CN1108010C - Optical parametric amplifier - Google Patents

Abstract

The present invention relates to an optical parametric amplifier which comprises an amplifying element which is composed of non-linear crystals. A laser is used as a signal light source and a pumping light source which are provided with the same synchronous controller. The light intensity (Ip) of pumping light (Gp) is greater than the light intensity (Is) of signal light (Gs); the wavelength (lambda <p>) of the pumping light (Gp) is less than the wavelength (lambda <s>) of the signal light (Gs). An optical axis (O1) of the signal light (Gs) is perpendicular to an incidence plane of the amplifying element and forms an included angle (alpha) with an optical axis (O2) of the pumping light (Gp), and the included angle (alpha) is not equal to zero. A phase matching angle (thet) of the signal light (Gs) between a propagation direction in the amplifying element and a direction of an optical axis of the crystal is not equal to zero, wherein the direction of the optical axis of the crystal forms the amplifying element. The amplifying device of the present invention can make the light intensity (Is) of the weak signal light (Gs) be amplified by more than one thousand times.

Description

Optical parametric amplifier

Technical field:

The present invention is a kind of optical parametric amplifier.Be mainly used to amplify the light intensity of weak optical signal.

Background technology:

Britain I.N. Luo Si people such as (I.N.Ross) has discussed amplification process and the theory about optical parameter in the prior art in " optical parameter chirped pulse amplification principle and feasibility " (Principles and possibilities for optical parameteric chirped pulse amplifies) literary composition, but the device of the higher practicality of a kind of enlargement ratio is not provided.

Summary of the invention:

The purpose of this invention is to provide a kind of optical parametric amplifier that the light intensity of weak laser signal light can be amplified.And using of the present invention simple in structurely, maneuverable amplifying device will obtain the flashlight of desired amplification light intensity.

Optical parametric amplifier of the present invention as shown in Figure 1, comprises that most crucial element is an amplifier element 4, places the plane of incidence r of amplifier element 4 before signal optical source 1 and pump light source 2 to be arranged, and signal optical source 1 and pump light source 2 are connected with same isochronous controller 3.Place the exit facet C of amplifier element 4 to have the output of first detector 5 and second detector, 6, the first detectors 5 and second detector 6 to be connected to simultaneously on the data processing display 7 afterwards.

Said signal optical source 1 and pump light source 2 are both and constitute with laser.The pump light G of pump light source 2 emissions _pWavelength X _pFlashlight G less than signal optical source 1 emission _sWavelength X _s, i.e. λ _p＜λ _sAnd pump light G _pLight intensity I _pMust be greater than flashlight G _sLight intensity I _s, i.e. I _p＞I _s

Pump light G _pWith flashlight G _sBy isochronous controller 3 controls, must enter into simultaneously in the amplifier element 4.Flashlight G _sOptical axis O ₁O ₁Perpendicular to the plane of incidence r of amplifier element 4, and pump light G _pOptical axis O ₂O ₂With flashlight G _sOptical axis O ₁O ₁Between have and be not equal to 0 angle α, i.e. α ≠ 0.

Said amplifier element 4 is made of nonlinear crystal.Nonlinear crystal is a biaxial crystal, potassium titanyl oxygenic phosphate(KTP) crystal (KTP), or lithium triborate crystal in this way (LBO); Or uniaxial negative crystal, PDP crystal (KDP), or ammonium dihydrogen phosphate crystal in this way (ADP), or lithium columbate crystal (LiNO ₃), or beta-barium metaborate crystal (BBO) etc.; Or positive uniaxial crystal, cadmium germanium arsenic crystal (CdGeAs in this way ₂) etc.

In the amplifying device of the present invention, require to incide the flashlight G in the amplifier element 4 _sThe direction of propagation and constitute phase matching angle θ ≠ 0 between the optical axis of crystal direction of amplifier element 4.

The laser of said formation signal optical source 1 and pump light source 2 is solid state lasers, or gas laser, or liquid laser.

Said first detector 5 and second detector 6 all are CCD diode array detectors, or photodiode, or photomultiplier.

Said data processing display 7 is oscilloscopes, or computer, or operative installations.Said isochronous controller 3 is made of delayer.

