CN1136719A - Input-only sealed ring type optical cavity and its use - Google Patents
Input-only sealed ring type optical cavity and its use Download PDFInfo
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- CN1136719A CN1136719A CN 95105306 CN95105306A CN1136719A CN 1136719 A CN1136719 A CN 1136719A CN 95105306 CN95105306 CN 95105306 CN 95105306 A CN95105306 A CN 95105306A CN 1136719 A CN1136719 A CN 1136719A
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Abstract
The present invention provides a new type passive optical cavity. Its structure is characterized by that it only has input port of luminous energy, and the light path in the cavity is made up in the form of one-way closed ring. Said optical cavity features that it can store light-beam energy, overlap light-beam intensity and make the light-beams coming from different directions change into the equidirectional and common-way propagation, can raise various photoconversion efficiencies such as frequency multiplication, sum-frequency, beat frequency, upper harmonic, parametric conversion, four-wave mixing and continuous-wave pumping laser production, etc.), raise the utilization ratio of luminous energy of high-frequency ligh modulation and reduce the working voltage of the optical switch of the high-frequency light modulation.
Description
The present invention relates to a class optics cavity, and their purposes.
Optics cavity has important effect as a kind of Optical devices in optics science, optical technology.The appearance in novel optical chamber, once to the optics science and technology, and even whole development of modern science and technology played great impetus.As everyone knows, Xiao Luo and Tang Si are at they famous first piece of paper about laser " far infrared and light master " (A.L.Schaw-low and C.H.Townes, Infrared and Optical Masers, Phys.Rev., 112,1940 (1958)) in, just because of the imagination that has proposed the open type optical resonator, thereby the microwave of stimulated radiation is amplified--the operation principle that is Maser can be applied to the optical frequency district, makes the light wave of stimulated radiation amplify to become possible (referring to document: husband's work in the A. Asia, Liu Songhao etc. translate, quantum electronics, Shanghai science tech publishing house, nineteen eighty-three, 183 pages), thus the birth of laser caused.
Now existing polytype optics cavity, have different performances and purposes respectively (referring to document: Yang Chenhua, Mei Suisheng, the Lin Junting chief editor, laser and infrared technique handbook, National Defense Industry Press, nineteen ninety, 260 pages-273 pages), but the optics cavity that does not also have such class passive (being not have active working media in the chamber): after the outer light beam incident of chamber, can be equidirectional with the light beam that in the chamber, moves, with ground, path along the ring-like light path circulating propagation of a sealing, thereby be stored into the irradiating light beam energy, and make that stack strengthens in its continuous circulation in the chamber.Such novel passive optical chamber will obtain important use in optical technology.
The purpose of this invention is to provide this class novel optical chamber, and the purposes aspect driving voltage, driving magnetic field or the driving distribution of light intensity of their working medias in acquisition intense light pulse, the efficient that improves the optical nonlinearity conversion, the efficiency of light energy utilization that improves the high frequency light modulating device and reduction high frequency light modulating device.
The object of the present invention is achieved like this: make such class optics cavity, their structural feature is that light path formation unidirectional blocking is ring-like in the chamber, have only the chamber outer light beam to enter the input port of this ring-like light path, and do not have to make the output port of the light beam outgoing that on this ring-like light path, moves, thereby constitute a class input-only sealed ring type optical cavity.But in the outer light beam incident chamber, chamber, can only in the ring-like light path of a sealing, repetitive cycling move and can not export then, because the lasting remittance of outside energy, chamber inner light beam intensity just constantly strengthens, when the energy loss speed of the input rate and optical cavity self of ambient light energy equates and reach a balance stable state peak.Though the energy loss of optical cavity self is inevitable, its speed can take measures it is reduced as far as possible, thereby makes chamber inner light beam intensity much larger than former incident value.
Input-only sealed ring type optical cavity of the present invention can by a special input mouth mirror and beam-shrinked mirror, reflector group or and an optical fibre ring, convergent lens group formed, also can be formed by a special input port combined lens and an optical fibre ring, wherein the input mouth mirror can be divided into two kinds of reflective and transmission-types again, distinguish according to used input mouth mirror or input port combined lens kind, so can constitute three kinds of input-only sealed ring type optical cavities.The design of input mouth mirror and input port combined lens and manufacturing are the keys that this type of optics cavity is made.
For reflective input mouth mirror, be to adopt optical material to make the sheet base (also can make the sheet base with other material earlier with good reflection rate, after following structure fabrication finishes, plate reflection enhancing coating more thereon), make numerous parallel isoceles triangle grooves in surface thereof, the cross section that is them is an isosceles triangle, and the geometry of each groove is identical.Leg-of-mutton base length is much larger than incident wavelength (generally greater than two to three orders of magnitude of wavelength), and the angle at two base angles is 30 degree.Because two sides of each triangular groove all form a tiny rectangular mirror, the integral body of numerous triangular grooves just constituted a kind of structure special have the speculum of symmetric double to reflection function, thereby the two monochromatic collimated beam bundles of restrainting by two symmetry direction incidents can be reflexed to a specific direction, and along same propagated (seeing back embodiment and explanation for details).If one in two incident beams is input beam outside the chamber, another be in the chamber through the circulation light beam of catadioptric time of beam-shrinked mirror, speculum, the input-only sealed ring type optical cavity that then has reflective input mouth mirror just can be formed.
For transmission-type input mouth mirror, then be adopt optical material to make the sheet base with good transmissivity (and can be after following structure fabrication finishes, plate anti-reflection film to increase transmissivity on its surface again), also make the parallel isoceles triangle groove of numerous base length much larger than incident wavelength in surface thereof, the shape of each groove is identical, but the angle at leg-of-mutton two base angles be according to the sheet base refractive index, can converge to same direction after two bundle incident lights refractions are seen through and obtain the requirement of maximum luminous energy collection efficiency and (the seeing back embodiment and explanation for details) determined as calculated.Obviously, this also makes it become the special refracting telescope with bi-directional symmetrical reflective functions of a kind of structure, it also can be refracted to a same direction with the two monochromatic collimated beam bundles of restrainting by symmetry direction incident, thereby this port mirror just can constitute the input-only sealed ring type optical cavity with transmission-type input mouth mirror with beam-shrinked mirror, when reflector group cooperates.
