichromatic mirror passes through the delay line composed of two mirrors and The other reflector is incident on the transparent nonlinear material, and the transmitted light is also incident into the nonlinear material through the two reflectors, and the multicolor can be obtained by adjusting the two beams of light to coincide in time and space in the glass sheet Femtosecond laser. The device of the invention has the characteristics of compact structure, economical and practical, convenient device construction, wide spectral range of obtained polychromatic light and adjustable center wavelength.

Description

Multi-color femtosecond laser generator

technical field

The invention relates to a femtosecond laser, in particular to a multi-color femtosecond laser generating device. It has application prospects in many related fields such as femtosecond laser spectroscopy and femtosecond laser microscopic imaging.

technical background

Femtosecond lasers have important applications in many cutting-edge scientific experiments such as physical optics, chemical optics, and bio-optics. Multiple femtosecond laser spots with adjustable center wavelength can be generated at one time by cascaded four-wave mixing, which has a good application prospect. Cascaded four-wave mixing requires two beams of incident light, which can come from a hollow fiber compression device, a non-collinear parametric amplifier, or a broadband Ti:sapphire amplifier, but the device is complex, and the experimental equipment is expensive and takes up a lot of space; this The two beams of incident light can also be generated from white sapphire sheets, or air filaments, but the spectral range of polychromatic light produced in this way is relatively narrow, and the above factors limit the application of devices based on cascaded four-wave mixing polychromatic light generation.

Contents of the invention

The object of the present invention is to provide a multi-color femtosecond laser generating device. In order to conveniently generate a multi-color femtosecond laser with an adjustable wide-spectrum center wavelength, the device only uses a plurality of transparent solid sheets to broaden the incident light, which is used for subsequent Cascaded four-wave mixing provides sufficient frequency components to extend the spectral range of the generated polychromatic light while simplifying the experimental setup.

The technical solution of the patent of the present invention is as follows:

A multi-color femtosecond laser generating device is characterized in that its composition includes: a first focusing element, a first transparent solid sheet, a second transparent solid sheet, a second focusing element, a filter aperture, a first A chirped mirror, a second chirped mirror, a neutral density attenuation sheet, a third focusing element and a dichroic mirror, the dichromatic mirror divides the spectrum-broadened laser pulse into reflected light and transmitted light, and the reflected light passes through After the first reflector, the second reflector, and the third reflector, it is incident on the nonlinear transparent solid material, and the transmitted light passes through the fourth reflector, and is also incident on the nonlinear transparent solid after being reflected by the fifth reflector. material, the first transparent solid sheet, the second transparent solid sheet is located at the focal point of the first focusing element and the second focusing element, and the first chirped mirror and the second chirped mirror respectively reflect three incident light, the first reflector and the second reflector are located on a mobile platform, which has a mechanism to move along the direction of the incident light of the first reflector, and the nonlinear crystal is located on the third The focal point of the focus element.

The thicknesses of the first transparent solid sheet and the second transparent solid sheet are on the order of hundreds of microns.

The non-linear solid transparent material is N-WG280 glass sheet, white gemstone sheet or calcium fluoride thin sheet.

The features of the present invention are:

The device of the present invention uses a plurality of transparent solid sheets to broaden the incident spectrum, can obtain high-energy and wide-spectrum laser pulses, and also provides sufficient frequency components for the subsequent cascaded four-wave mixing, and greatly simplifies the experimental device and experimental equipment. The economy is cheap.

The device can obtain a multi-color femtosecond laser with a total spectral range covering ultraviolet to near infrared.

The present invention can change the central wavelength of the obtained polychromatic light by adjusting the intersection angle of the cascaded four-wave mixing incident light.

Description of drawings

Fig. 1 is the optical path diagram of multicolor femtosecond laser generating device of the present invention

Fig. 2 is the polychromatic femtosecond laser spot figure that the present invention produces

Figure 3 is the spectrum information diagram of the multicolor femtosecond laser obtained experimentally

Figure 4 is an adjustment diagram of changing the angle to the central wavelength of the obtained polychromatic femtosecond laser

detailed description

The present invention will be further described below in conjunction with the accompanying drawings, but the protection scope of the present invention should not be limited thereby.

As shown in Figure 1, it can be seen from the figure that the multicolor femtosecond laser generating device of the present invention includes: a first focusing element 1, a first transparent solid sheet 2, a second transparent solid sheet 3, a second Focusing element 4, filter aperture 5, first chirped mirror 6, second chirped mirror 7, neutral density attenuation sheet 8, third focusing element 9, dichroic mirror 10, after the dichromatic mirror 10 broadens the spectrum The laser pulse is divided into reflected light and transmitted light, the reflected light is incident on the nonlinear transparent solid material 16 after passing through the first reflector 11, the second reflector 12, and the third reflector 15, and the described transmitted light After being reflected by the fourth reflector 13 and the fifth reflector 14, it is also incident on the nonlinear transparent solid material 16, and the first transparent solid sheet 2 and the second transparent solid sheet 3 are located in the first focusing element 1 At the focal point of the second focusing element 4, the first chirped mirror 6 and the second chirped mirror 7 respectively reflect the incident light three times, and the first mirror 11 and the second mirror 12 are located on a moving platform Above, the mobile platform has a mechanism to move along the incident light direction of the first reflector 11 , and the nonlinear transparent solid material 16 is located at the focal point of the third focusing element 9 .

