CN115855280A - Femtosecond vortex beam self-focusing critical power measuring method and system - Google Patents
Femtosecond vortex beam self-focusing critical power measuring method and system Download PDFInfo
- Publication number
- CN115855280A CN115855280A CN202211582130.1A CN202211582130A CN115855280A CN 115855280 A CN115855280 A CN 115855280A CN 202211582130 A CN202211582130 A CN 202211582130A CN 115855280 A CN115855280 A CN 115855280A
- Authority
- CN
- China
- Prior art keywords
- femtosecond
- vortex
- focusing
- wave plate
- critical power
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Landscapes
- Lasers (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
Abstract
The invention discloses a femtosecond vortex beam self-focusing critical power measuring method and a femtosecond vortex beam self-focusing critical power measuring system, and belongs to the technical field of self-focusing critical power measurement. The device comprises a femtosecond laser output energy adjusting device, a vortex beam generating device and a fluorescence collecting device, wherein the femtosecond laser output energy adjusting device is used for adjusting the energy of incident femtosecond laser pulses, the vortex beam generating device is used for converting the femtosecond laser pulses after the energy is adjusted into femtosecond vortex beams and generating plasma filaments, and the fluorescence collecting device is used for collecting and monitoring lateral fluorescence signals of the femtosecond vortex beams. The method can simply and sensitively carry out quantitative determination on the self-focusing critical power of the femtosecond vortex beam, improve the accuracy and stability of a determination result, and is beneficial to further application of the self-focusing critical power of the femtosecond vortex beam; the problem that quantitative determination can not be carried out on the self-focusing critical power of the vortex light beam in the prior art is solved.
Description
Technical Field
The application relates to the technical field of vortex beams, in particular to a femtosecond vortex beam self-focusing critical power measuring method and system.
Background
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The group of professor mourou (awarded by the nobel physics in 2018) discovered in 1995 that high-power femtosecond lasers could form plasma filaments up to 20 meters in length and about 100 micrometers in diameter in air, thus opening the field of femtosecond laser filamentation.
The femtosecond laser filamentation refers to the formation of a plasma filament with a transmission distance far exceeding the Rayleigh distance and a diameter and laser intensity basically maintained unchanged under the combined action of the effects of Kerr self-focusing, plasma defocusing and the like when a high-power ultrafast laser pulse is transmitted in an optical medium. The femtosecond laser filamentation shows very unique physical properties, for example, when the high-power femtosecond laser is transmitted in the air, the intensity of the filament laser is maintained at 10 13 -14W/cm 2 Electron density of 10 16-18 cm -3 The filament forming length can reach hundreds of meters or even kilometers, and the formed ultra-continuous radiation spectrum can cover the range from ultraviolet to middle infrared, so that the femtosecond laser filament attracts the attention of many researchers in the world once being discovered, and the femtosecond laser filament rapidly becomes the leading-edge field of ultrafast optics.
Vortex rotation as a special optical field brings many novel physical phenomena, creates new opportunities for numerous application fields, also promotes some brand-new scientific applications, has been widely applied in the fields of optical tweezers or microparticle optical control, optical communication, laser spiral filamentation, laser micromachining, laser spectroscopy, astronomical observation, terahertz and extreme ultraviolet radiation and the like, and greatly promotes the development of the fields. In recent years, the optical vortex field is rapidly developed, and breakthrough results are continuously emerged. Vortex femtosecond laser filamentation combines the extraordinary properties of optical vortices with the ultra-intense ultrafast nature of femtosecond pulses, and can predictably produce many unusual physical phenomena and unprecedented applications. With the diversification and gradual maturity of high-power vortex femtosecond laser generation means, a plurality of research institutions and companies at home and abroad are successively added into the field, a series of researches are carried out on the filamentation transmission characteristic, the super-continuous radiation, the third harmonic wave, the micro-processing and the like of the vortex femtosecond laser, and attractive application prospects are shown in the fields of waveguide laser micro-processing, laser spectrum technology, ultra-short pulse generation, even fast ignition laser nuclear fusion and the like.