Described input port combined lens, then be that (convex lens, gradient-index lens etc. are shown referring to document: Qiao Yafu by one group of convergent lens, graded index optics, Science Press, 1992,333 pages) form, two two-port places that place an optical fibre ring respectively wherein, make the divergent beams of the output of optical fibre ring one end thus be converged to directional light, outside optical fiber, propagate certain distance after, assemble by another lens that place this optical fibre ring other end again and re-enter this optical fiber.Other has the transport optical fiber of an optical fiber as the chamber outer light beam, the output of its output and optical fibre ring is pressed close to, so that make the divergent beams that transport optical fiber output thus, by the 3rd convergence that places the convergent lens of its port, or also become collimated light beam after the convergence of the same convergent lens at the output port place by placing optical fibre ring, and import optical fibre ring after the convergence of convergent lens as much as possible through placing the optical fibre ring input.So the beam energy in the optical fibre ring can only circulate in optical fibre ring (constituting ring-like chamber), and the light energy outside the chamber is constantly injected, thereby has just formed the input-only sealed ring type optical cavity with input port combined lens.
Above-mentioned three kinds of input-only sealed ring type optical cavities have following important use: at first, because the light beam of incident outside the chamber, the light intensity stack by circulation in the chamber, pulsewidth shorten, make it place the direction of beam propagation switching device shifter changed course in the chamber and export through one in due course, then can obtain high intensity light pulses; Secondly, this type of optics cavity can be used for improving the efficient of the optical nonlinearity conversion of extensive use in optical technology, frequency multiplication for example, and frequently, difference frequency, high order harmonic component, parameter change, the laser generation of four wave mixing even continuous wave pumping etc., because for these optical transition, because conversion efficiency is less than 1, then just remain in its input light or the pump light light energy part that does not obtain changing is arranged, by sealing ring-like light path, they repeatedly can be imported the conversion work medium again and change again that (light energy that obtains changing is partly by a light-splitting device, can change the direction of propagation and export), the raising that adds light intensity also can strengthen non-linear conversion efficient, thereby can improve total conversion efficiency; In addition, on the chamber inner ring type light path of this type of sealing ring-type optical chamber, placement is by electricity causes, mangneto or photic plane of polarization rotating media and polarized light splitting device are formed high frequency light modulating device, the beam energy of not modulated device output is temporarily stored along the circulation of chamber inner ring type light path, and incident modulating device once more, just can be reused, thereby improve the utilance of high frequency light modulating device incident optical energy; And, the stack because incident beam circulates in the chamber, thereby the light intensity of these light modulation mediums of incident is strengthened significantly, the driving voltage of the former amplitude light intensity of output that this makes, and electricity causes, mangneto or photic plane of polarization rotating media are required, driving magnetic field or drive distribution of light intensity and reduce (seeing back embodiment and explanation for details).
Input-only sealed ring type optical cavity of the present invention is a kind of optics cavity of brand-new type, they have can superimposed light beam intensity, store beam energy and make the light beams (incident beam and chamber in operation bundle) of two bundle different directions, different propagated in the chamber outside become equidirectional, propagate with the path and (to be merged into to move in the new chamber and to restraint, no matter and the polarization properties of two light beams is how, these are different with birefringent back wash effect) function.
Input-only sealed ring type optical cavity provided by the present invention obtain intense light pulse, improve the optical nonlinearity conversion efficient, improve the efficiency of light energy utilization of high frequency light modulating device and reduce working media in the high frequency light modulating device required driving voltage, driving magnetic field or drive application aspect the distribution of light intensity, compared with the prior art, have following advantage and good effect respectively:
One. in the application facet that obtains intense light pulse, advantage compared with the prior art:
The method that obtains intense light pulse in the prior art mainly is to transfer Q and locked mode (referring to document: husband's work in the A. Asia, Liu Songhao etc. translate, quantum electronics, Shanghai science tech publishing house, nineteen eighty-three, 257 pages-291 pages).
Compare with transferring Q, using the major advantage of closed-loop die cavity is to obtain shorter light pulse.For example can with this type of optics cavity further compression through the light pulse of toning Q, the pulsewidth of general accent Q light pulse is that tens nanosecond orders are (referring to document: Yang Chenhua, Mei Suisheng, the Lin Junting chief editor, laser and infrared technique handbook, National Defense Industry Press, nineteen ninety, 344 pages-345 pages), i.e. the length of this kind light pulse in air dielectric is about several meters magnitudes, it is imported ring-like chamber, because the circulation superposition of light beam in the chamber, incident light pulse will become and chamber isometric (general chamber length is tens centimetres), if allow apace subsequently outside its output cavity, then the emergent light pulse length also just has only tens centimetres, thereby pulse duration shortens into nanosecond order.
Compare with locked mode, using the major advantage of closed-loop die cavity is to obtain higher single pulse energy.General locked mode optical pulse width is a picosecond magnitude, peak power be the hundreds of megawatt (referring to document: Yang Chenhua, Mei Suisheng, Lin Junting chief editor, laser and infrared technique handbook, National Defense Industry Press, nineteen ninety, 686 pages), therefore, its every pulse energy is the millijoule magnitude.And above-mentioned will transfer the light pulse of exporting again after the Q light pulse compression and obtaining, even the repeatedly circulation losses in chamber is greatly to 20%, every pulse energy of output also has 80% of input pulse energy, promptly generally also can reach tens to the hundreds of millijoule (referring to document: Yang Chenhua, Mei Suisheng, Lin Junting chief editor, laser and infrared technique handbook, National Defense Industry Press, nineteen ninety, 344 pages-345 pages).
