CN204424679U - Infrared femtosecond laser and parametric amplifier thereof in one - Google Patents

Abstract

The utility model relates to infrared femtosecond laser and parametric amplifier thereof in one, it comprises: OPA femtosecond pump laser, flashlight light source, on the exit channel being arranged on OPA femtosecond pump laser and flashlight light source and for the device of the set of wavelengths beam function that superposes pump light that OPA femtosecond pump laser sends and the flashlight that flashlight light source sends, and transform for the pump light after superposition and flashlight being carried out the periodic polarized quadratic nonlinearity crystal exporting ideler frequency light, structure is simple, cost is low, modulation is simple, environment resistant interference performance is strong, high optical quality exports, high transformation efficiency, high repetition frequency, be beneficial to miniaturization and portability.

Description

Infrared femtosecond laser and parametric amplifier thereof in one

Technical field

The utility model relates to field of laser device technology, infrared femtosecond laser and parametric amplifier thereof specifically.

Background technology

Middle infrared femtosecond laser has a wide range of applications in fields such as imaging of medical, biological medicine monitoring, atmospheric monitoring, infrared radar, infrared laser guidance and celestial body detections.The method of current generation infrared femtosecond laser mainly contains two kinds, is respectively parametric oscillation (OPO) and parameter amplification (OPA).Both utilize quadratic nonlinearity principle, on the basis meeting phase matched, produce mid-infrared laser by difference on the frequency point-score, its frequency inverted formula is λ _pfor pump wavelength, λ _sfor signal light wavelength, λ _ifor ideler frequency optical wavelength.

At present based on infrared femtosecond laser in OPO and OPA, complex structure, involves great expense, and modulation difficulty is high.The performance of laser is at wavelength cover simultaneously, power output, repetition rate, aspect all existing defects such as environment resistant interference performance.

OPO principle laser utilizes internal oscillation principle, excites the spontaneous radiation effect of quadratic nonlinearity crystal.Its system configuration is high to resonant cavity required precision, and thus cause environment resistant interference performance poor, humidity, the environmental changes such as temperature all can cause the sharp-decay of power output.Simultaneously owing to adopting spontaneous radiation principle, the middle infrared laser of current OPO is defeated, and on average to go out power be tens milliwatts, cannot meet practical application request.

OPA principle laser adopts the pouring-in method of mixing, the difference frequency effect in quadratic nonlinearity crystal by pump light and flashlight, infrared ideler frequency light in generation.But the inverse conversion effect that can occur between pump light and flashlight in parametric amplification, heavy damage exports time domain waveform and the coherence of light.For keeping the optical quality exporting light, traditional OPA needs conversion efficiency to be compressed on lower level, about 5% ~ 10%, increases conversion efficiency further, will cause " inverse conversion effect ", destroys and exports light optical quality.In order to improve power output, current OPA system many employings secondary or multistage amplifying technique, considerably increase system cost and complexity, causes modulation difficulty to promote simultaneously.

In the multistage amplifying technique of OPA, in order to ensure pump light and flashlight Domain Synchronous, also need to add phase delay assembly before every grade of amplification, this is promoting complexity further and while modulating difficulty, is also seriously limiting the repetition rate of OPA system.Current multistage OPA system repetition rate is stuck in 1000Hz ~ 10KHz, limits signal sampling density, causes in its practical application limited.Multistage amplification simultaneously and phase delay assembly also reduce the environment resistant interference performance of OPA system, add system scale, are unfavorable for portable package.

Utility model content

Main purpose of the present utility model is to provide infrared femtosecond laser and parametric amplifier thereof in one, and structure is simple, and cost is low, modulation is simple, and environment resistant interference performance is strong, and high optical quality exports, high transformation efficiency, high repetition frequency, is beneficial to miniaturization and portability.