The self-focusing critical power of the vortex femtosecond laser in an optical medium is regarded as a key parameter for judging whether the laser can form filaments or not, and also as a key physical quantity for predicting whether the multifilaments can be generated or not, estimating the number of the multifilaments and the like, and the determination of the value has important guiding significance for basic research and application.
However, the studies of vortex femtosecond filamentation began for two decades and researchers are still following the self-focusing critical power expression for the continuous vortex light regime available from v.kruglov et al [ j.mod.opt.39,2277 (1992) ]. Although researchers continue to explore further based on this expression [ phys. Rev.a 77,045803 (2008); phys. Rev.A 100,013836 (2019) ], but still present a large deviation from the experimental results. This is mainly because the expression is derived on the premise of a continuous beam, and does not consider the beam splitting caused by modulation instability, and even does not consider the influence of the laser pulse width. This shows that the current theoretical expression needs to be corrected or reconstructed to be applied to the case of the vortex femtosecond laser, and the correction or reconstruction needs to be supported by experimental data, but no research for quantitatively determining the self-focusing critical power of the vortex femtosecond laser exists internationally. Currently, the only study related to the critical power of auto-focusing is the experimental study of vortex femtosecond laser filamentation in air by p.polynkin et al, university of arizona [ phys.rev.lett.111 (2), 023901 (2013) ]. However, as the researchers have demonstrated in their reports, the measurement methods they used are not suitable for quantitative measurement of the autofocus critical power, one of the main reasons is that there is no reference standard for the threshold selection of the experimental signal and subjective setting is required, the second is that they have not found a suitable method for quantitative measurement of the autofocus critical power as described in their reports. Then, they obtain the relation between the self-focusing critical power and the topological charge number through fitting the experimental data, and provide the only experimental data support about the self-focusing critical power in the aspect of vortex beam filamentation research and application.
It can be seen from the above analysis that the femtosecond vortex laser is not suitable for directly using the self-focusing critical power expression under the condition of continuous vortex beam, and the existing method cannot quantitatively determine the self-focusing critical power of the vortex beam, so that the accuracy of the determination of the self-focusing critical power is influenced, and further the research and various applications of the femtosecond vortex laser are influenced.
Disclosure of Invention
In order to solve the defects of the prior art, the application provides a method and a system for measuring the self-focusing critical power of a femtosecond vortex light beam, the self-focusing critical power of the femtosecond vortex light beam in the air is measured by a method of measuring ionized fluorescent radiation in the air by using a photomultiplier tube (PMT), the self-focusing critical power of the femtosecond vortex light beam in the air can be obtained, and the self-focusing critical power of other structural light beams, such as Airy light beams, annular Airy light beams, bessel light beams and the like, can also be measured.
In a first aspect, the present application provides a femtosecond vortex beam self-focusing critical power measurement system;
a femtosecond vortex beam self-focusing critical power measurement system, comprising:
a femtosecond laser output energy adjustment device for adjusting energy of incident femtosecond laser pulses;
the vortex beam generating device is used for converting the femtosecond laser pulse after the energy is adjusted into a femtosecond vortex beam and generating a plasma filament;
a fluorescence collection device for collecting and monitoring lateral fluorescence signals of the femtosecond vortex beam.
Furthermore, the femtosecond laser output energy adjusting device comprises a half-wave plate and a polaroid which are sequentially arranged on the same optical axis, wherein the femtosecond laser pulse sequentially passes through the half-wave plate and the polaroid, and an included angle between the half-wave plate and the polaroid is changed through rotating the angle of the half-wave plate, so that the energy of the input femtosecond laser pulse is continuously adjusted.