Two. in the application facet that improves the optical nonlinearity conversion efficiency, advantage compared with the prior art:
For the conversion of the nonlinear optics of extensive use in the Modern Optics Technology, wherein Jue Daduoshuo conversion efficiency is less than 1, promptly import light or pump light can not all convert to expect the light beam of character and outgoing.There are some kinds of existing methods can improve one or more conversion efficiency in the above-mentioned multiple optical transition, for example use intracavity frequency doubling, the method of phase matched and increase light intensity improves shg efficiency, improve the efficient that produces high order harmonic component with the method that increases light intensity, improve the efficient of parameter change with the method for parametric oscillation, the efficient etc. that improves four wave mixing with the method for four wave mixing in the chamber is (referring to document: Shen Yuan earth work, the nonlinear optics principle, Science Press, 1987, the first volume and document: husband's work in the A. Asia, Liu Songhao etc. translate, quantum electronics, Shanghai science tech publishing house, nineteen eighty-three, the 10th, 16,17 chapters).With compare with the method for four wave mixing in the chamber with intracavity frequency doubling, using the advantage of closed-loop die cavity is will not place in the laser chamber by transfer medium, thereby does not resemble these two kinds of methods and be severely limited in actual applications; Compare with the method that increases light intensity, the advantage of using the closed-loop die cavity is the requirement reduction to the power level of input beam, makes middle and high power input light also can reach the conversion efficiency of very high power input light; And compare with the method for phase matched, the advantage of using the closed-loop die cavity is to realize the high efficiency conversion easily, because of phase-matching condition is difficult to desirable satisfied in practice.
Three. in the application facet of the efficiency of light energy utilization that improves the high frequency light modulating device, do not see the report of other relevant technologies as yet, belong to a completely new approach that addresses this problem.
Four. in reducing the high frequency light modulating device electricity cause, the application facet of driving voltage, driving magnetic field or the distribution of light intensity of mangneto or photic plane of polarization rotating media, advantage compared with the prior art:
At present, the electricity that uses in the high frequency light modulating device causes the plane of polarization rotating media--and be electrooptic crystal, its occupation mode has vertical utilization and laterally uses two kinds.For vertical utilization, (referring to document: edit in Li Jing town to reduce the required driving voltage of electrooptic crystal and mainly be the method that adopts polylith crystal optics polyphone, electricity and connect, the optics handbook, Shaanxi science tech publishing house, 1986,1087 pages), for example if with four crystal polyphones, then driving voltage is reduced to 1/4th of monolithic crystal, but such voltage drop low amplitude is still felt in actual use too big (generally still near kilovolt), if further increase the crystal block number, then device is too complicated, and the boundary reflection loss also can obviously increase.By comparison, easily driving voltage is reduced to below 1/10th of monolithic crystal behind the use closed-loop die cavity, the increase of device manufacture difficulty and reflection loss also relative less (seeing back embodiment and explanation for details).For horizontal utilization, reduce the required driving voltage of electrooptic crystal and mainly be and adopt the method that increases crystal length, reduce the crystal width (referring to document: edit in Li Jing town, the optics handbook, Shaanxi science tech publishing house, 1986,1080 pages), the driving voltage of this kind electrooptical switching can be reduced to hundreds of even tens volts, but therefore the width of crystal reduces significantly, thereby causes the clear aperature of switch to reduce.By comparison, use the closed-loop die cavity can not reduce the clear aperature (seeing back embodiment and explanation for details) of switch.
Mangneto or the driving magnetic field of photic plane of polarization rotating media or the application facet of distribution of light intensity in reducing the high frequency light modulating device are not seen the report of other relevant technologies as yet.
Accompanying drawing drawing explanation of the present invention:
Fig. 1 is the structural representation of the embodiment of reflective input mouth mirror.
Fig. 2 is the structural representation of embodiment with input-only sealed ring type optical cavity of reflective input mouth mirror.
Fig. 3 is the structural representation of the embodiment of transmission-type input mouth mirror.
Fig. 4 is the structural representation of embodiment with input-only sealed ring type optical cavity of transmission-type input mouth mirror.
Fig. 5 is the structural representation of embodiment with input-only sealed ring type optical cavity of input port combined lens.
Fig. 6 is the apparatus structure schematic diagram that input-only sealed ring type optical cavity with transmission-type input mouth mirror is used to obtain the embodiment of intense light pulse.
Fig. 7 is the apparatus structure schematic diagram that input-only sealed ring type optical cavity with reflective input mouth mirror is used to improve the embodiment of shg efficiency.
Fig. 8 is that the input-only sealed ring type optical cavity with input port combined lens is used to improve the efficiency of light energy utilization of high frequency light modulating device, or reduces the apparatus structure schematic diagram of embodiment of the operating voltage of high frequency light modulation electric luminescent crystal.