The utility model solves the technical scheme that its technical problem adopts:

Infrared femtosecond parametric amplifier in one, it comprises: OPA femtosecond pump laser 1, flashlight light source 5, be arranged on OPA femtosecond pump laser 1 and flashlight light source 5 exit channel on and for the set of wavelengths beam function that superposes pump light that OPA femtosecond pump laser 1 sends and the flashlight that flashlight light source 5 sends device 10, transform for the pump light after superposition and flashlight being carried out the periodic polarized quadratic nonlinearity crystal 11 exporting ideler frequency light, wherein:

Pump wavelength, signal light wavelength, ideler frequency optical wavelength demand fulfillment quadratic nonlinearity difference frequency process medium frequency conversion formula (1) are: λ _p, λ _s, λ _ibe respectively the frequency of pump light, flashlight, ideler frequency light;

Refractive Index of Material according to pump wavelength, signal light wavelength, ideler frequency optical wavelength and periodic polarized quadratic nonlinearity crystal determines the Crystal polarization cycle, and its formula (2) determined is: wherein n _p, n _s, n _ibe respectively pump light, flashlight, Refractive Index of Material that ideler frequency light is corresponding, m is quasi-phase matched progression, and Λ is polarization cycle;

The Refractive Index of Material of pump light, flashlight, ideler frequency light and periodic polarized quadratic nonlinearity crystal must meet material dispersion condition, and formula (3) is as follows:

$(n_i-n_p)(n_s-n_p)+n_s{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}+n_p{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{{\&PartialD;\mathrm{\&lambda;}}_i}<......$

$(n_i-n_p)({\mathrm{\&lambda;}}_s\frac{{\&PartialD;n}_s}{{\&PartialD;\mathrm{\&lambda;}}_s}-{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p})+n_s{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{{\&PartialD;\mathrm{\&lambda;}}_i}+n_p{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}+.......$

$({\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}-{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{{\&PartialD;\mathrm{\&lambda;}}_i})({\mathrm{\&lambda;}}_s\frac{{\&PartialD;n}_s}{{\&PartialD;\mathrm{\&lambda;}}_s}-{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p})$

Wherein: represent n _xto λ _xfirst derivation, wherein, x is i, s, or p.

Preferably, the device 10 of described set of wavelengths beam function is: dichronic mirror, spectro-grating or Amici prism.

Preferably, also comprise: the first half-wave plate 2, described first half-wave plate 2 is arranged between OPA femtosecond pump laser 1 and periodic polarized quadratic nonlinearity crystal 11.

Preferably, also comprise: the first optical isolator 3, described first optical isolator 3 is arranged on the emitting light path of described OPA femtosecond pump laser 1.

Preferably, also comprise: the first beam spot controller 4, described first beam spot controller 4 is arranged between OPA femtosecond pump laser 1 and periodic polarized quadratic nonlinearity crystal 11.

Preferably, also comprise: the second half-wave plate 6, described second half-wave plate 6 is arranged on the emitting light path of flashlight light source 5.

Preferably, also comprise: the second optical isolator 7, described second optical isolator 7 is arranged on the emitting light path of flashlight light source 5.

Preferably, also comprise: the second beam spot controller 8, described second beam spot controller 8 is arranged between flashlight light source 5 and periodic polarized quadratic nonlinearity crystal 11.

Preferably, also comprise: the first reflective mirror 9, described first reflective mirror 9 is arranged on the emitting light path of flashlight light source 5.

Preferably, also comprise: the second reflective mirror 12, described second reflective mirror 12 is arranged on the emitting light path of periodic polarized quadratic nonlinearity crystal 11.

Preferably, also comprise: middle infrared filter 13, described middle infrared filter 13 is arranged on the emitting light path of periodic polarized quadratic nonlinearity crystal 11.

The utility model embodiment also provides infrared femtosecond laser in one, comprises the middle infrared femtosecond parametric amplifier described in above-mentioned arbitrary technical scheme.