The course of work of amplifying device of the present invention is: as the two-beam flashlight G that is launched by the signal optical source 1 and the pump light source 2 of isochronous controller 3 controls _sWith pump light G _pIncide simultaneously in the amplifier element 4,, make flashlight G owing to constitute the coupling effect of the nonlinear crystal of amplifier element 4 _sAmplify, by the two-beam of amplifier element 4 outputs, a branch of flashlight G that only is exaggerated _s', another Shu Guang is called idle light G _i

Flashlight G _sGain amplifier in amplifier element 4 is: $G=1+{\left(\mathrm{\&gamma;L}\right)}^2{\left(\frac{\sinh B}{B}\right)}^2---\left(1\right)$ Wherein $B=\sqrt{{\left(\mathrm{\&gamma;L}\right)}^2-{(\mathrm{\&Delta;kL}/2)}^2}$ L is the crystal amplification length as amplifier element 4, and Δ k is the phase misalignment harmonic quantity.Wherein amplification coefficient γ is: $\mathrm{\&gamma;}={4\mathrm{\&pi;d}}_{\mathrm{eff}}\sqrt{I_p/{2\mathrm{\&epsiv;}}_0{n}_p{n}_s{n}_i{\mathrm{c\&lambda;}}_s{\mathrm{\&lambda;}}_i}---\left(2\right)$ (2) d in the formula _EffAs the crystal effective nonlinear coefficient of amplifier element 4, I _pBe pump light G _pIntensity, ε ₀Be permittivity of vacuum, n _pBe pump light G _pRefractive index, n _sBe flashlight G _sRefractive index, n _iBe idle light G _iRefractive index, c is the light velocity, λ _sBe flashlight G _sWavelength, λ _iBe idle light G _iWavelength.

When light is propagated in the crystal as amplifier element 4, when forming different direction propagation with optical axis different refractive indexes is arranged, the relation of phase matching angle and refractive index physical quantity is as follows $\mathrm{tg\&alpha;}=\frac{1}{2}\frac{n_p^2-n_s^2}{({\mathrm{<figure-callout\; id="2"\; label="n\; s"\; filenames="C9912419800061.png,C9912419800071.png"\; state="\{\{state\}\}">n</figure-callout>}}_s^{}{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="C9912419800061.png,C9912419800071.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&theta;}+{\mathrm{<figure-callout\; id="2"\; label="n\; p"\; filenames="C9912419800061.png,C9912419800071.png"\; state="\{\{state\}\}">n</figure-callout>}}_p^{}{\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="C9912419800061.png,C9912419800071.png"\; state="\{\{state\}\}">cos</figure-callout>}}^2\mathrm{\&theta;})}\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="C9912419800061.png,C9912419800071.png"\; state="\{\{state\}\}">sin</figure-callout>}2\mathrm{\&theta;}---\left(3\right)$ In the formula, α is flashlight G _sOptical axis O ₁O ₁With pump light G _pOptical axis O ₂O ₂Between angle, θ is the phase matching angle of the light beam direction of propagation and optical axis of crystal in crystal.

By above-mentioned structure and (1), (2), (3) formula as can be seen the structure of amplifying device of the present invention be not only simply but also reasonable.

The advantage of optical parametric amplifier of the present invention:

1. use amplifying device of the present invention can realize weak signal light G _sLight intensity amplify.And enlargement ratio is above 1,000 times.

2. at the outside flashlight G that adjusts of the crystal of amplifier element 4 _sWith pump light G _pTwo optical axis O ₁O ₁With O ₂O ₂Between angle α operate easily, and whole amplifying device is simple in structure, and is easy to operate.

3. the suitable kind of amplifier element 4 (nonlinear crystal) is more, aforesaid BBO, KDP, LBO, crystal such as KTP.

4. be applicable to broad wavestrip weak signal light G _sAmplification, that is to say the applied widely of signal optical source 1.

5. can select for use the kind of the laser that constitutes signal optical source 1 and pump light source 2 many, as solid state laser, liquid laser, gas laser etc.

Description of drawings:

Fig. 1 is the schematic diagram of optical parametric amplifier of the present invention.

Fig. 2 be embodiment in optical parametric amplifier of the present invention, when amplifier element 4 is uniaxial negative crystal KDP, two-beam G _p, G _sWhen inciding amplifier element 4 plane of incidence γ, the same O of two-beam axle ₁O ₁With O ₂O ₂Between angle α and the graph of relation of the gain G of amplifier element 4.