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail:
Fig. 1 is the structural representation of an embodiment of reflective input mouth mirror.The material that the sheet base adopts aluminium, silver etc. to have the good optical reflectivity is made, or makes the sheet base with other material earlier, plates reflection enhancing coating after its surface texture is made again thereon to strengthen reflectivity.Surface at the sheet base makes numerous parallel isoceles triangle grooves, and the geometry of these grooves is identical.1 is one of them triangular groove among the figure, and the length on its base (among the figure 2) is much larger than incident wavelength (generally greater than two to three orders of magnitude of wavelength), and the angle of its two base angle (among the figure 3,4) is 30 degree.So two sides of each triangular groove have all become a tiny rectangular mirror, the normal of these two sides (5 is wherein towards the normal of the side in left side among the figure) all is 60 degree with the angle on sheet base macroscopic view plane.When a monochromatic collimated beam bundle from sheet base left side with each triangle left surface normal angle (the figure 6) when being the direction incident of 30 degree, equal the laws of geometrical optics of incidence angle according to angle of reflection (among the figure 7), incident light will be reflected to and the perpendicular direction in sheet base macroscopic view plane, simultaneously, because the incident direction of incident beam is parallel with each leg-of-mutton right side side strictness, so the incident beam in whole incoming cross-section all will project on the reflecting surface of effective leg-of-mutton left side, so be reflected to same direction entirely, thereby guarantee that this kind speculum can have the highest collection efficiency.In like manner, because each triangle is an isosceles triangle, when a monochromatic collimated beam bundle from sheet base right side when being the direction incident of 30 degree with each triangle right flank normal angle, also will be reflected to and the perpendicular direction in sheet base macroscopic view plane, and can guarantee to have the highest collection efficiency equally.Add that it is very little (for example when triangle base length is 1,000 times of green light wavelength that each leg-of-mutton yardstick is compared with whole base, if sheet sound stage width degree is 5 centimetres, then each leg-of-mutton length also only is one of percentage of sheet sound stage width degree), thereby can realize two bundles are reflexed to a same direction by the monochromatic collimated beam bundles of two different directions incidents, and along the purpose of same propagated.
An embodiment who is participated in the input-only sealed ring type optical cavity formed by this reflective input mouth mirror is shown in Fig. 2.Chamber outer light beam (among the figure 8) is from a side incident of input mouth mirror (the figure 9), reflection through the input mouth mirror enters in the chamber, incide the input mouth mirror from opposite side again through the transmission and the reflection of a set of lenses (among the figure 10,11) and two speculums (among the figure 12,13) then, through its reflection, then just in the chamber, begin a new round closed ring-like operation in ground along former same paths, and circulation so repeatedly.The effect of set of lenses is to offset the input mouth mirror at the expansion bundle of each reflex time to light beam, is included in odd number time circulation and the even number time circulation to make light beam expand bundle to the translation of a triangular groove width of the each translation in light beam both sides respectively.
Make that G is that light beam carries out once single-cycle light intensity gain coefficient (owing to be passive cavity, G is less than 1) in the chamber, and to establish light intensity be that the light beam of I is becoming I through circulation back light intensity in chamber
1, then should have
I
1=IG=IT
L1T
L2R
M1R
M2R
G(1) T in the formula
L1, T
L2Be respectively the light intensity transmitance of two lens (among the figure 10,11), R
M1, R
M2Be respectively the light intensity reflectivity of two speculums (among the figure 12,13), and R
GIt is the light intensity reflectivity of input mouth mirror.Two to three orders of magnitude because the scale ratio light wave of the triangular groove on input mouth mirror surface is grown up, so the diffraction effect of groove line is extremely faint (referring to document: Zhao Kaihua, the Zhong Xihua work, optics, BJ University Press, the first volume, 185 pages), its loss that causes can be ignored, and other ignores the absorption loss (find the optical frequency wave band of the negligible material of absorption loss for difficulty, two lens can be used the concave spherical mirror group instead and replace) of two lens.Employing is in the method for two surface plating anti-reflection films of lens, the transmitance of two lens can reach more than 99.9% (only considers monochromatic incident light, do not need the broadband), and employing is in the method for the surface of two speculums plating multilayer reflection enhancing coating, the reflectivity of two speculums also can reach more than 99.7% (referring to document: Yang Chenhua for monochromatic wavelength, Mei Suisheng, the Lin Junting chief editor, laser and infrared technique handbook, National Defense Industry Press, nineteen ninety, 105 pages--120 pages), because the yardstick of the triangular groove on input mouth mirror surface is much larger than lambda1-wavelength, so can not influence the accuracy of its surperficial geometry equally at its surface plating reflection enhancing coating acquisition high reflectance, so the ring-like chamber for shown in Figure 2 can obtain the gain coefficient up to 0.99.
Fig. 3 is the structural representation of an embodiment of transmission-type input mouth mirror.The sheet base adopts glass, quartz etc. to make for the material that the optical wavelength of being considered has the good optical transmissivity.Also make numerous parallel isoceles triangle grooves on a surface of sheet base, and the geometry of each groove is identical.14 is one of them triangular groove among the figure, and the length on its base (among the figure 15) is also much larger than incident wavelength.
Be provided with the lower-left side incident of a monochromatic collimated beam bundle (among the figure 16) from the sheet base plane, the angle of the baseplane of itself and sheet base is θ
i(among the figure 17), enter the sheet base after, the refraction angle of light beam is θ
d(among the figure 18), in order to obtain maximum luminous energy collection efficiency, require the left surface (among the figure 20) of the propagation path of light beam in the sheet base (among the figure 19) and triangular groove parallel, after also requiring this light beam to appear simultaneously from each little triangle refracting prisms refraction, can be along propagating with the perpendicular direction in macroscopical plane of sheet base (among the figure 21), need satisfy following relationship (sign of angle is pressed uniform rules and is determined in the formula for this reason, referring to document: volumes such as home country's light, optics, the People's Education Publishing House, 1978,40 pages--41 pages)
θ
d+θ
b＝90°
θ
d-α＝-β
θ
b＝-β (2)
n′sin(90°-θ
i)＝nsinθ
d
θ in nsin α=n ' sin β formula
bIt is the base angle angle (among the figure 22,23) of each vee gutter, α is the angle (among the figure 24) of sheet base inner light beam and each side, triangle right side normal, β is an outgoing beam (among the figure 25) and the angle of this side normal (among the figure 26), n is the refractive index of sheet base medium, and n ' is the refractive index of the outer medium of sheet base.Simultaneous solution (2) formula obtains
Sin θ
b=n '+[(n ')
2+ 8n
2]
1/2)/4n (3) for example selects the quartz plate base for use so the angle at each leg-of-mutton two base angle need be definite by the calculating of (3) formula according to the refractive index of sheet base, substitution n=1.538, and n '=1 (establishing the outer medium of sheet base is air) obtains θ
bEqual 62.6 degree.So, as a monochromatic collimated beam bundle during from the lower-left side incident of sheet base plane, just be refracted and along with the perpendicular direction outgoing in plane of sheet base macroscopic view, and can guarantee that the incident beam in whole incoming cross-section all will be refracted into a same direction simultaneously, thereby obtain the highest collection efficiency.In like manner, when a monochromatic collimated beam bundle during, also will be refracted into and the perpendicular direction in sheet base macroscopic view plane, and can guarantee to have the highest collection efficiency equally from the symmetry direction incident of the lower right side of sheet base plane.It also is very little that each the leg-of-mutton length that adds the sheet primary surface is compared with the sheet base, thereby can realize two bundles are refracted to a same direction by the monochromatic collimated beam bundles of two different directions incidents, and along the purpose of same propagated.