Further, the vortex light beam generating device comprises a first quarter wave plate, a vortex wave plate and a focusing lens which are sequentially arranged on the same optical axis;
the first quarter wave plate is used for converting the polarization state of the femtosecond laser pulse from linear polarization to circular polarization;
the vortex wave plate is used for converting the circularly polarized femtosecond laser pulse into a circularly polarized femtosecond vortex light beam;
the focusing lens is used for focusing ionized air in the air when the femtosecond vortex light beam passes through the focusing lens to generate plasma filaments.
Further, the vortex light beam generating device further comprises a second quarter wave plate arranged between the vortex wave plate and the focusing lens;
the second quarter-wave plate is used for modulating the circularly polarized femtosecond vortex light beam into a linearly polarized femtosecond vortex light beam.
Further, the fluorescence collecting device comprises a collecting lens, an optical filter, a photomultiplier and an oscilloscope;
the collecting lens is used for collecting lateral fluorescent signals of the femtosecond vortex light beams, the lateral fluorescent signals enter the photomultiplier through the optical filter, and the oscilloscope is used for monitoring and recording the intensity of the lateral fluorescent signals.
Furthermore, the optical filter comprises a band-pass optical filter and an ultraviolet-transmitting low-pass optical filter which are sequentially arranged on the same optical axis;
the band-pass filter is used for filtering a fluorescence spectrum in a gas medium, and the ultraviolet-transmitting low-pass filter is used for filtering stray light in the environment.
In a second aspect, the application provides a femtosecond vortex beam self-focusing critical power measuring method;
a femtosecond vortex beam self-focusing critical power measuring method can adopt the femtosecond vortex beam self-focusing critical power measuring system, and comprises the following steps:
step 1, starting a femtosecond laser to generate femtosecond laser pulses, wherein the femtosecond laser pulses enter a femtosecond laser output energy adjusting device to obtain femtosecond laser pulses with adjusted energy;
and 4, recording femtosecond laser pulses with different energies and signal intensity of corresponding lateral fluorescent signals, and calculating the self-focusing critical power of the femtosecond vortex beam according to the variation trend of the signal intensity.
Further, the energy of the femtosecond laser pulse is adjusted by adjusting the angle of the half-wave plate.
Further, the femtosecond laser pulse after energy adjustment sequentially passes through the first quarter wave plate, the vortex wave plate and the second quarter wave plate to generate a femtosecond vortex beam; the femtosecond vortex beam passes through a focusing lens to focus ionized air in the air, and plasma filaments are generated.
Further, the collecting lens collects lateral fluorescent signals of the femtosecond vortex light beams, the lateral fluorescent signals sequentially pass through the band-pass filter and the ultraviolet-transmitting low-pass filter to enter the photomultiplier, and the photomultiplier converts the lateral fluorescent signals into electric signals and transmits the electric signals to the oscilloscope for monitoring and recording.
Further, the femtosecond laser pulse was generated by a femtosecond laser amplifier having a center wavelength of 800nm, a pulse duration of 65fs, a repetition frequency of 1kHz, and a maximum pulse capability of 6mJ.
Compared with the prior art, the beneficial effects of this application are:
1. according to the technical scheme provided by the application, the self-focusing critical power of the femtosecond vortex light beam in the air is measured by a method of measuring ionized fluorescent radiation in the air through a photomultiplier, so that the quantitative analysis of the self-focusing critical power is realized, the method is simple, expensive imaging equipment such as CCD (charge coupled device) or ICCD (integrated circuit CD) is not needed, and the measurement cost is reduced;
2. according to the technical scheme, the photomultiplier can collect lateral fluorescence signals and amplify the lateral fluorescence signals, and sensitive measurement can be carried out on weak signals.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.