Implement the technical solution of the utility model, there is following beneficial effect: the middle infrared femtosecond laser that the utility model provides and parametric amplifier thereof, by an OPA femtosecond pump laser, a flashlight light source and one-period polarization quadratic nonlinearity crystal realize one-level OPA amplifying technique, pump light simultaneously, flashlight, the Refractive Index of Material of ideler frequency light and periodic polarized quadratic nonlinearity crystal must meet the material dispersion condition of formula (3) to realize dispersion phase delay technology, successfully inhibit " the inverse conversion effect " in OPA, while maintenance exports light high optical quality, the conversion efficiency of 50% ~ 80% is achieved in one-level OPA amplifies.Effectively improve the power output of OPA system.

In this, the Resonator design of OPO abandoned by infrared femtosecond laser and parametric amplifier thereof.Dispersion phase delay technology effectively can improve conversion efficiency, makes one-level OPA system just can reach the power demand of practical application, avoids secondary or multi-stage amplifier system, effectively reduce the complexity of OPA system, cost, and modulation difficulty.

In this, infrared femtosecond laser and parametric amplifier thereof improve environment resistant interference performance based on the one-level OPA system pole of dispersion phase delay technology.

In this, infrared femtosecond laser and parametric amplifier thereof eliminate multistage OPA system to the restriction of repetition rate based on the one-level OPA system of dispersion phase delay technology, make repetition rate can reach the even higher repetition rate of 20MHz ~ 80HMz.

In this, infrared femtosecond laser and parametric amplifier thereof are based on the one-level OPA system of dispersion phase delay technology, because system construction is simple, can accomplish miniaturized and portable advantage.

In this, infrared femtosecond laser and the applicable wavelength band of parametric amplifier dispersion phase delay technology thereof are wide, everyly meet the periodic polarized quadratic nonlinearity crystal that material dispersion condition { comprises formula (3) } and all can use this dispersion phase delay technology.

In this, the dispersion phase delay technology of infrared femtosecond laser and parametric amplifier thereof not only can realize single-stage OPA high optical quality, and high efficiency exports, and also has compression pulse time domain width function, improves the time-domain coherence exporting pulse further.

In this, infrared femtosecond laser and parametric amplifier dispersion phase delay technology thereof are not only applicable to femtosecond pulse, and its theory and design structure can be applied to picosecond pulse laser.Range of application is wide.

Accompanying drawing explanation

Fig. 1 for the utility model embodiment provide in the structural representation of infrared femtosecond parametric amplifier first embodiment;

Fig. 2 for the utility model embodiment provide in the structural representation of infrared femtosecond parametric amplifier second embodiment;

Fig. 3 for the utility model embodiment provide in infrared femtosecond parametric amplifier and prior art export the comparison diagram of ideler frequency light;

Fig. 4 for the utility model embodiment provide in the structural representation of infrared femtosecond parametric amplifier the 3rd embodiment.

The realization of the utility model object, functional characteristics and advantage will in conjunction with the embodiments, are described further with reference to accompanying drawing.

Embodiment

In order to make the purpose of this utility model, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the utility model is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the utility model, and be not used in restriction the utility model.

The utility model embodiment provides infrared femtosecond parametric amplifier in one, it is characterized in that, comprise: OPA femtosecond pump laser 1, flashlight light source 5, on the exit channel being arranged on OPA femtosecond pump laser 1 and flashlight light source 5 and for the device 10 of the set of wavelengths beam function that superposes pump light that OPA femtosecond pump laser 1 sends and the flashlight that flashlight light source 5 sends, the periodic polarized quadratic nonlinearity crystal 11 exporting ideler frequency light is transformed for the pump light after superposition and flashlight being carried out, flashlight light source 5 adopts continuous laser, continuous laser can keep pump light and flashlight Domain Synchronous, be applicable to high repetition frequency system.As shown in Figure 4, flashlight light source 5 also can adopt pulse laser to replace continuous laser, selects according to demand whether to add phase delaying device, wherein:

Pump wavelength, signal light wavelength, ideler frequency optical wavelength demand fulfillment quadratic nonlinearity difference frequency process medium frequency conversion formula (1) are: λ _p, λ _s, λ _ibe respectively the frequency of pump light, flashlight, ideler frequency light;