An embodiment who is participated in the input-only sealed ring type optical cavity formed by this transmission-type input mouth mirror is shown in Fig. 4.Chamber outer light beam (among the figure 27) is from a side incident at input mouth mirror (the figure 28) back side, refraction through the input mouth mirror enters in the chamber, then through a set of lenses (among the figure 29,30) and three speculums (among the figure 31,32,33, wherein 31 and 32 is two speculums that utilize total internal reflection) transmission and reflection incide the input mouth mirror from the opposite side at the back side again, after its refraction, just in the chamber, begin new round ground and circulates along former same paths.The effect of set of lenses also is for offset input mouth mirror expansion bundle to light beam when reflecting, make light beam expand bundle to the translation of a triangular groove width of side translation when comprising each the refraction at every turn.
Making still that G is that light beam carries out once single-cycle light intensity gain coefficient in this kind chamber, is that the light beam of I is becoming I through circulation back light intensity in chamber because of light intensity
1So, have
I
1=IG=IT
L1T
L2R
M1R
M2R
M3R
G(4) T in the formula
L1, T
L2Be respectively the light intensity transmitance of two lens (among the figure 29,30), R
M1, R
M2And R
M3Be respectively the light intensity reflectivity of three speculums (among the figure 31,32,33), and R
GIt is the light intensity transmissivity of input mouth mirror.As above identical to the analysis in reflective chamber, also ignore the caused loss of absorption of diffraction and lens, total internal reflection type speculum and the input mouth mirror material of triangular groove line.Adopt the method for having stated at the surface of each light beam transmission plating anti-reflection film, the method at the surface of beam reflection plating multilayer reflection enhancing coating then can make T
L1=T
L2=R
M1=R
M2=99.9%, R
M3=99.7%, the same because yardstick of the triangular groove on input mouth mirror surface much larger than lambda1-wavelength, does not influence the accuracy of its surperficial geometry, thereby can make R so can plate anti-reflection film on its surface yet
G=99.9%, so, can obtain gain coefficient up to 0.992 for ring-like chamber shown in Figure 4.
Fig. 5 is the structural representation of embodiment with input-only sealed ring type optical cavity of input port combined lens.Described input port combined lens, form by three graded index convergent lenses, wherein two (among the figure 34,35) places the two-port place of an optical fibre ring (figure 36) respectively, make the divergent beams of optical fibre ring output output thus be converged to directional light, after outside optical fiber, propagating certain distance, assemble again again and from then on the input of optical fibre ring import this optical fiber again.Other has the transport optical fiber of an optical fiber (among the figure 37) as the chamber outer light beam, the output of its output and optical fibre ring is pressed close to, so that make the divergent beams that transport optical fiber output thus, after assembling, the convergent lens (figure 38) that places its port by the 3rd also becomes collimated light beam, and the also convergence of the lens through placing the optical fibre ring input and import optical fibre ring after propagating certain distance.So the light beam in the optical fibre ring can only circulate in the optical fibre ring chamber, and the light energy outside the chamber is constantly injected, thereby has just formed the input-only sealed ring type optical cavity with input port combined lens.For making by the light beam of optical fibre ring output output and the light beam of exporting by the output that transports optical fiber outside the chamber, incident optical fibre ring smoothly is so need the beam cross section overall width behind collimation of above-mentioned two output beams to be less than or equal to effective clear aperature of the convergent lens before placing the optical fibre ring input.
Make once more that G is that light beam carries out once single-cycle light intensity gain coefficient in this optical fiber cavity, and still to establish light intensity be that the light beam of I is becoming I through circulation back light intensity in chamber
1, just have
I
1=IG=IT
L1T
L2T
F(5) T in the formula
L1, T
L2Be respectively the light intensity transmitance of two lens (among the figure 34,35), T
FIt is the transmitance of optical fibre ring.It is very little that the loss of modern optical fiber has been done, for example be low to moderate 0.2 decibel every kilometer (referring to document: volumes such as Tan Guanrong for some wave band, quantum electronics, Higher Education Publishing House, 1988,346 pages), if optical fibre ring length is 1 meter, then its loss is adopted the measure at optical fibre ring two-port surface and three lens surfaces plating multilayer anti-reflection film, so can make T less than one thousandth
L1=T
L2=0.999, and T
F=0.997, so, can obtain gain coefficient up to 0.995 for annular optical fiber chamber shown in Figure 5.The caused losses such as absorption of two lens materials have also been ignored in the analysis.