FIG. 1 is a schematic structural diagram of a femtosecond vortex beam self-focusing critical power measurement system provided in an embodiment of the present application;
FIG. 2 is a schematic flow chart of a femtosecond vortex beam self-focusing critical power measurement method provided in an embodiment of the present application;
fig. 3 is a diagram illustrating exemplary results of determining the femtosecond vortex beam autofocus critical power according to an embodiment of the present disclosure, wherein (a) is a diagram illustrating exemplary results of the femtosecond vortex beam autofocus critical power with a topological charge of 1, (b) is a diagram illustrating exemplary results of the femtosecond vortex beam autofocus critical power with a topological charge of 2, and (c) is a diagram illustrating exemplary results of the femtosecond vortex beam autofocus critical power with a topological charge of 3;
wherein, 1, half-wave plate; 2. a polarizing plate; 3. a first quarter wave plate; 4. a vortex wave plate; 5. a second quarter wave plate; 6. a focusing lens; 7. a collecting lens 8 and an optical filter; 9. a photomultiplier tube; 10. an oscilloscope.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
The embodiments and features of the embodiments of the present invention may be combined with each other without conflict.
Interpretation of terms:
critical power for self-focusing: when a high-power femtosecond laser pulse is transmitted in an optical medium, the high-power femtosecond laser pulse can experience Kerr self-focusing effect, diffraction, dispersion effect and the like, and only when the power of incident laser exceeds a certain value, the high-power femtosecond laser pulse can overcome the diffraction and dispersion effects to generate a self-focusing phenomenon, wherein the specific value is called the self-focusing critical power of the laser in the medium.
Plasma filament: when the femtosecond laser power exceeds the self-focusing critical power, the light pulse can generate a self-focusing effect, so that the light intensity is gradually enhanced to cause ionization of a medium, plasma is generated, and then a plasma filament with the transmission length far longer than the Rayleigh distance is formed under the combined action of self-focusing and plasma defocusing.
Photomultiplier tube (PMT): a vacuum electronic device for converting weak optical signals into electrical signals.
Femtosecond vortex beam: the method has the advantages of having ultrafast, super-strong and unique wavefront structure, having high energy density, simultaneously carrying orbital angular momentum, representing a plurality of unique phenomena in the transmission and the interaction with substances, and providing a new control degree of freedom for the interaction between laser and the substances.
Example one
In the prior art, the power measurement depends on expensive equipment, and the femtosecond vortex beam self-focusing critical power cannot be quantitatively analyzed, so that the measurement of the self-focusing critical power is unstable and poor in accuracy, and the application of the self-focusing critical power is influenced. Therefore, the embodiment provides a femtosecond vortex beam self-focusing critical power measuring system.
Next, a femtosecond vortex beam self-focusing critical power measuring system disclosed in this embodiment will be described in detail with reference to fig. 1.
The femtosecond vortex beam self-focusing critical power measuring system comprises a femtosecond laser output energy adjusting device, a vortex beam generating device and a fluorescence collecting device, wherein the femtosecond laser output energy adjusting device is used for adjusting energy of incident femtosecond laser pulses, the vortex beam generating device is used for converting the femtosecond laser pulses after the energy is adjusted into the femtosecond vortex beam and generating plasma filaments, and the fluorescence collecting device is used for collecting and monitoring lateral fluorescence signals of the femtosecond vortex beam.
As shown in fig. 1, the femtosecond laser output energy adjusting device comprises a half-wave plate 1 and a polarizing plate 2, the vortex beam generating device comprises a first quarter-wave plate 3, a vortex wave plate 4, a second quarter-wave plate 5 and a focusing lens 6, and the half-wave plate 1, the polarizing plate 2, the first quarter-wave plate 3, the vortex wave plate 4, the second quarter-wave plate 5 and the focusing lens 6 are sequentially arranged along the same optical axis in the aforementioned order. The femtosecond laser pulse sequentially passes through the half-wave plate 1 and the polaroid 2 to adjust energy, the femtosecond laser pulse after the energy adjustment passes through the first quarter-wave plate 3 to convert the polarization state of the femtosecond laser pulse into circular polarization from linear polarization, then passes through the vortex wave plate 4 to convert the circularly polarized femtosecond laser pulse into a circularly polarized femtosecond vortex beam, and then passes through the second quarter-wave plate 5 to modulate the circularly polarized femtosecond vortex beam into the linearly polarized femtosecond vortex beam.
