WO2006062073A1 - テラヘルツ波発生方法及び装置 - Google Patents
テラヘルツ波発生方法及び装置 Download PDFInfo
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- WO2006062073A1 WO2006062073A1 PCT/JP2005/022328 JP2005022328W WO2006062073A1 WO 2006062073 A1 WO2006062073 A1 WO 2006062073A1 JP 2005022328 W JP2005022328 W JP 2005022328W WO 2006062073 A1 WO2006062073 A1 WO 2006062073A1
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- terahertz wave
- nonlinear optical
- light
- optical crystal
- pump light
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- 238000000034 method Methods 0.000 title claims abstract description 20
- 239000013078 crystal Substances 0.000 claims abstract description 101
- 230000003287 optical effect Effects 0.000 claims abstract description 83
- 230000000694 effects Effects 0.000 claims description 12
- 230000001174 ascending effect Effects 0.000 claims description 6
- 238000010586 diagram Methods 0.000 description 20
- 238000000605 extraction Methods 0.000 description 13
- 238000002834 transmittance Methods 0.000 description 11
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- 238000001069 Raman spectroscopy Methods 0.000 description 4
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/39—Non-linear optics for parametric generation or amplification of light, infrared or ultraviolet waves
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/3501—Constructional details or arrangements of non-linear optical devices, e.g. shape of non-linear crystals
- G02F1/3509—Shape, e.g. shape of end face
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/35—Non-linear optics
- G02F1/353—Frequency conversion, i.e. wherein a light beam is generated with frequency components different from those of the incident light beams
- G02F1/3534—Three-wave interaction, e.g. sum-difference frequency generation
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2203/00—Function characteristic
- G02F2203/02—Function characteristic reflective
- G02F2203/023—Function characteristic reflective total internal reflection
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2203/00—Function characteristic
- G02F2203/13—Function characteristic involving THZ radiation
Definitions
- the present invention relates to a non-collinear type terahertz wave generation method and apparatus, and more specifically,
- the present invention relates to a method and an apparatus for extracting terahertz waves generated inside a crystal out of the crystal. Explanation of related technology
- Terahertz waves An electromagnetic wave having a frequency around ITHz, that is, far-infrared rays and submillimeter waves in this region are called "terahertz waves”. Terahertz waves are located at the boundary between light waves and radio waves and have characteristics of both light waves and radio waves.
- terahertz waves are the shortest wavelength region that has radio wave material permeability and the longest wavelength that has the straightness of light waves. In other words, it can transmit various substances like radio waves and has a short wavelength (around lmm to around 30 xm), so the highest spatial resolution can be obtained in the radio band, and lenses and It can be routed with a mirror.
- FIG. 1A is a diagram showing the principle of generation of this terahertz wave.
- 1 is a nonlinear optical crystal (for example, LiNbO)
- 2 is pump light (or called excitation light)
- 3 is idler light
- 4 is optical fiber.
- Pump light 2 and idler light 3 are infrared light having a wavelength of about 1 ⁇ m.
- stimulated Raman effect or parametric Due to the interaction, idler light 3 and terahertz wave 4 are generated via the elementary excitation wave (polariton) of the substance.
- the energy expressed by the equation (1) is present between the pump light 2 ( ⁇ ), the terahertz wave 4 ( ⁇ ), and the idler light 3 ( ⁇ ).
- Equation (2) is a vector, and the non-collinear phase matching condition can be expressed as shown in Fig. 1B.
- the idler light 3 and the terahertz wave 4 generated at this time have a spatial spread, Depending on the angle of incidence, their wavelengths change continuously.
- TPG THz-wave Parametric Generation
- the basic optical parametric process is defined by the disappearance of one pump photon and the simultaneous production of one idler one photon and one signal photon.
- parametric oscillation occurs when the pump light intensity exceeds a certain threshold or value.
- the disappearance of one pump photon and the simultaneous production of one idler photon and one polariton are stimulated Raman scattering, which is included in the broad parametric interaction.
- the terahertz wave generated by the above-described terahertz wave generation device having a single-repath arrangement is very weak, and most of the force is absorbed while traveling through the nonlinear optical crystal by several hundred ⁇ . There was a problem of being. For example, due to absorption of LiNbO crystals, the length 3
- the terahertz wave While traveling through mm, the terahertz wave has a small value of about 0.1%.
- Patent Documents 1 and 2 are disclosed.
- Patent Document 3 unpublished
- Non-Patent Documents 1 and 2 are related to the present invention.