Fig. 6 is the apparatus structure schematic diagram that input-only sealed ring type optical cavity with transmission-type input mouth mirror is used to obtain the embodiment of intense light pulse.39 is that an electricity of putting into the chamber light path causes light polarization face rotating crystal among the figure, 40 is Glans among the figure--Thomson type polarization splitting prism is (referring to document: Yang Chenhua, Mei Suisheng, the Lin Junting chief editor, laser and infrared technique handbook, National Defense Industry Press, nineteen ninety, 209 pages--214 pages), they form the direction of beam propagation switching device shifter that places in the chamber.Be provided with light pulse (pulse duration was 30 nanoseconds) and begin to enter in the chamber from input mouth mirror (the figure 41) from time T=0 o'clock, and to establish this pulsed light beam be polarised light that its polarization direction is perpendicular to paper once toning Q.This light beam through two complete in the reflection of transreflector, the incident electrooptic crystal, this moment, electricity closed not making alive of crystal, therefore light beam does not rotate by its rear polarizer face, enter devating prism as ordinary light after the outgoing and along straightline propagation, circulate in the chamber by mirror reflects, the refraction of input mouth mirror again.If chamber length is 30 centimetres, then chamber length is a thirtieth of pulse length, because the continuous remittance of chamber outer light beam, just chamber inner light beam intensity constantly strengthens.As time T=30 during nanosecond, chamber outer light beam input finishes, this moment is if add to electrooptic crystal with half-wave voltage rapidly, then after this be rotated by 90 degrees entirely by its plane of polarization of light beam, become extraordinary ray and enter devating prism, thereby total reflection takes place and outside the output cavity, on the oblique interface in prism in a cycle period because the chamber inner light beam just can all be totally lost, then the emergent light pulse length also is 30 centimetres, thereby pulse duration was compressed into for 1 nanosecond.Before state, the single cycle gain G in this kind chamber equals 0.992, considers that electricity closes the insertion loss of crystal and devating prism, desirable G equals 0.99.Because the light beam section in the initial incident chamber has circulated in the chamber 30 times, and the light beam section in the last incident chamber has circulated in the chamber once, so the total losses of whole pulse in the chamber should be
＜(0.01+0.02+ ... + 0.29+0.3)/average power that 30=0.15 (6) establishes the accent Q light pulse of incident is that 10 megawatts are (referring to document: Yang Chenhua, Mei Suisheng, the Lin Junting chief editor, laser and infrared technique handbook, National Defense Industry Press, nineteen ninety, 345 pages) because back 30 circulation superpositions of light intensity in its incident chamber, with and total losses be 15%, then the average power of the light pulse of output can reach 255 megawatts after this ring-like chamber compression, and its single pulse energy is 255 millijoules.
Fig. 7 is the apparatus structure schematic diagram that input-only sealed ring type optical cavity with reflective input mouth mirror is used to improve the embodiment of shg efficiency, 42 is the frequency-doubled conversion working medias that are positioned in the chamber among the figure, and 43 is the light-splitting device-chromatic dispersion prisms that are positioned in the chamber among the figure.If the first-harmonic light beam in the incident chamber, its frequency are ω, intensity is I
iThis light beam is entered in the chamber by input mouth mirror (among the figure 44) reflection, and after the bundle set of lenses that contracts (among the figure 45,46), beam cross section reduces, and power density strengthens, the medium of incident frequency multiplication then, and the shg efficiency of establishing this working media is μ.By behind the dispersing prism, the harmonic optcial beam deviation that frequency wherein becomes 2 ω is bigger by the light beam of frequency multiplication medium outgoing, presses among the figure outside the output cavity of direction shown in 47, makes that its intensity is I
O1, and the remaining first-harmonic light beam that does not obtain changing in the incident light (makes that its intensity is I
I1), deviation is less, and they along light path circulation in the chamber, and are able to the medium of incident frequency multiplication once more and change after speculum (among the figure 48) reflection, and the harmonic optcial beam after the conversion again outside the output cavity again makes that its intensity is I
O2, and remaining once more first-harmonic light beam (makes that its intensity is I
I2), again along light path circulation in the chamber, and can obtain conversion again, this process constantly repeats.If ring-like chamber is lossless, obviously for frequency multiplication working media that no matter why μ is worth, after using the ring-like chamber of this kind, can both make the light beam in the incident chamber become the harmonic wave outgoing entirely, thereby make shg efficiency bring up to 1, for the ring-like chamber that has loss of reality, then the intensity and the remaining fundamental wave beam intensity of light beam harmonic optcial beam of output in each conversion are
I
o1＝I
iR
GT
L1T
L2T
CμT
P
I
i1＝I
iR
GT
L1T
L2 -T
C(1-μ)T
P
I
o2＝I
i1Gμ
I
i2＝I
i1G(1-μ)
I
o3＝I
i2Gμ
I
i3＝I
i2G(1-μ) (7)
I
o4＝I
i3Gμ
I
i4＝I
i3G(1-μ)
. ＝ .
. ＝ .
R in .=. the formula
GBe the light intensity reflectivity of input mouth mirror, T
L1, T
L2Be the light intensity transmissivity of two convergent lenses (among the figure 45,46), T
CBe the light intensity transmissivity of frequency multiplication working media, T
PBe the light intensity transmissivity of dispersing prism, in this ring-like chamber, carry out once single-cycle light intensity gain coefficient and G is a light beam
G=R
GT
L1T
L2T
CT
PR
L1T
L3T
L4R
L2(8) R in the formula
L1, R
L2Be the light intensity reflectivity of two speculums (among the figure 48,49), T
L3, T
L4It is the light intensity transmissivity of two lens forming the beam expanding lens group (among the figure 50,51).
The light beam overall strength of the harmonic wave that output cavity is outer should be the superposition of the humorous intensity of wave exported in multiple conversions, promptly
I
o=I
O1+ I
O2+ I
O3+ ... I
O ∞(9) in above-mentioned analysis for the input-only sealed ring type optical cavity with reflective input mouth mirror, known taking measures can make R
G=R
L1=R
L2=0.997, T
L1=T
L2=T
C=T
P=T
L3=T
L4=0.999, so G is 0.985.If the beam intensity by input outside the chamber is unit strength (being that intensity is 1), then when the shg efficiency μ of frequency multiplication working media equals 0.4, and when only needing to consider the harmonic wave intensity addition of output in preceding ten conversions, just can be regarded as to such an extent that the synthetic intensity of the outer harmonic wave of output cavity is 0.95 by (7) and (9) formula, thereby use this kind input-only sealed ring type chamber, the luminous power conversion efficiency of optical frequency-doubling can be brought up to 0.95 by 0.4.The raising that adds light intensity in the epicoele also can be strengthened the non-linear conversion effect of frequency multiplication working media, thereby helps further to improve total frequency-doubling conversion efficiency.