Refractive Index of Material according to pump wavelength, signal light wavelength, ideler frequency optical wavelength and periodic polarized quadratic nonlinearity crystal determines the Crystal polarization cycle, and its formula (2) determined is: wherein n _p, n _s, n _ibe respectively pump light, flashlight, Refractive Index of Material that ideler frequency light is corresponding, m is quasi-phase matched progression, and Λ is polarization cycle;

The Refractive Index of Material of pump light, flashlight, ideler frequency light and periodic polarized quadratic nonlinearity crystal must meet material dispersion condition, and formula (3) is as follows:

$(n_i-n_p)(n_s-n_p)+n_s{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}+n_p{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{{\&PartialD;\mathrm{\&lambda;}}_i}<......$

$(n_i-n_p)({\mathrm{\&lambda;}}_s\frac{{\&PartialD;n}_s}{{\&PartialD;\mathrm{\&lambda;}}_s}-{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p})+n_s{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{{\&PartialD;\mathrm{\&lambda;}}_i}+n_p{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}+.......$

$({\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}-{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{{\&PartialD;\mathrm{\&lambda;}}_i})({\mathrm{\&lambda;}}_s\frac{{\&PartialD;n}_s}{{\&PartialD;\mathrm{\&lambda;}}_s}-{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p})$

Wherein: represent n _xto λ _xfirst derivation, wherein, x is i, s, or p.After material dispersion condition meets, in parametric amplification: pump light, flashlight, ideler frequency light can be separated in time domain.Pump light after separation, flashlight and ideler frequency light stop interacting, thus inhibit inverse conversion effect, maintain the optical quality of the ideler frequency light of high-caliber output, achieve high conversion efficiency OPA.

The parametric amplifier that above-described embodiment provides achieves high conversion efficiency parameter and amplifies, can infrared ideler frequency light in output high-power.

The application example of above-described embodiment.Pump laser is Yb femto-second laser, and wavelength is 1041nm, pulse duration 500fs, repetition rate 21MHz.Flashlight adopts 1398nm continuous laser.4073nm ideler frequency light is produced after difference frequency.Period polarized quadratic nonlinearity crystal can adopt as periodic polarized lithium niobate (PPLN).When after the material dispersion condition that periodic polarized quadratic nonlinearity crystal satisfies condition in formula (3), pump light, flashlight and ideler frequency light are separated in time domain, inhibit " inverse conversion effect ", export light and keep high optical quality, conversion efficiency is 75%.The pulse duration of ideler frequency light achieves time domain data compression by dispersion phase delay technology simultaneously, shortens to 350fs.Ideler frequency light repetition rate is determined by pump light, is 21MHz.Ideler frequency light average output power is 200mW.Thus achieve high optical quality, high repetition frequency, high conversion efficiency, the middle infrared parametric amplifier of high-power output.

Fig. 3 is under the same terms, meet above-mentioned material dispersion conditions and do not meet above-mentioned material dispersion conditions output ideler frequency light contrast.Using under the condition in above-described embodiment, ideler frequency light keeps high-quality time domain waveform, and does not adopt the time domain waveform heavy damage of the ideler frequency light of volume condition in above-described embodiment.Above-described embodiment goes for psec OPA system equally.