- FIG. 2 is a schematic diagram of a submillimeter wave generator disclosed in Patent Document 1.
- the intensity of the idler light 3 in the specific direction can be increased.
- 5 is a laser device that irradiates laser light as pump light 2
- 6 is a prism for taking out the terahertz wave 4 to the outside.
- the prism 6 is made of a material having a small absorption coefficient with respect to the terahertz wave.
- FIG. 3 is a schematic diagram of a terahertz wave generating device disclosed in Patent Document 2.
- the first laser beam 7 having a single frequency is used as the pump beam 2 and another second laser beam 8 having a single frequency is injected in the direction of generation of the idler beam 3.
- the generated terahertz wave output can be greatly increased.
- reference numeral 9 denotes a prism array in which a plurality of the prisms 6 described above are arranged.
- Patent Document 1 Japanese Patent Laid-Open No. 09-146131, “Submillimeter Wave Generator”
- Patent Document 2 Japanese Patent Application Laid-Open No. 2002-072269, “Terahertz Wave Generation Method and Apparatus”
- Patent Document 3 Japanese Patent Application No. 2003-107885, unpublished
- Non-patent literature 1 K. Kawase et. Al, Arrayed silicon prism coupler for a THz— wave parametric oscillator, Applied Optics, vol. 40, No. 9, pp. 1423-1426, 2001
- Non-Patent Document 2 K. Kawase et. Al, Tsuji , erahertz wave parametric source ", Journal of Physics D; Applied Physics, vol. 35, No. 3, pp. R1-R14, 2 002
- pump light is applied to the nonlinear optical crystal 1 having Raman activity and far-infrared activity.
- idler light 3 and terahertz wave 4 are generated due to nometric interaction.
- the idler light 3 and the terahertz wave 4 generated at this time have a spatial spread in the direction satisfying the phase matching condition shown in FIG. 1, and their wavelengths change continuously according to the emission angle. .
- the intensity of the idler light 3 and the terahertz wave 4 in the specific direction can be increased.
- the generation point of the terahertz wave is inside the nonlinear optical crystal, the absorption capacity inside the crystal is large.
- the LiNbO crystal absorbs and advances 3mm in length.
- terahertz waves decrease to about 0.1%.
- the present invention has been devised in order to solve an enormous problem. That is, the object of the present invention is to provide a terahertz wave close to rotational symmetry that can greatly reduce absorption in the crystal, increase the extraction efficiency from the interface to the outside, and can be easily applied to a Gaussian optical system. It is an object of the present invention to provide a terahertz wave generation method and apparatus capable of obtaining a high output distribution. Summary of invention
- pump light is incident on a nonlinear optical crystal capable of generating a terahertz wave by a parametric effect, and idler light and a terahertz wave are generated in a direction satisfying a non-collinear phase matching condition.
- a terahertz wave generation method
- One end face of the nonlinear optical crystal is made almost orthogonal to the direction in which the terahertz wave is generated, the pump light and idler light are totally reflected at substantially the same point on the end face, and the generated terahertz wave is emitted almost vertically.
- a method for generating a terahertz wave is provided.
- a nonlinear optical crystal capable of generating a terahertz wave by a parametric effect, and a laser device for injecting pump light into the nonlinear optical crystal, and satisfying a noncollinear phase matching condition.
- a terahertz wave generator that generates idler light and terahertz waves in the direction,
- One end face of the nonlinear optical crystal is almost perpendicular to the direction of generation of the terahertz wave, and the pump light and idler light are totally reflected at substantially the same point on the end face, and the generated terahertz wave is emitted almost vertically.
- a terahertz wave generator characterized in that the terahertz wave is positioned as described above.
- the terahertz wave is generated by totally reflecting the pump light and idler light at substantially the same point on one end face of the nonlinear optical crystal.
- the location becomes the end face of the crystal or near the end face, so that absorption in the crystal can be greatly reduced.
- the generated terahertz wave is emitted almost perpendicularly to the one end face of the nonlinear optical crystal, it is possible to increase the extraction efficiency from the interface where there is almost no reflection at the end face (interface).
- the generation point of the terahertz wave is at or near the total reflection point of the pump light and idler light, and is substantially generated at one point and emitted almost perpendicular to the end face.
- Terahertz wave output distribution close to rotational symmetry can be obtained easily
- incident angles ⁇ ⁇ and ⁇ i of the bump light and idler light with respect to the end face of the nonlinear optical crystal are incident angles of terahertz waves larger than the respective total reflection angles. Is smaller than the total reflection angle.