The non-linear transparent solid material 16 is N-WG280 glass sheet. The concrete device of embodiment is:

The incident light with a single pulse energy of 130 microjoules is incident on the first spherical lens 1 with a focal length of 700 mm, and the first fused silica sheet 2 and the second fused silica sheet 3 with a thickness of 0.18 mm are placed near the focal point, and the two fused silica sheets are adjusted The position of the sheet until the outgoing beam presents a stable multi-ring structure, then use the second spherical lens 4 with a focal length of 400mm to collimate the outgoing beam, and filter the central part of the beam through the filter aperture 5, and then the beam is incident on the first chirped mirror 6 and the second A chirped mirror 7, the incident light is reflected three times on each chirped mirror, and the chirped mirror can provide dispersion compensation of -40fs ² each time, and then the light beams are respectively incident on the neutral density attenuator 8, and the third focal length is 1000mm Spherical lens 9, on the cut-off frequency 800nm dichroic mirror 10, and described dichromatic mirror 10 divides the laser pulse after spectral broadening into reflected light and transmitted light, and described reflected light passes through first reflecting mirror 11, second reflecting mirror 12. After the third reflector 15, it is incident on the 0.5mm thick N-WG280 glass sheet of the nonlinear crystal, and the transmitted light is incident on the nonlinear transparent solid after being reflected by the fourth reflector 13 and the fifth reflector 14 Material 16, the first reflector 11 and the second reflector 12 are located on a mobile platform, the mobile platform has a mechanism to move along the incident light direction of the first reflector 11, the nonlinear crystal 16 is located The focal point of the third spherical lens 9 . Adjust the time and space of the two beams of incident light to overlap in the nonlinear crystal 16 at a cross angle of 3°, and you can see the generation of multiple colored spots on both sides of the incident light. As shown in Figure 2, the color of the polychromatic light changes from red to Dark blue; use a fiber optic spectrometer to collect the spectral information of these polychromatic spots, as shown in Figure 3, it can be seen that the spectral range of these polychromatic lights is very wide, covering 377nm to 970nm; adjusting the intersection angle of the two incident lights can change the participating To the frequency components in the four-wave mixing, thereby changing the central wavelength of the obtained polychromatic light, as shown in Figure 4 is the change of the central wavelength of the polychromatic light when the incident light crossing angle is 3° and 4.5°. Experiments show that the experimental device is economical, simple, easy to build and convenient to adjust, and the multicolor femtosecond laser spectrum generated can cover a wide range from 377nm to 970nm, which has a good application prospect.

Claims (3)

1. A multicolor femtosecond laser generating device is characterized in that its composition comprises: the first focusing element (1), the first transparent solid sheet (2), the second transparent solid sheet (3), The second focusing element (4), the filter aperture (5), the first chirped mirror (6), the second chirped mirror (7), the neutral density attenuation sheet (8), the third focusing element (9) and Dichroic mirror (10), described dichroic mirror (10) divides the laser pulse after spectrum broadening into reflected light and transmitted light, and described reflected light passes through the first reflecting mirror (11), the second reflecting mirror (12) , after the third reflecting mirror (15), it is incident on the non-linear transparent solid material (16), and the transmitted light is also incident on the non-linear transparent solid material (16) after being reflected by the fourth reflecting mirror (13), and reflected by the fifth reflecting mirror (14). A linear transparent solid material (16), the first transparent solid sheet (2) and the second transparent solid sheet (3) are located near the focus of the first focusing element (1) and the second focusing element (4), By adjusting the positions of the two transparent solid sheets, the outgoing light beam presents a stable multi-ring structure, the first chirped mirror (6) and the second chirped mirror (7) respectively reflect the incident light three times, and the first reflected The mirror (11) and the second reflection mirror (12) are located on a mobile platform, which has a mechanism to move along the incident light direction of the first reflection mirror (11), and the non-linear transparent solid material (16) Located at the focal point of the third focusing element (9). 2. The multi-color femtosecond laser generating device according to claim 1, characterized in that the thickness of the first transparent solid sheet (2) and the second transparent solid sheet (3) is on the order of hundreds of microns. 3. The multi-color femtosecond laser generating device according to claim 1, characterized in that the nonlinear transparent solid material (16) is N-WG280 glass sheet, white sapphire sheet or calcium fluoride sheet.