In the above-described embodiments, preferably, the device 10 of described set of wavelengths beam function is: dichronic mirror, spectro-grating or Amici prism.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: the first half-wave plate 2, and described first half-wave plate 2 is arranged between OPA femtosecond pump laser 1 and periodic polarized quadratic nonlinearity crystal 11.If the pump light volume polarization state that OPA femtosecond pump laser 1 sends is not mated with periodic polarized quadratic nonlinearity crystal 11, regulated the degree of polarization of pump light by the first half-wave plate 2, OPA femtosecond pump laser 1 and periodic polarized quadratic nonlinearity crystal 11 are mated in polarization state.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: the first optical isolator 3, and described first optical isolator 3 is arranged on the emitting light path of described OPA femtosecond pump laser 1.If pump light is through the device 10 of set of wavelengths beam function, produce strong reflection during periodic polarized quadratic nonlinearity crystal 11, can eliminate by interpolation the first optical isolator 3 OPA femtosecond pump laser 1 after the harmful effect that reverberation causes pump light.First optical isolator 3 can be made up of two polarizers and a quarter-wave plate, also can adopt other types optical isolator.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: the first beam spot controller 4, and described first beam spot controller 4 is arranged between OPA femtosecond pump laser 1 and periodic polarized quadratic nonlinearity crystal 11.If the optical strength of OPA femtosecond pump laser 1 volume pump light in periodic polarized quadratic nonlinearity crystal 11 is not enough, or too high, pump light optical strength can be regulated by the first beam spot controller 4.First beam spot controller 4 can be made up of concavees lens and convex lens, also can adopt other types beam spot controller.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: the second half-wave plate 6, and described second half-wave plate 6 is arranged on the emitting light path of flashlight light source 5.If the polarization state of the flashlight of flashlight light source 5 is not mated with OPA femtosecond pump laser 1, periodic polarized quadratic nonlinearity crystal 11, by adding the second half-wave plate 6 based on signal light wavelength after flashlight light source 5, the flashlight polarization state of conditioning signal radiant 5 can be carried out.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: the second optical isolator 7, and described second optical isolator 7 is arranged on the emitting light path of flashlight light source 5.If flashlight causes strong reflection when the device 10 of set of wavelengths beam function, periodic polarized quadratic nonlinearity crystal 11, reverberation can be eliminated by adding after flashlight light source 5 based on the second optical isolator 7 of signal light wavelength.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: the second beam spot controller 8, and described second beam spot controller 8 is arranged between flashlight light source 5 and periodic polarized quadratic nonlinearity crystal 11.If the flashlight of flashlight light source 5 optical strength in periodic polarized quadratic nonlinearity crystal 11 is undesirable, can by adding the second beam spot controller 8 between flashlight light source 5 and periodic polarized quadratic nonlinearity crystal 11, with conditioning signal light light intensity.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: the first reflective mirror 9, and described first reflective mirror 9 is arranged on the emitting light path of flashlight light source 5.If the transmission direction of flashlight light source 5 is unfavorable for that same OPA femtosecond pump laser 1 superposes, interpolation first reflective mirror 9 conditioning signal optical transmission direction can be passed through.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: the second reflective mirror 12, and described second reflective mirror 12 is arranged on the emitting light path of periodic polarized quadratic nonlinearity crystal 11.If transmission direction and the optics divergence of the ideler frequency light exported through periodic polarized quadratic nonlinearity crystal 11 are undesirable, ideler frequency optical transmission direction and the optics divergence of regulation output can be come by interpolation the second reflective mirror 12 periodic polarized quadratic nonlinearity crystal 11 after.

In other embodiments, on the various embodiments described above basis, this parametric amplifier also comprises: middle infrared filter 13, and described middle infrared filter 13 is arranged on the emitting light path of periodic polarized quadratic nonlinearity crystal 11.If need by infrared ideler frequency light separate from pump light and flashlight, in can adding after periodic polarized quadratic nonlinearity crystal 11, infrared filter 13 eliminates pump light and flashlight.Also similar effect can be reached as crossed use Amici prism.

The utility model embodiment also provides infrared femtosecond laser in one, comprises the middle infrared femtosecond parametric amplifier described in above-mentioned any embodiment.

Above embodiment is only preferred embodiment of the present utility model; not in order to limit the utility model; all do within spirit of the present utility model and principle any amendment, equivalent to replace and improvement etc., all should be included within protection range of the present utility model.