- the pump light and idler light can be totally reflected at the end face of the nonlinear optical crystal, and the terahertz wave can be extracted outside without total reflection.
- a first laser device that outputs a first laser beam as the pump light
- an ascending type resonator that totally reflects and amplifies idler light generated in the nonlinear optical crystal at the total reflection point.
- an ascending type resonator that makes the first laser light incident as the pump light, totally reflects and amplifies idler light generated in the nonlinear optical crystal at the total reflection point.
- the resonator preferably amplifies the idler light by making multiple round trips.
- the first laser light can be incident as the pump light, and the idler light generated in the nonlinear optical crystal can be totally reflected and amplified at the total reflection point.
- the crest-type resonator is placed on a rotating stage and rotated, and the wavelength of the terahertz wave can be continuously changed by changing the angle of the pump light with respect to the resonator.
- the angle of the pump light to the resonator can be changed with respect to the fixed resonator by changing the incident angle of the pump light with a movable mirror or the like. It can also be changed.
- a first laser device that outputs a first laser beam having a single frequency as the pump light, and another second signal having a single frequency in a generation direction of idler light generated in the nonlinear optical crystal.
- a second laser device for injecting laser light, and the pump light is simply A first laser beam with a single frequency is used, and another idler laser beam with a single frequency is injected in the direction of the idler generated within the nonlinear optical crystal.
- the second laser device is used to inject another second laser beam having a single frequency in the direction of generation of idler light generated in the nonlinear optical crystal, idler waves are generated in the nonlinear optical crystal only by parametric interaction. It is possible to generate a stronger idler wave than to generate. As a result, the light intensity of the idler wave in this direction is increased, and the intensity of the terahertz wave that satisfies the non-collinear phase matching condition can be greatly increased.
- the direction of the generated terahertz wave is high because the directivity of the idler wave enhanced by the second laser beam is strong and both the first and second laser beams are single-frequency laser beams. If the directivity of the signal increases, the spectrum width that is swept by force can be significantly narrowed.
- the wavelength of the terahertz wave can be changed.
- the first laser device is a variable wavelength laser device capable of changing a wavelength of pump light.
- the wavelength of the terahertz wave can be changed by changing the wavelength of the pump light.
- a reflection reducing member that reduces the reflectance of the terahertz wave is provided on one end face of the nonlinear optical crystal.
- the refractive index is gradually brought closer to the refractive index of the atmosphere, thereby reducing the reflectance and reducing
- the extraction efficiency of the rutz wave can be improved.
- the reflection of the terahertz wave at the end face can be further reduced, and the extraction efficiency from the interface to the outside can be further increased.
- a condensing lens for condensing the terahertz wave is provided on one end surface of the nonlinear optical crystal. Is preferable.
- a powerful condensing lens can extract terahertz waves as parallel light.
- the terahertz wave can be focused on the end face of the terahertz fiber and can be freely propagated through the terahertz fiber.
- the number of optical elements can be reduced and an efficient optical system can be arranged.
- the terahertz wave generation method and apparatus of the present invention can significantly reduce absorption in the crystal, increase the extraction efficiency from the interface to the outside, and improve the Gaussian optical system. It has excellent effects such as the ability to obtain a terahertz wave output distribution that is easy to apply and close to rotational symmetry.
- FIG. 1 A and B are diagrams showing the generation principle of terahertz waves.
- FIG. 2 is a schematic diagram of a submillimeter wave generator disclosed in Patent Document 1.
- FIG. 3 is a schematic diagram of a terahertz wave generator disclosed in Patent Document 2.
- FIG. 4 is a first embodiment of the terahertz wave generator according to the present invention.
- FIG. 5 is an explanatory diagram of an incident angle and a refractive index with respect to a terahertz extraction surface of pump light and idler light in the present invention.
- FIG. 6 is a diagram showing a second embodiment of the terahertz wave generator according to the present invention.
- FIG. 7 is a diagram showing the relationship between the incident angle of the terahertz wave and the transmittance in the present invention.
- FIG. 8 is a diagram showing a third embodiment of the terahertz wave generator according to the present invention.
- FIG. 9 is a diagram showing a fourth embodiment of the terahertz wave generator according to the present invention.
- FIG. 10 is a configuration diagram of an experimental optical system of the terahertz wave generation device of the present invention.
- FIG. 11 is a diagram showing a beam shape of a terahertz wave generated in the present invention.