The fluorescence collecting device comprises a collecting lens 7, an optical filter 8, a photomultiplier tube 9 and an oscilloscope 10, wherein the optical filter 8 comprises a band-pass optical filter and an ultraviolet-transmitting low-pass optical filter which are arranged on the same optical axis; the collecting lens 7 is used for collecting lateral fluorescent signals of the femtosecond vortex light beams, the lateral fluorescent signals enter the photomultiplier tube 9 through the band-pass filter and the ultraviolet-transmitting low-pass filter, and the oscilloscope 10 is used for monitoring and recording the intensity of the lateral fluorescent signals.
The center wavelength of the band pass filter is determined according to the gas medium, in the embodiment, the femtosecond vortex beam self-focusing critical power measuring system is used in the air, the center wavelength of the band pass filter is 337nm (the fluorescence spectrum line of 337nm is from nitrogen in the air), the focal length of the focusing lens 6 is 50cm, the focal length of the collecting lens 7 is 75mm, and the femtosecond laser pulse is generated by a titanium-doped sapphire chirped pulse amplification laser system with the center wavelength of 800nm, the repetition frequency of 1kHz and the pulse width of 65 fs.
The working principle of the embodiment is as follows:
the titanium sapphire chirped pulse amplification laser system with the central wavelength of 800nm, the repetition frequency of 1kHz and the pulse width of 65fs generates femtosecond laser pulses, the femtosecond laser pulses are incident to the half-wave plate 1, the half-wave plate 1 changes the polarization direction of the incident femtosecond laser pulses, and the included angle between the polarization direction of the femtosecond laser pulses incident to the polaroid 2 and the polarization direction which can be penetrated by the polaroid 2 is adjusted by rotating the half-wave plate 1, namely the energy of the femtosecond laser pulses is adjusted.
The femtosecond laser pulse after energy adjustment is incident to the first quarter wave plate 3, the first quarter wave plate 3 converts the linearly polarized femtosecond laser pulse into a circularly polarized femtosecond laser pulse, the circularly polarized femtosecond laser pulse is incident to the vortex wave plate 4, the vortex wave plate 4 modulates the circularly polarized femtosecond laser pulse into a circularly polarized femtosecond vortex beam, the circularly polarized femtosecond vortex beam is incident to the second quarter wave plate 5, and the second quarter wave plate 5 modulates the circularly polarized femtosecond vortex beam into a linearly polarized femtosecond vortex beam; the linearly polarized femtosecond vortex beam passes through the focusing lens 6, and the focusing lens 6 focuses and ionizes air in the air when the femtosecond vortex beam passes through, so that a plasma filament is generated.
Collecting lens 7 collects the side direction fluorescence signal of femto second vortex light beam, side direction fluorescence signal incides band pass filter, the fluorescence spectrum of nitrogen gas in the band pass filter filtered air, the side direction fluorescence signal that the band pass filter was filterable incides the ultraviolet low pass filter, the ultraviolet low pass filter further filters stray light such as the fundamental frequency in the environment, side direction fluorescence signal after the filtration gets into photomultiplier 9, photomultiplier 9 converts side direction fluorescence signal into the signal of telecommunication, photomultiplier 9's signal uses oscilloscope 10 to monitor and record.
The femtosecond laser pulse energy is continuously adjusted from small to large through the matching of the half-wave plate 1 and the polaroid 2, corresponding electric signals are recorded, linear fitting is carried out according to the change trend of the signal intensity to find out the mutation position of the signal intensity change, and the self-focusing critical power of the femtosecond vortex light beam is obtained from the intersection point of a fitting line.