Fig. 8 is that the input-only sealed ring type optical cavity with input port combined lens is used for reducing the apparatus structure schematic diagram that high frequency light modulating device electricity causes the embodiment of light polarization face rotating media driving voltage, 52 is that the electricity that is positioned in the chamber causes plane of polarization rotating media--electrooptic crystal among the figure, and 53 is Glans among the figure--Thomson type polarization splitting prism.Be provided with a light beam transports optical fiber (the figure 54) outside the chamber output output, establish its polarization direction perpendicular to paper.This light beam is through the convergence of convergent lens (among the figure 55), become directional light incident electrooptic crystal, if electricity closes not making alive of crystal, then light beam does not rotate by its rear polarizer face, enter devating prism as ordinary light after the outgoing and along straightline propagation, assemble and the input optical fibre ring by convergent lens (among the figure 56) again, after other end output, enter in the optical fiber cavity through convergent lens, electrooptic crystal, devating prism etc. again and circulate.Because the continuous remittance of chamber outer light beam, chamber inner light beam intensity constantly strengthens, when the energy loss speed of the input rate and optical fiber cavity self of ambient light energy equates and reach a balance stable state peak.If by the light beam light intensity in the input cavity outside the chamber is I
i, the single cycle light intensity gain of light beam in the chamber is G, then its single cycle intensity loss is L=1-G.If the balance stable state light intensity value in the chamber is I
M, then have
I
i＝LI
M＝(1-G)I
M (10)
If operating voltage is added to electrooptic crystal, then the plane of polarization of light beam by it can be rotated, after the part that wherein becomes extraordinary ray enters devating prism, total reflection takes place on can the oblique interface in prism and outside the output cavity, and ordinary light partly enters still straightline propagation behind the devating prism.If the outer beam intensity of output cavity is I
o, for the electrooptic crystal of vertical use, then have following relation (referring to document: husband's work in the A. Asia, Liu Songhao etc. translate, quantum electronics, Shanghai science tech publishing house, nineteen eighty-three, 350 pages--351 pages)
I
o=I
M[sin (π V/2V
π)]
2(11) V in the formula
πBe the required half-wave voltage of electrooptic crystal, V is the driving voltage that adds to electrooptic crystal.If the peak strength of the light beam of our needs ring-like thus chamber output equals the peak strength by the light beam of input outside the chamber, then have
I
i=I
o=I
M[sin (π V/2V
π)]
2(12) substitution (10) formula has
V=(2V
π/ π) arcsin[(L)
0.5] (13) from above-mentioned analysis for this optical fiber cavity, the light beam gain by one path G in known this kind chamber is 0.995, considers the insertion loss of electrooptic crystal and devating prism, desirable G=0.99, so L=0.01, substitution (13) formula obtains
V=0.064V
π(14) as seen, because the enhancing of light intensity in the ring-like chamber, the driving voltage of the required former amplitude light intensity of output of electrooptic crystal can reduce in the modulating device, thereby can reduce the operating voltage of electrooptic crystal in the high frequency light modulating device.
For the electrooptic crystal of horizontal use, similar conclusion is also arranged, because of proof procedure roughly the same, do not give unnecessary details herein.
Fig. 8 also is the apparatus structure schematic diagram of the embodiment of input-only sealed ring type optical cavity with the input port combined lens efficiency of light energy utilization that is used to improve the high frequency light modulating device, obviously, when thereby making alive is not equivalent to modulating device and closes at electrooptic crystal, beam energy circulates along chamber inner ring type light path, thereby be able to temporary transient storage, and incident electrooptic crystal and being reused once more, thereby if this moment electrooptic crystal add the voltage modulating device open just exportable, so can improve the utilance of high frequency light modulating device to incident optical energy.Its concrete improvement value to the incident optical energy utilance is decided according to the duty cycle of switching of light modulation, and dutyfactor value R (R=switch opens time/switch shut-in time) is more little, and then improvement value is big more.
Three kinds of input-only sealed ring type optical cavity structures provided by the present invention can be under total design prerequisite of the present invention, according to existing technique known change, for example will have speculum in the sealing ring-type optical chamber of reflective input mouth mirror change into complete in transreflector, to have the expansion bundle in the sealing ring-type optical chamber of reflective input mouth mirror and the bundle set of lenses that contracts all changes concave spherical surface formula reflector group into, transmission-type input mouth mirror and optical fibre ring will be constituted input-only sealed ring type optical cavity etc.
Three kinds of input-only sealed ring type optical cavities provided by the present invention, all can be used to obtain intense light pulse, improve the non-line conversion of optics efficient, improve the efficiency of light energy utilization of high frequency light modulating device and reduce driving voltage, driving magnetic field or the distribution of light intensity of electricity, magnetic or photic plane of polarization rotating media in the high frequency light modulating device.For some application, can use two or two kinds simultaneously, even two or two or more above-mentioned ring-like chambeies, for example improve the difference frequency conversion or and the application of the efficient of conversion frequently in.
Input-only sealed ring type optical cavity provided by the present invention, the application of the aspects such as driving voltage, driving magnetic field or distribution of light intensity of electricity, magnetic or photic plane of polarization rotating media in obtaining intense light pulse, raising optical nonlinearity conversion efficiency, the efficiency of light energy utilization that improves the high frequency light modulating device and reduction high frequency light modulating device, not only can be used for visible light wave range, also can be used for infrared or ultraviolet or even the shorter frequency band of wavelength.