- FIG. 12 is an input / output characteristic diagram of a terahertz wave generated in the present invention.
- FIG. 4A is a diagram showing a first embodiment of the terahertz wave generation device of the present invention.
- the terahertz wave generator 10 of the present invention includes a nonlinear optical crystal 12 capable of generating terahertz waves by a norametric effect, and pump light 2 in the nonlinear optical crystal 12.
- the terahertz wave generator 10 further includes a peak-type resonance that totally reflects and amplifies the idler light 3 generated in the nonlinear optical crystal 12 at the same total reflection point 13. 15 with a vessel.
- the resonator 15 includes two reflecting mirrors 15a and 15b. The reflection mirrors 15a and 15b are configured to amplify the idler light 3 generated in the nonlinear optical crystal 12 by transmitting the pump light 2 and reflecting the idler light 3.
- a second laser device that injects another second laser beam having a single frequency in the generation direction of the idler light 3 generated in the nonlinear optical crystal 12 may be provided.
- the first laser device 14 is preferably a variable wavelength laser device that can change the wavelength of the pump light 2. Also, instead of using a tunable laser device, the incident angle of the pump light can be changed without changing the other components.
- FIG. 4B shows the angle phase matching condition at the total reflection point 13.
- one end face 12a (the upper face in this figure) of the nonlinear optical crystal 12 is substantially orthogonal to the direction in which the terahertz wave 4 is generated.
- the idler light 3 is totally reflected, and the terahertz wave 4 generated thereby is positioned so as to be projected almost vertically.
- FIG. 5 is an explanatory diagram of the incident angle and refractive index of the pump light and idler light with respect to the terahertz extraction surface in the present invention.
- the incident angles ⁇ ⁇ and ⁇ i of the pump light 2 and the idler light 3 with respect to the end face 12a of the nonlinear optical crystal 12 are set larger than the respective total reflection angles ⁇ r.
- the incident angle of the terahertz wave 4 with respect to the end face 12a is set to be substantially orthogonal to the end face 12a in this example, which is smaller than the total reflection angle.
- FIG. 4A when pump light 2 (excitation light) is incident on nonlinear optical crystal 12, idler light 3 and terahertz wave 4 are generated by a non-collinear parametric effect via polaritons.
- the idler wave 3 and the terahertz wave 4 generated at this time have a spatial extent, and their wavelengths change continuously according to the emission angle.
- the resonator 15 By configuring the resonator 15 in a specific direction (angle ⁇ i) with respect to the idler light 3 emitted with a spatial spread, the intensity of the idler light 3 in the specific direction can be increased.
- the phase matching condition which is the energy conservation law and the momentum conservation law shown in Eqs. (1) and (2), is established between the pump light 2 (excitation light), idler light 3, and terahertz wave 4.
- the invention injects pump light 2 (excitation light) obliquely into the end face 12a of the nonlinear optical crystal 12, totally reflects it at the end face 12a of the nonlinear optical crystal 12, and rises left and right symmetrically with the total reflection point 13 as the apex.
- the terahertz wave 4 is extracted substantially perpendicularly to the end face 12a of the nonlinear optical crystal 12.
- the reflectivity at the end face 12a can be suppressed, the extraction efficiency of the terahertz wave 4 can be improved, and the emitted terahertz wave can be improved.
- Four beam shapes can be extracted with a Gaussian beam profile. Furthermore, by making the extraction surface of the terahertz wave 4 the total reflection point 13 of the idler light 3, absorption loss of the terahertz wave 4 due to the nonlinear optical crystal 12 can be avoided, and the emission efficiency is improved.
- the light 3 forms, for example, 64.3 ° and 65 ° with the terahertz wave 4 respectively. Therefore, in order to generate the terahertz wave 4 perpendicularly to the crystal end surface 12a (exit angle 0 °), the crystal end surface It is necessary to make the pump light incident at 64.3 °. At this time, it is necessary to arrange the two mirrors 15a and 15b so that the idler light is generated at an angle of 65 ° with respect to the end face. In FIG. 5, if the wavelength of pump light 2 is 1.064 zm, the wavelength of idler light 3 is 1.07 ⁇ m, and the refractive index n of LiNbO for these wavelengths is 2.15. Whole fabric
- the angle of incidence ⁇ r is 27.7 °. Therefore, by setting the incident angles ⁇ ⁇ and ⁇ i of the pump light 2 and idler light 3 to 64.3 ° and 65 °, the pump light 2 and idler light 3 incident on the crystal end face 12a are totally reflected and peaked.