Embodiment:

Device as shown in Figure 1, signal optical source 1 are the ti sapphire laser output wavelength λ with argon (Ar) ion gas laser pumping solid _sThe flashlight G of=800nm～1.16 μ m _sPump light G _pBe that yttrium-aluminium-garnet (YAG) solid state laser is through frequency multiplication output wavelength λ _p=532nm, two pulse delay units of isochronous controller 3 usefulness constitute adjustment flashlight G _sWith pump light G _pSynchronously, pump light G _pLight intensity I _p=380MW/cm ², amplifier element 4 is negative single shaft KDP nonlinear crystal (length L=13mm), flashlight G _sWavelength X _s=1.06 μ m, flashlight G _sWith pump light G _pTwo optical axis O ₁O ₁With O ₂O ₂Angle α=0.0034rad, curve 1 as shown in Figure 2.θ=37 °, flashlight G _sENERGY E _s=200pJ, the spot diameter that arrives the nonlinear crystal of amplifier element 4 is 1mm, pulsewidth 200ps, amplification coefficient γ=3.297 * 10 ², gain G=1.32 * 10 ³, amplifying signal light G _s' energy $E_s^{*}=264\mathrm{nJ}.$ Obviously the flashlight G that is exaggerated _s' be original flashlight G _sMore than 1,000 times.The a value that shows among Fig. 2 is angle α value, is respectively α=a=0.0034rad, α=a=0.00618rad, α=a=0.018rad, α=a=0.034rad, α=a=0.0618rad, α=a=0.18rad, they are corresponding curve 1,2,3,4,5,6 respectively.As seen from Figure 2, different angle α obtain the gain G difference, and the gain that curve 1 obtains is preferably the highest, as above-mentioned, and the amplifying signal light G that obtains _s' ENERGY E _s ^*Also maximum.

Claims (5)

1. an optical parametric amplifier comprises

＜1〉plane of incidence (r) in amplifier element (4) is equipped with both before and is connected to signal optical source (1) and pump light source (2) on the same isochronous controller (3) simultaneously, exit facet (c) in amplifier element (4) is equipped with both afterwards and is connected to first detector (5) and second detector (6) on the data processing display (7) simultaneously

It is characterized in that:

＜2〉place amplifier element (4) plane of incidence (r) signal optical source (1) and pump light source (2) before to be both with laser and to constitute the pump light (G of pump light source (2) emission _p) wavelength X _pFlashlight (G less than signal optical source (1) emission _s) wavelength X _s, i.e. λ _p＜λ _s, and pump light (G _p) light intensity I _pGreater than flashlight (G _s) light intensity I _s, i.e. I _p＞I _s

＜3〉with pump light G _pIncide the flashlight G in the amplifier element (4) simultaneously _sOptical axis O ₁O ₁Perpendicular to the plane of incidence (r) of amplifier element (4), pump light (G _p) optical axis (O ₂O ₂) and flashlight (G _s) optical axis (O ₁O ₁) between angle 0＜a＜pi/2 is arranged;

＜4〉amplifier element (4) is made of nonlinear crystal, between the direction of propagation of inciding the flashlight (Gs) in the amplifier element (4) and the optical axis of crystal direction of formation amplifier element (4) phase matching angle θ ≠ 0 is arranged.

2. optical parametric amplifier according to claim 1 is characterized in that the nonlinear crystal of said formation amplifier element (4) is a biaxial crystal, potassium titanyl oxygenic phosphate(KTP) crystal (KTP), or lithium triborate crystal in this way (LBO); Or uniaxial negative crystal, PDP crystal (KDP), or ammonium dihydrogen phosphate crystal in this way (ADP); Or beta-barium metaborate crystal (BBO); Or positive uniaxial crystal, as cadmium germanium arsenic crystal (CdGeAs ₂).

3. optical parametric amplifier according to claim 1 is characterized in that the laser of said formation signal optical source (1) and pump light source (2) is a solid state laser, or gas laser, or liquid laser.

4. optical parametric amplifier according to claim 1 is characterized in that said first detector (5) and second detector (6) are CCD diode array detectors, or photodiode, or photomultiplier.

5. optical parametric amplifier according to claim 1 is characterized in that said data processing display (7) is an oscilloscope, or computer, or operative installations.

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