Claims (10)
1. input-only sealed ring type optical cavity that stores beam energy, superimposed light beam intensity, have and make two bundle directions or the different light beams in path merge into input mouth mirror or input port combined lens equidirectional, that propagate with the path, itself and beam-shrinked mirror, reflector group or optical fibre ring constitute ring-like optical cavity, it is characterized in that: it is ring-like that light path constitutes unidirectional blocking in the chamber, it has only the light beam input port, and does not have light beam output port (for the light beam that moves on the inner ring type light path of chamber).
2. input-only sealed ring type optical cavity according to claim 1, it is characterized in that: described input mouth mirror, be to adopt optical material to make the sheet base with good reflection rate, make numerous parallel and isoceles triangle grooves that shape is identical in surface thereof, the angle at two base angles of each triangular groove is 30 degree, makes it become a kind of bi-directional symmetrical speculum, and the sheet base also can be used other material earlier, after said structure was made, plating increased anti-film thereon again.
3. input-only sealed ring type optical cavity according to claim 1, it is characterized in that: described input mouth mirror, be to adopt optical material to make the sheet base, make numerous parallel and isoceles triangle grooves that shape is identical, the angle θ at two base angles of each triangular groove in surface thereof with good transmissivity
bBe to decide, specifically calculate by following formula according to convergeing to the requirement of same direction and the maximum luminous energy collection efficiency of acquisition after the symmetrical incident beam refraction of two bundles is seen through
Sin θ
b=n '+[(n ')
2+ 8n
2]
1/2N is the refractive index of sheet base medium in the }/4n formula, and n ' is the refractive index of the outer medium of sheet base, and this makes it become a kind of bi-directional symmetrical refracting telescope, after said structure is made, can plate anti-reflection film thereon.
4. input-only sealed ring type optical cavity according to claim 1, it is characterized in that: described input port combined lens, form by one group of convergent lens (convex lens or gradient-index lens), place the two-port place of an optical fibre ring and the output port place that another chamber outer light beam transports optical fiber respectively, the focal length of each convergent lens or equivalent focal length are determined according to following requirement: make the effective clear aperature that is less than or equal to the convergent lens that places the optical fibre ring input via the light beam total cross section that places optical fibre ring output and the lens that transport fiber-optic output to assemble the collimated light beam of outgoing, can plate anti-reflection film on the surface of each lens and each end face of optical fiber.
5. purposes that is used to improve the optical nonlinearity conversion efficiency according to claim 1 or 2 or 3 or 4 described input-only sealed ring type optical cavities, it is characterized in that: the beam energy that utilizes described input-only sealed ring type optical cavity to make not obtain changing circulates along chamber inner ring type light path, and repeatedly incident non-linear conversion working media and being changed again, or utilize also that light intensity strengthens the effect that non-linear transformation efficiency is improved in the chamber.
6. device of implementing purposes according to claim 5, it is characterized in that: on chamber inner ring type light path, place optical nonlinearity conversion work medium or and light-splitting device according to claim 1 or 2 or 3 or 4 described input-only sealed ring type optical cavities.
7. purposes that is used to improve the efficiency of light energy utilization of high frequency light modulation according to claim 1 or 2 or 3 or 4 described input-only sealed ring type optical cavities, it is characterized in that: utilize beam energy that described input-only sealed ring type optical cavity makes the output of not modulated device along circulation of chamber inner ring type light path and temporary transient the storage, and incident modulating device and being reused once more.
8. purposes that is used to reduce required driving voltage of working media or driving magnetic field in the high frequency light modulating device according to claim 1 or 2 or 3 or 4 described input-only sealed ring type optical cavities or drives distribution of light intensity, it is characterized in that: utilize described input-only sealed ring type optical cavity to make the light beam stack that in the chamber, circulates, thereby the light intensity of these media of incident is strengthened significantly, make the driving voltage or the driving magnetic field of the former amplitude light intensity of its required output or drive distribution of light intensity and reduce.
9. purposes that is used to obtain intense light pulse according to claim 1 or 2 or 3 or 4 described input-only sealed ring type optical cavities, it is characterized in that: utilize described input-only sealed ring type optical cavity to make the light beam of incident outside the chamber, by circulation in the chamber light intensity stack, pulsewidth are shortened, then export by a direction of beam propagation switching device shifter.
10. device according to claim 7 or 8 or 9 described purposes, it is characterized in that: on chamber inner ring type light path, place electricity and cause or mangneto or photic plane of polarization rotating media and polarized light splitting device according to claim 1 or 2 or 3 or 4 described input-only sealed ring type optical cavities.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 95105306 CN1136719A (en) | 1995-05-22 | 1995-05-22 | Input-only sealed ring type optical cavity and its use |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 95105306 CN1136719A (en) | 1995-05-22 | 1995-05-22 | Input-only sealed ring type optical cavity and its use |
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|---|---|
| CN1136719A true CN1136719A (en) | 1996-11-27 |
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|---|---|---|---|
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107942500A (en) * | 2018-01-03 | 2018-04-20 | 任汉程 | A kind of laser minimizes energy supposition system |
| CN110455829A (en) * | 2019-08-19 | 2019-11-15 | 电子科技大学 | High-Power Microwave is to the non-thermal influencing mechanism extraction system of dielectric substance and method |
| CN110571638A (en) * | 2019-08-16 | 2019-12-13 | 华中科技大学 | Broadband double-oscillation parametric oscillator for reflecting injected pump light |
-
1995
- 1995-05-22 CN CN 95105306 patent/CN1136719A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107942500A (en) * | 2018-01-03 | 2018-04-20 | 任汉程 | A kind of laser minimizes energy supposition system |
| CN107942500B (en) * | 2018-01-03 | 2020-04-24 | 任汉程 | Laser miniaturization energy superposition system |
| CN110571638A (en) * | 2019-08-16 | 2019-12-13 | 华中科技大学 | Broadband double-oscillation parametric oscillator for reflecting injected pump light |
| CN110455829A (en) * | 2019-08-19 | 2019-11-15 | 电子科技大学 | High-Power Microwave is to the non-thermal influencing mechanism extraction system of dielectric substance and method |
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