- the resonator 15 can be configured.
- FIG. 6 is a second embodiment of the terahertz wave generator according to the present invention.
- a reflection reducing member 16 that reduces the reflectivity of the terahertz wave 4 is provided on one end face 12 a of the nonlinear optical crystal 12.
- the reflection reducing member 16 is designed and selected to reduce the refractive index and / or thickness of the terahertz wave 4 at the crystal end face 12a, and more preferably to the terahertz.
- the transmittance T at the interface (end face 12a) also depends on the refractive index difference.
- a low refractive index material 16 is attached to the end face 12a of the nonlinear optical crystal 12 to suppress internal reflection and improve the extraction efficiency into the atmosphere. be able to.
- the light transmittance depends on the incident angle at the boundary surfaces having different refractive indexes.
- the refractive index n of the terahertz wave band is
- FIG. 7 is a relationship diagram between the incident angle of the terahertz wave and the transmittance in the present invention.
- the horizontal axis is the incident angle
- the vertical axis is the transmittance, which is the result of calculating the transmittance of the terahertz wave that appears in the atmosphere.
- ⁇ sel indicates that LiNbO crystal is used as the nonlinear optical crystal
- the incident angle is 0 °, that is, when emitting vertically from the nonlinear optical crystal. Yes. That is, it can be seen that when the terahertz wave 4 is extracted vertically from the nonlinear optical crystal 12, the terahertz wave can be extracted most efficiently.
- Case 2 and case 3 in FIG. 6 show the case where a low refractive index substrate is attached as the reflection reducing member 16.
- Case2 has a MgO (refractive index 3.25) low refractive index substrate on the end face of LiNbO.
- case3 When attached, case3 has a low refractive index substrate 16 and terahertz wave on the end face of LiNbO.
- the condition for this low refractive index is that the pump light and idler light are totally reflected at the end face with the nonlinear optical crystal.
- LiNb ⁇ crystal is used as the nonlinear optical crystal and MgO crystal is used as the reflection reducing member
- the refractive index of LiNbO and MgO is 2 ⁇ 15, 1.72, respectively.
- the angle of incidence is 53.1 ° at the boundary.
- the incident angles of the pump light and idler light on the crystal are 64.3 ° and 65 °, so the pump light and idler light are 64.3 ° and 65 Incident at °. Since this is a total reflection angle greater than 53.1 °, total reflection occurs, and an ascending resonator configuration is possible.
- the beam shape of the terahertz wave can be extracted with a nearly Gaussian beam profile without any disturbance.
- the silicon prism array 9 was used to extract the terahertz wave, so the wavefront was disturbed, and it was necessary to use multiple lenses for light collection.
- a terahertz wave is emitted from a plane, a Gaussian beam diameter is emitted, so these problems can be improved.
- FIG. 8 and FIG. 9 are third and fourth embodiments of the terahertz wave generator according to the present invention.
- a condensing lens 18 that condenses the terahertz wave 4 in addition to the low refractive index substrate 16 is directly attached to one end face 12a of the nonlinear optical crystal 12.
- a collimating lens made of the reflection reducing member described above may be directly attached.
- a fiber coupler in which the lens 18 and the terahertz fiber 19 are combined can be directly attached as shown in FIG.
- FIG. 10 is a configuration diagram of an experimental optical system of the terahertz wave generator according to the present invention.
- the nonlinear optical crystal 12 is composed of two 4 ⁇ 5 ⁇ 50 mm LiNbO crystals and a trapezoid.
- the top surface 12a of the nonlinear optical crystal 12 has a thickness
- An lmm MgO substrate 16 is pasted, and the terahertz wave 4 is taken out from it.
- a 1.064 zm Nd: YAG laser 14 was used.
- the pump light 2 enters the resonator from the mirror (Ml) 15a, is reflected by the ascending apex (top end surface 12a), and exits from the mirror (M2) 15b.
- the idler light 3 generated in the crystal is resonated and amplified by the resonator mirrors Ml and M2, and the terahertz wave 4 is emitted in the vertical direction from the peak 12a.
- the emitted terahertz wave 4 is detected by the porometer detector 23 through the MgO substrate 16 and the terahertz lens 22.
- Reference numeral 21 denotes a damper that blocks the pump light 2.
- FIG. 11 is a diagram showing the beam shape of the terahertz wave generated in this example.