In some embodiments, the circularly polarized femtosecond vortex beam can be directly measured, and in this case, the vortex beam generation device comprises a first quarter wave plate 3, a vortex wave plate 4 and a focusing lens 6.
The femtosecond laser pulse after energy adjustment is incident to the first quarter wave plate 3, the linearly polarized femtosecond laser pulse is converted into a circularly polarized femtosecond laser pulse by the first quarter wave plate 3, the circularly polarized femtosecond laser pulse is incident to the vortex wave plate 4, the vortex wave plate 4 modulates the circularly polarized femtosecond laser pulse into a circularly polarized femtosecond vortex light beam, the circularly polarized femtosecond vortex light beam passes through the focusing lens 6, and the focusing lens 6 focuses and ionizes air in the air when the femtosecond vortex light beam passes through, so that a plasma filament is generated.
Example two
With reference to fig. 2-3, this embodiment discloses a method for measuring the femtosecond vortex beam self-focusing critical power, which includes the following steps:
step 1, performing self-inspection on each device in a femtosecond vortex beam self-focusing critical power measuring system, and executing step 2 if the self-inspection is normal;
Specifically, the angle of the half-wave plate 1 is adjusted, the included angle between the half-wave plate 1 and the polaroid 2 is changed, the femtosecond laser pulse energy is continuously adjusted from small to large under the matching of the half-wave plate 1 and the polaroid 2, in the process of continuous adjustment, the adjusted femtosecond laser pulse is incident to the vortex beam generating device, and the following steps are executed until the last step is finished.
And 4, collecting the lateral fluorescent signals of the femtosecond vortex light beams by a collecting lens 7 with the focal length of 75mm, enabling the lateral fluorescent signals to sequentially pass through a band-pass filter and an ultraviolet-transmitting low-pass filter to enter a photomultiplier tube 9, and converting the lateral fluorescent signals into electric signals by the photomultiplier tube 9 and transmitting the electric signals to an oscilloscope 10 for monitoring and recording.
And 5, recording the femtosecond laser pulses with different energies and the signal intensity of the corresponding lateral fluorescent signal, performing linear fitting according to the change trend of the signal intensity to find out the mutation position of the signal intensity change, and obtaining the self-focusing critical power of the femtosecond vortex beam from the intersection point of a fitting line.
Specifically, taking femtosecond vortex beams with topological charges of 1, 2 and 3 as an example, a relationship graph shown in fig. 3 is drawn according to the signal intensity of the lateral fluorescent signal and the energy of the corresponding femtosecond laser pulse recorded by the oscilloscope 10, when the energy of the femtosecond laser pulse is very small, the signal intensity of the lateral fluorescent signal is almost unchanged, and as the energy is increased, the fluorescent intensity is rapidly increased at higher laser power, and obvious intensity changes occur at about 200 μ J, 340 μ J and 380 μ J respectively, that is, more laser energy is needed to excite the nonlinear increase of the fluorescent intensity, and the strong intensity change means that the self-focusing critical power should be within this range, and a linear fitting method is adopted to find the self-focusing critical power of the vortex beam. As shown in fig. 3, the intersection points of the linear fit lines are located at 230.71 μ J, 410.66 μ J and 512.71 μ J, respectively, which correspond to 3.55GW, 6.32GW, and 7.89GW of the vortex beam of topological charge m =1, 2, and 3, respectively. Furthermore, this can also result in that the critical power for the self-focusing of the vortex beam increases with increasing topological charge.
In the foregoing embodiments, the descriptions of the embodiments have different emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A femtosecond vortex beam self-focusing critical power measuring system is characterized by comprising:
a femtosecond laser output energy adjusting device for adjusting energy of incident femtosecond laser pulses;
the vortex beam generating device is used for converting the femtosecond laser pulse after the energy is adjusted into a femtosecond vortex beam and generating a plasma filament; and the number of the first and second groups,
a fluorescence collection device for collecting and monitoring lateral fluorescence signals of the femtosecond vortex beam.