Claims (10)

1. infrared femtosecond parametric amplifier in a kind, it is characterized in that, comprise: OPA femtosecond pump laser (1), flashlight light source (5), be arranged on OPA femtosecond pump laser (1) and flashlight light source (5) exit channel on and for the set of wavelengths beam function that superposes pump light that OPA femtosecond pump laser (1) sends and the flashlight that flashlight light source (5) sends device (10), transform for the pump light after superposition and flashlight being carried out the periodic polarized quadratic nonlinearity crystal (11) exporting ideler frequency light, wherein:

Pump wavelength, signal light wavelength, ideler frequency optical wavelength demand fulfillment quadratic nonlinearity difference frequency process medium frequency conversion formula (1) are: λ _p, λ _s, λ _ibe respectively the frequency of pump light, flashlight, ideler frequency light;

Refractive Index of Material according to pump wavelength, signal light wavelength, ideler frequency optical wavelength and periodic polarized quadratic nonlinearity crystal determines the Crystal polarization cycle, and its formula (2) determined is: wherein n _p, n _s, n _ibe respectively pump light, flashlight, Refractive Index of Material that ideler frequency light is corresponding, m is quasi-phase matched progression, and Λ is polarization cycle;

The refractive index of pump light, flashlight, ideler frequency light and periodic polarized quadratic nonlinearity crystal must meet material dispersion condition, and formula (3) is as follows:

$\begin{array}{c}(n_i-n_p)(n_s-n_p)+n_s{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}+n_p{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{{\&PartialD;\mathrm{\&lambda;}}_i}<......\\ (n_i-n_p)({\mathrm{\&lambda;}}_s\frac{{\&PartialD;n}_s}{{\&PartialD;\mathrm{\&lambda;}}_p}-{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p})+n_s{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{{\&PartialD;\mathrm{\&lambda;}}_i}+n_p{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}\\ ({\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p}-{\mathrm{\&lambda;}}_i\frac{{\&PartialD;n}_i}{\&PartialD;{\mathrm{\&lambda;}}_i})({\mathrm{\&lambda;}}_s\frac{{\&PartialD;n}_s}{{\&PartialD;\mathrm{\&lambda;}}_s}-{\mathrm{\&lambda;}}_p\frac{{\&PartialD;n}_p}{{\&PartialD;\mathrm{\&lambda;}}_p})\end{array},+......$

Wherein: represent n _xto λ _xfirst derivation, wherein, x is i, s, or p.

2. as claimed in claim 1 in infrared femtosecond parametric amplifier, it is characterized in that, the device (10) of described set of wavelengths beam function is: dichronic mirror, spectro-grating or Amici prism.

3. as claimed in claim 2 in infrared femtosecond parametric amplifier, it is characterized in that, also comprise: the first half-wave plate (2), described first half-wave plate (2) is arranged between OPA femtosecond pump laser (1) and periodic polarized quadratic nonlinearity crystal (11).

4. as claimed in claim 2 in infrared femtosecond parametric amplifier, it is characterized in that, also comprise: the first optical isolator (3), described first optical isolator (3) is arranged on the emitting light path of described OPA femtosecond pump laser (1).

5. as claimed in claim 2 in infrared femtosecond parametric amplifier, it is characterized in that, also comprise: the first beam spot controller (4), described first beam spot controller (4) is arranged between OPA femtosecond pump laser (1) and periodic polarized quadratic nonlinearity crystal (11).

6. as claimed in claim 2 in infrared femtosecond parametric amplifier, it is characterized in that, also comprise: the second half-wave plate (6), described second half-wave plate (6) is arranged on the emitting light path of flashlight light source (5).

7. as claimed in claim 2 in infrared femtosecond parametric amplifier, it is characterized in that, also comprise: the second beam spot controller (8), described second beam spot controller (8) is arranged between flashlight light source (5) and periodic polarized quadratic nonlinearity crystal (11).

8. as claimed in claim 2 in infrared femtosecond parametric amplifier, it is characterized in that, also comprise: the second reflective mirror (12), described second reflective mirror (12) is arranged on the emitting light path of periodic polarized quadratic nonlinearity crystal (11).

9. as claimed in claim 2 in infrared femtosecond parametric amplifier, it is characterized in that, also comprise: middle infrared filter (13), described middle infrared filter (13) is arranged on the emitting light path of periodic polarized quadratic nonlinearity crystal (11).

10. in, an infrared femtosecond laser, is characterized in that, comprises the middle infrared femtosecond parametric amplifier described in above-mentioned arbitrary claim.