- This figure shows the transverse beam shape measured approximately 20 cm from the MgO substrate 16. The measurement was performed by scanning a lmm ⁇ pinhole on the stage and plotting the intensity. From this figure, it was confirmed that the full width at half maximum was about 7 mm, and the light was emitted in a Gaussian shape.
- the terahertz wave at this time is 1.6 THz.
- FIG. 12 is an input / output characteristic diagram of the terahertz wave generated in the present invention.
- the oscillation threshold was 13.5 mjZpulse.
- the output of the terahertz wave was 42pj / pulse with respect to the pump light input of 26mjZpulse, and an output almost equivalent to that of the conventional terahertz wave parametric oscillator was observed. This is almost five times the saturation energy of the porometer detector, and is sufficient output energy for various spectroscopic measurements.
- the generation point of the terahertz wave is at or near the total reflection point of the pump light and idler light, and is substantially generated at one point and emitted almost perpendicularly to the end face. It was also confirmed from the example in Fig. 11 that a terahertz wave output distribution close to rotational symmetry that can be easily applied to the Gaussian optical system can be obtained.
- the present invention it is possible to reduce the loss due to reflection, avoid the disturbance of the wavefront, and improve the beam shape by extracting the terahertz wave perpendicularly from the crystal end face.
- this configuration it is possible to attach an AR coating, a terahertz wave fiber, or the like, which has been difficult until now, in an integrated manner with the light source as shown in the embodiment.
- the pump light and idler light are reflected by the end face of the nonlinear optical crystal, and the ascending type resonator having the reflection point as the apex is formed.
- the reflection angle at the end face of the pump light is an angle at which the pump light itself and the idler light are totally reflected and the terahertz wave is emitted perpendicularly to the reflection face under the phase matching condition.
- pump light and idler light are totally reflected at the terahertz wave emission point (reflecting point of pump light and idler light), and a material that reduces the reflection of terahertz wave is used. It is important to install.
- MgO crystal has a refractive index of 1.72 for pump light and idler light and a refractive index of 3.25 for terahertz waves, which reduces the reflection of terahertz waves on the nonlinear optical crystal plane. It becomes possible to configure a resonator for idler light.
- a lens 18 or resin can be attached to the MgO substrate 16. Note that the present invention is not limited to the above-described examples and embodiments, and various changes can be made without departing from the spirit of the present invention.
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Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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DE602005014378T DE602005014378D1 (de) | 2004-12-08 | 2005-12-06 | Verfahren und einrichtung zum erzeugen einer terahertzwelle |
EP05814662A EP1821141B1 (en) | 2004-12-08 | 2005-12-06 | Method and device for generating terahertz wave |
US11/721,278 US7710637B2 (en) | 2004-12-08 | 2005-12-06 | Method and apparatus for generating terahertz wave |
Applications Claiming Priority (2)
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JP2004-355182 | 2004-12-08 | ||
JP2004355182A JP4609993B2 (ja) | 2004-12-08 | 2004-12-08 | テラヘルツ波発生方法及び装置 |
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EP (1) | EP1821141B1 (ja) |
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US8514482B2 (en) | 2009-04-16 | 2013-08-20 | Nalux Co., Ltd. | Terahertz electromagnetic wave generating element |
CN103097952A (zh) * | 2010-08-24 | 2013-05-08 | 佳能株式会社 | 电磁THz波产生器件、电磁THz波检测器件和时域分光装置 |
US9244331B2 (en) | 2010-08-24 | 2016-01-26 | Canon Kabushiki Kaisha | Electromagnetic wave generating device, electromagnetic wave detecting device, and time-domain spectroscopy apparatus |
CN114545585A (zh) * | 2022-02-23 | 2022-05-27 | 华太极光光电技术有限公司 | 一种确定抛物面镜与硅棱镜之间的位置的方法 |
CN114545585B (zh) * | 2022-02-23 | 2024-04-26 | 华太极光光电技术有限公司 | 一种确定抛物面镜与硅棱镜之间的位置的方法 |
Also Published As
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EP1821141A1 (en) | 2007-08-22 |
US7710637B2 (en) | 2010-05-04 |
JP4609993B2 (ja) | 2011-01-12 |
DE602005014378D1 (de) | 2009-06-18 |
EP1821141B1 (en) | 2009-05-06 |
JP2006163026A (ja) | 2006-06-22 |
EP1821141A4 (en) | 2008-06-25 |
US20090251767A1 (en) | 2009-10-08 |
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