2. The femtosecond vortex beam self-focusing critical power measuring system as claimed in claim 1, wherein the femtosecond laser output energy adjusting device comprises a half-wave plate and a polarizing plate which are sequentially arranged on the same optical axis, the femtosecond laser pulse sequentially passes through the half-wave plate and the polarizing plate, and the included angle between the half-wave plate and the polarizing plate is changed by rotating the angle of the half-wave plate, so as to realize continuous adjustment of the energy of the input femtosecond laser pulse.
3. The femtosecond vortex beam self-focusing critical power measuring system as claimed in claim 1, wherein the vortex beam generating device comprises a first quarter wave plate, a vortex wave plate and a focusing lens which are sequentially arranged on the same optical axis;
the first quarter wave plate is used for converting the polarization state of the femtosecond laser pulse from linear polarization to circular polarization;
the vortex wave plate is used for converting the circularly polarized femtosecond laser pulse into a circularly polarized femtosecond vortex light beam;
the focusing lens is used for focusing ionized air in the air when the femtosecond vortex light beam passes through the focusing lens to generate plasma filaments;
further, the vortex light beam generating device also comprises a second quarter wave plate arranged between the vortex wave plate and the focusing lens;
the second quarter-wave plate is used for modulating the circularly polarized femtosecond vortex beam into a linearly polarized femtosecond vortex beam.
4. The femtosecond vortex beam self-focusing critical power measurement system according to claim 1, wherein the fluorescence collection device comprises a collection lens, an optical filter, a photomultiplier tube and an oscilloscope;
the collecting lens is used for collecting lateral fluorescent signals of the femtosecond vortex light beams, the lateral fluorescent signals enter the photomultiplier through the optical filter, and the oscilloscope is used for monitoring and recording the intensity of the lateral fluorescent signals.
5. The femtosecond vortex beam self-focusing critical power measuring system according to claim 4, wherein the optical filter comprises a band-pass filter and an ultraviolet-transmitting low-pass filter which are sequentially arranged on the same optical axis, the band-pass filter is used for filtering fluorescence spectrum in gas medium, and the ultraviolet-transmitting low-pass filter is used for filtering stray light in environment.
6. A femtosecond vortex beam self-focusing critical power measuring method which can adopt the femtosecond vortex beam self-focusing critical power measuring system according to any one of claims 1 to 5, and is characterized by comprising the following steps:
step 1, starting a femtosecond laser to generate femtosecond laser pulses, wherein the femtosecond laser pulses enter a femtosecond laser output energy adjusting device to obtain femtosecond laser pulses with adjusted energy;
step 2, enabling the femtosecond laser pulse after energy adjustment to enter a vortex beam generating device to generate a femtosecond vortex beam and a plasma filament;
step 3, collecting and monitoring lateral fluorescent signals of the femtosecond vortex light beams by a fluorescent collecting device;
and 4, recording femtosecond laser pulses with different energies and signal intensity of corresponding lateral fluorescent signals, and calculating the self-focusing critical power of the femtosecond vortex beam according to the variation trend of the signal intensity.
7. The method for measuring the critical power of the femtosecond vortex beam self-focusing as claimed in claim 6, wherein the angle between the half-wave plate and the polarizer is changed by adjusting the angle of the half-wave plate, so as to continuously adjust the energy of the input femtosecond laser pulse.
8. The method for measuring the critical power of the femtosecond vortex beam self-focusing according to claim 6, wherein the femtosecond laser pulse after energy adjustment sequentially passes through the first quarter wave plate, the vortex wave plate and the second quarter wave plate to generate the femtosecond vortex beam; the femtosecond vortex beam passes through a focusing lens to focus ionized air in the air, and plasma filaments are generated.
9. The method for measuring critical power of femtosecond vortex beam self-focusing as claimed in claim 6, wherein the collecting lens collects the lateral fluorescence signal of the femtosecond vortex beam, the lateral fluorescence signal sequentially passes through the band-pass filter and the ultraviolet-transmitting low-pass filter to enter the photomultiplier tube, and the photomultiplier tube converts the lateral fluorescence signal into an electrical signal and transmits the electrical signal to the oscilloscope for monitoring and recording.
10. The femtosecond vortex beam self-focusing critical power measurement method according to claim 6, wherein the femtosecond laser pulse is generated by a femtosecond laser amplifier with a center wavelength of 800nm, a pulse duration of 65fs, a repetition frequency of 1kHz, and a maximum pulse capability of 6mJ.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211582130.1A CN115855280A (en) | 2022-12-09 | 2022-12-09 | Femtosecond vortex beam self-focusing critical power measuring method and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211582130.1A CN115855280A (en) | 2022-12-09 | 2022-12-09 | Femtosecond vortex beam self-focusing critical power measuring method and system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115855280A true CN115855280A (en) | 2023-03-28 |
Family
ID=85671712
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211582130.1A Pending CN115855280A (en) | 2022-12-09 | 2022-12-09 | Femtosecond vortex beam self-focusing critical power measuring method and system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115855280A (en) |
-
2022
- 2022-12-09 CN CN202211582130.1A patent/CN115855280A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Auston | Subpicosecond electro‐optic shock waves | |
| CN103487887B (en) | A kind of different wave length multi-pass Laser synthesizing and transmitting device and using method thereof | |
| Ramirez et al. | Efficient cross polarized wave generation for compact, energy-scalable, ultrashort laser sources | |
| CN106099624B (en) | The system and method that laser excitation air plasma generates high intensity THz wave | |
| CN101271025A (en) | Method and device for ultrafast time discrimination measurement of seed photo-signal | |
| CN105470796B (en) | Infrared super continuum source in a kind of high brightness ultra wide band | |
| Fabris et al. | Single-shot implementation of dispersion-scan for the characterization of ultrashort laser pulses | |
| Romero et al. | Diffractive optics for spectral control of the supercontinuum generated in sapphire with femtosecond pulses | |
| CN103944048A (en) | Femtosecond laser device based on single cladding neodymium optical fibers and ring cavity and manufacturing method | |
| Langer et al. | Few-cycle lightwave-driven currents in a semiconductor at high repetition rate | |
| CN102540328A (en) | Photonic crystal fiber, THz wave parametric oscillation generating system and method | |
| Ye et al. | High-flux 100 kHz attosecond pulse source driven by a high-average power annular laser beam | |
| CN202141673U (en) | Absorption spectrum detection system | |
| CN111220573A (en) | Nonlinear optical absorption cross section measuring method | |
| CN110323663A (en) | The apparatus and method of the vector ultrashort laser pulse of infrared band in a kind of generation | |
| WANG et al. | Advances in terahertz three-dimensional imaging techniques | |
| CN115855280A (en) | Femtosecond vortex beam self-focusing critical power measuring method and system | |
| CN100576050C (en) | The mercuric bromide crystal is as the application of infrared band nonlinear optical material | |
| CN105790045A (en) | High-energy few-cycle ultra-high-signal to noise ratio femtosecond seed pulse generation device | |
| Yuan et al. | Enhanced nonlinearity for filamentation in gold-nanoparticle-doped water | |
| Wang et al. | Generation of high-energy clean multicolored ultrashort pulses and their application in single-shot temporal contrast measurement | |
| CN111934165B (en) | Ultrashort pulse generation method based on flight focus and plasma back Raman scattering | |
| Feng et al. | Supercontinuum generated by a femtosecond annular Gaussian beam in air | |
| CN110596073B (en) | Total reflection type femtosecond stimulated Raman spectrometer | |
| JPH05173217A (en) | Second optical harmonic wave generator |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |