CN110323662A - Passive mode-locking resonant cavity and laser - Google Patents
Passive mode-locking resonant cavity and laser Download PDFInfo
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- CN110323662A CN110323662A CN201810287293.4A CN201810287293A CN110323662A CN 110323662 A CN110323662 A CN 110323662A CN 201810287293 A CN201810287293 A CN 201810287293A CN 110323662 A CN110323662 A CN 110323662A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/08004—Construction or shape of optical resonators or components thereof incorporating a dispersive element, e.g. a prism for wavelength selection
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/08072—Thermal lensing or thermally induced birefringence; Compensation thereof
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
- H01S3/0811—Construction or shape of optical resonators or components thereof comprising three or more reflectors incorporating a dispersive element, e.g. a prism for wavelength selection
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/11—Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping
- H01S3/1106—Mode locking
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
- H01S3/136—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling devices placed within the cavity
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Abstract
The present invention is suitable for resonant cavity technical field, provide a kind of passive mode-locking resonant cavity, resonant cavity is both arms astigmatic compensation chamber, and including the astigmatic compensation unit and its π circle and the tangent thermal lens of output plane mirror in pumping source, mode-locking device and output plane mirror, the optical path being set between mode-locking device and output plane mirror；Each astigmatic compensation unit includes at least two curved mirrors；The position of each curved mirror is determined by propagating circle graphing method according to the inclination angle of spot radius size, the focal length of each curved mirror and an at least curved mirror.The passive mode-locking resonant cavity is by being arranged astigmatic compensation unit in the optical path between mode-locking device and output plane mirror, so that the intracavitary astigmatism of the both arms astigmatic compensation is compensated, the position that each curved mirror in astigmatic compensation unit is determined using propagation circle graphing method, so that astigmatic compensation effect is best；By the way that thermal lens is arranged in passive mode-locking resonant cavity, so that the hot spot of the light beam before output plane mirror changes minimum, the propagation characteristic of light beam is stablized.
Description
Technical field
The invention belongs to field of laser device technology more particularly to a kind of passive mode-locking resonant cavity and have the passive mode-locking humorous
The laser of vibration chamber.
Background technique
Resonant cavity is the important component of solid state laser, the parameter of output laser is directly affected, such as output power, light
Beam quality and stability etc..
Resonant cavity mostly uses greatly refrative cavity in solid laser with active-passive lock mould, and lesser focusing not only may be implemented in refrative cavity
Hot spot can also be folded in longer chamber length within lesser space, keep the structure of laser more compact.However, rolling over
In folded chamber, curved reflector slant setting will certainly generate astigmatism, and laser beam quality is caused to decline.In solid state laser,
Some is used to be converted into exciting light pump energy, is largely converted into heat, these heats are disperse in laser
In crystal, crystals lead to temperature gradient distribution in laser bar with surface temperature difference, to form thermal lensing effect.Low function
When rate pumps, thermal lensing effect is unobvious, can ignore influence.High-power output is obtained, pump power must be improved also, this
When thermal lensing effect highly significant, the variation that thermal lens heat is disturbed in resonant cavity can stability to output laser and intracavitary hot spot
Size variation has an impact.Resonator design method usually insensitive using single astigmatic compensation or thermal lens, such as
Abcd matrix method, q parameter etc., but mode locking pulse output continual and steady in order to obtain has become urgent problem to be solved in the industry.
Summary of the invention
The purpose of the present invention is to provide a kind of passive mode-locking resonant cavities, while considering that astigmatic compensation and thermal lens are insensitive
Factor, it is intended to the technical issues of how resonant cavity in the prior art obtains continual and steady mode locking pulse output solved.
The invention is realized in this way a kind of passive mode-locking resonant cavity, the resonant cavity is both arms astigmatic compensation chamber, and is wrapped
Include that pumping source, the mode-locking device being set in the end walls of the both arms astigmatic compensation chamber and output plane mirror, at least one sets
The astigmatic compensation unit in optical path that is placed between the mode-locking device and the output plane mirror and it is set to the mode locking
Between device and the output plane mirror and its π justifies and the tangent thermal lens of the output plane mirror；Each astigmatic compensation list
Member includes at least two curved mirrors, and the hot spot of meridian plane and sagittal surface on the curved mirror of the output plane mirror is big
It is small identical；The pump light of the pumping source output is incident in the mode-locking device and generates radius in the mode-locking device
ω0Hot spot, according to the spot radius size, the inclination angle of the focal length of each curved mirror and at least one curved mirror
The position of each curved mirror is determined by propagating circle graphing method.
Further, the curved mirror includes the first surface reflecting mirror that distance is L1 between the mode-locking device, institute
State the beam waist parameter at mode-locking device:
Wherein, ω0For the radius of the hot spot, λ is the wavelength of the hot spot；
The parameter b with a tight waist of side focus is calculated using formula (1)0；
It crosses the side focus and is tangential on the first surface reflection mirror drawing circle π with optical axis1, the radius of the circle is described the
Spot size at one curved reflector；
It crosses the side focus and justifies with the tangent picture of the front surface of the first surface reflecting mirror, the radius of the circle is described the
Wave-front curvature radius at one curved reflector.
Further, the focal length of the first surface reflecting mirror is f1And inclination angle is θ1, calculated as following formula described in
Focal length f of the first surface reflecting mirror in its meridian plane and sagittal surfacetAnd fs:
ft=f*cos θ (2)
Wherein, f is the focal length of the curved mirror, and θ is the inclination angle of the curved mirror；
And according to the relationship of radius of curvature after wavefront wave:
Wherein, R is wave-front curvature radius, and R ' is radius of curvature after wave；Described is calculated by formula (2), (3) and (4)
The radius R of radius of curvature and its meridian plane and sagittal surface after the wave of one curved reflectort' and Rs', respectively with the meridian plane and
The radius R of the sagittal surfacet' and Rs' it is diameter and the center of circle in optical axis upper drawing circle, and the circle and the first surface reflecting mirror
Rear surface is tangent, the circle and the round π1Intersection point be the meridian plane and sagittal surface side focus F1tAnd F1s；
According to side focus F1tAnd F1sParameter b with a tight waist1tAnd b1s, aforesaid operations are repeated, the (n-1)th curved reflector is obtained
Parameter b with a tight waist(n-1)tAnd b(n-1)s；Thereby determine that the second curved reflector to the position of (n-1)th curved reflector, wherein n
For the positive integer greater than 2.
Further, the side focus F of excessively described (n-1)th curved reflector(n-1)tAnd F(n-1)sAnd with the tangent picture of the optical axis
Circle πn, in circle πnWith the n-th curved reflector is placed at the point of contact of the optical axis, meridian plane at n-th curved reflector and
The spot size of the light beam of sagittal surface is identical, and the coincidence with a tight waist of the meridian plane and sagittal surface of the n-th curved reflector image space,
Wherein, n is the positive integer greater than 2.
Further, radius of curvature R after the wave of the meridian plane at n-th curved reflector and sagittal surfacetAnd RsPhase
Together, it can be obtained according to formula (2) (3) (4) synthesis:
Wherein, fnFor the focal length of the n-th camber reflection lens, θnFor the inclination angle of the n-th camber reflection lens, n is greater than 2
Positive integer.
Further, the round tangent and points of tangency of π circle at the thermal lens of the σ of the flat output mirror is located at described the
The image side focal point of n curved reflector.
Further, the thermal lens makees thin lens processing.
The present invention also provides a kind of lasers, including above-mentioned passive mode-locking resonant cavity.
The present invention compared with the existing technology have the technical effect that the passive mode-locking resonant cavity by the mode-locking device and
The astigmatic compensation unit is set in the optical path between the output plane mirror, so that the intracavitary astigmatism of the both arms astigmatic compensation obtains
To compensation, specifically, the position of each curved mirror in the astigmatic compensation unit is determined using propagation circle graphing method, so that picture
Scattered compensation effect is best, according to spot radius, each curved mirror of the pump light of pumping source output in the mode-locking device
Focal length and the curved mirror tilt angle and using propagate circle graphing method will each curved mirror position determine under
Come, obtains optimal astigmatic compensation effect；In addition, by the way that thermal lens, and the heat are arranged in the passive mode-locking resonant cavity
The π circle of lens is tangent with the output plane mirror, so that the hot spot of the light beam before the output plane mirror changes minimum, light beam
Propagation characteristic is stablized.
Detailed description of the invention
In order to illustrate the technical solution of the embodiments of the present invention more clearly, below will be to the embodiment of the present invention or the prior art
Attached drawing needed in description is briefly described, it should be apparent that, drawings described below is only of the invention
Some embodiments for those of ordinary skill in the art without creative efforts, can also be according to this
A little attached drawings obtain other attached drawings.
Fig. 1 is that the embodiment of the present invention provides the structure principle chart of passive mode-locking resonant cavity；
Fig. 2 be the embodiment of the present invention provide passive mode-locking resonant cavity using propagate circle graphing method determine each curved mirror position
Structural schematic diagram；
Fig. 3 is the structure principle chart for the passive mode-locking resonant cavity that a specific embodiment of the invention provides；
Fig. 4 is that thermal focal length changes dynamic analysis figure in passive mode-locking device provided in an embodiment of the present invention；
Fig. 5 is to carry out 20 DEG C of output pulses of water temperature in mode locking experiment to passive mode-locking resonant cavity provided in an embodiment of the present invention
Sequence chart；
Fig. 6 is that 15 DEG C of left side water temperature output in mode locking experiment is carried out to passive mode-locking resonant cavity provided in an embodiment of the present invention
25 DEG C of output pulse sequences of pulse train and the right water temperature；
Fig. 7 be to passive mode-locking resonant cavity provided in an embodiment of the present invention carry out mode locking experiment under room temperature (20 DEG C) not
With pumping current near field far field output facula figure；
Fig. 8 is to different water temperatures in passive mode-locking resonant cavity provided in an embodiment of the present invention progress mode locking experiment to two kinds of chambers
The influence comparison chart of type output power；
Fig. 9 is to two kinds of chambers under three kinds of water temperatures in passive mode-locking resonant cavity provided in an embodiment of the present invention progress mode locking experiment
The stability comparison chart of type output power；
Figure 10 is to carry out pumping current 10A in mode locking experiment to passive mode-locking resonant cavity provided in an embodiment of the present invention to be lauched
Influence comparison chart of the temperature to output power.
Specific embodiment
The embodiment of the present invention is described below in detail, examples of the embodiments are shown in the accompanying drawings, wherein from beginning to end
Same or similar label indicates same or similar element or element with the same or similar functions.Below with reference to attached
The embodiment of figure description is exemplary, it is intended to is used to explain the present invention, and is not considered as limiting the invention.
In the description of the present invention, it is to be understood that, term " length ", " width ", "upper", "lower", "front", "rear",
The orientation or positional relationship of the instructions such as "left", "right", "vertical", "horizontal", "top", "bottom" "inner", "outside" is based on attached drawing institute
The orientation or positional relationship shown, is merely for convenience of description of the present invention and simplification of the description, rather than the dress of indication or suggestion meaning
It sets or element must have a particular orientation, be constructed and operated in a specific orientation, therefore should not be understood as to limit of the invention
System.
In addition, term " first ", " second " are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance
Or implicitly indicate the quantity of indicated technical characteristic.Define " first " as a result, the feature of " second " can be expressed or
Implicitly include one or more of the features.In the description of the present invention, the meaning of " plurality " is two or more,
Unless otherwise specifically defined.
In the present invention unless specifically defined or limited otherwise, term " installation ", " connected ", " connection ", " fixation " etc.
Term shall be understood in a broad sense, for example, it may be being fixedly connected, may be a detachable connection, or integral；It can be mechanical connect
It connects, is also possible to be electrically connected；It can be directly connected, can also can be in two elements indirectly connected through an intermediary
The interaction relationship of the connection in portion or two elements.It for the ordinary skill in the art, can be according to specific feelings
Condition understands the concrete meaning of above-mentioned term in the present invention.
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.
Fig. 1 to Fig. 4 is please referred to, the embodiment of the invention provides a kind of passive mode-locking resonant cavity, the resonant cavity is both arms
Astigmatic compensation chamber, and including pumping source, the mode-locking device M that is set in the end walls of the both arms astigmatic compensation chamber0And output
Plane mirror Mout, at least one be set to the mode-locking device M0With the output plane mirror MoutBetween optical path on astigmatism mend
It repays unit and is set to the mode-locking device M0With the output plane mirror MoutBetween and its π it is round with the output plane mirror
MoutTangent thermal lens Ft；Each astigmatic compensation unit includes at least two curved mirrors, close to the output plane mirror Mout
The curved mirror on meridian plane it is identical with the spot size of sagittal surface；The pump light of the pumping source output is incident to described
Mode-locking device M0In and in the mode-locking device M0Middle generation radius is ω0Hot spot, according to the spot radius size, each institute
The inclination angle of the focal length and at least one curved mirror of stating curved mirror determines each curved mirror by propagating circle graphing method
Position.
Passive mode-locking resonant cavity provided in an embodiment of the present invention passes through in the mode-locking device M0With the output plane mirror
MoutBetween optical path on the astigmatic compensation unit is set so that the intracavitary astigmatism of the both arms astigmatic compensation is compensated, specifically
Ground determines the position of each curved mirror in the astigmatic compensation unit using propagation circle graphing method, so that astigmatic compensation effect
Most preferably, according to the pump light of pumping source output in the mode-locking device M0In spot radius, each curved mirror focal length with
And the tilt angle and use propagation circle graphing method of the curved mirror decide the position of each curved mirror, obtain most
Good astigmatic compensation effect；In addition, by the way that thermal lens F is arranged in the passive mode-locking resonant cavityt, and the thermal lens Ftπ
The round and output plane mirror MoutIt is tangent, so that the output plane mirror MoutThe hot spot of preceding light beam changes minimum, light beam
Propagation characteristic is stablized.
Fig. 1 to Fig. 2 is please referred to, further, the curved mirror includes and the mode-locking device M0Between distance be L1
First surface reflecting mirror M1, the mode-locking device M0The beam waist parameter at place:
Wherein, ω0For the radius of the hot spot, λ is the wavelength of the hot spot；
The parameter b with a tight waist of side focus is calculated using formula (1)0；
It crosses the side focus and is tangential on the first surface reflecting mirror M with optical axis1Draw circle π1, the radius of the circle is described
First surface reflecting mirror M1The spot size at place；
Cross the side focus and with the first surface reflecting mirror M1Front surface tangent picture circle, the radius of the circle is described
First surface reflecting mirror M1Locate wave-front curvature radius.
The passive mode-locking resonant cavity utilizes and is incident to the mode-locking device M0The spot radius and hot spot wavelength of middle light beam
Calculate the mode-locking device M0Parameter with a tight waist, and according to the first surface reflecting mirror M1With the mode-locking device M0Between
Distance, using propagate circle graphing method can accurately determine the first surface reflecting mirror M1Position and according to made
Circle calculate the first surface reflecting mirror M1Wave-front curvature radius, implementation method is simple.
In this embodiment, son is illustrated as an example: as the spot radius ω of light beam0=40 μm, wavelength is
1064nm can calculate parameter b with a tight waist by formula (1)0=4.72mm, so as to the mode-locking device M0Position make
Circle, and according to the first surface reflecting mirror M1With mode-locking device M0The distance between L1=53mm, can determine that described first is bent
Face reflecting mirror M1Position, and have ever made side focus and the first surface reflecting mirror M1The tangent circle of front surface, made circle
Radius be the first surface reflecting mirror M1The wave-front curvature radius at place.
Referring to Fig.1 and 2, further, the first surface reflecting mirror M1Focal length be f1And inclination angle is θ1,
The first surface reflecting mirror M is calculated by following formula1In the focal length f of its meridian plane and sagittal surfacetAnd fs:
ft=f*cos θ (2)
Wherein, f is the focal length of the curved mirror, and θ is the inclination angle of the curved mirror；
And according to the relationship of radius of curvature after wavefront wave:
Wherein, R is wave-front curvature radius, and R ' is radius of curvature after wave；Described is calculated by formula (2), (3) and (4)
One curved reflector M1Wave after the radius R of radius of curvature and its meridian plane and sagittal surfacet' and Rs', respectively with the meridian plane
With the radius R of the sagittal surfacet' and Rs' it is diameter and the center of circle in optical axis upper drawing circle, and the circle and the first surface reflecting mirror
M1Rear surface it is tangent, the circle and the round π1Intersection point be the meridian plane and sagittal surface side focus F1tAnd F1s；
According to side focus F1tAnd F1sParameter b with a tight waist1tAnd b1s, aforesaid operations are repeated, the (n-1)th curved reflector M is obtainedn-1
Parameter b with a tight waist(n-1)tAnd b(n-1)s；Thereby determine that the second curved reflector M2To the (n-1)th curved reflector Mn-1Position
It sets, wherein n is the positive integer greater than 2.
The passive mode-locking resonant cavity utilizes the first surface reflecting mirror M1Focal length f1And tiltangleθ1, calculate described
First surface reflecting mirror M1Meridian plane and sagittal surface focal length ftAnd fs:, and utilize the first surface reflecting mirror M1Wavefront and
The relationship of radius of curvature can calculate the first surface reflecting mirror M after wave1Wave after radius of curvature and its meridian plane and arc
The radius R of sagittal planet' and Rs', respectively with the radius R of meridian plane described in this and the sagittal surfacet' and Rs' it is that diameter and the center of circle exist
Optical axis upper drawing circle, and the circle and the first surface reflecting mirror M1Rear surface it is tangent, the circle and the round π1Intersection point be institute
State the side focus F of meridian plane and sagittal surface1tAnd F1s, according to side focus F1tAnd F1sParameter b with a tight waist1tAnd b1s, thus repeat, it can
With the second curved reflector M of the determination curved mirror2, third curved reflector M3... ..., (n-1)th camber reflection
Mirror Mn-1Position.
Referring to Fig.1 and 2, further, the excessively described (n-1)th curved reflector Mn-1Side focus F(n-1)tAnd F(n-1)s
And justify π with the tangent picture of the optical axisn, in circle πnWith the n-th curved reflector M of placement at the point of contact of the optical axisn, described n-th is bent
Face reflecting mirror MnThe spot size of the light beam of the meridian plane and sagittal surface at place is identical, and the n-th curved reflector MnThe son of image space
The coincidence with a tight waist in noon face and sagittal surface, wherein n is the positive integer greater than 2.The n-th curved reflector MnThe meridian plane at place and
The spot size of the light beam of the sagittal surface is identical, the n-th curved reflector MnAstigmatism afterwards is fully compensated for, and described
N-th curved reflector MnPlace's meridian plane and the with a tight waist of sagittal surface are completely coincident.The passive mode-locking resonant cavity is mapped using circle is propagated
Method is mapped, and according to the (n-1)th curved reflector Mn-1Side focus F(n-1)tAnd F(n-1)sMake πnCircle, in circle πnWith
The n-th curved reflector M is placed at the point of contact of the optical axisn, so that it is determined that n-th curved reflector MnPosition.
Fig. 1 to Fig. 4 is please referred to, further, in the n-th curved reflector MnAfter the meridian plane at place and the wave of sagittal surface
Radius of curvature RtAnd RsIt is identical, it can be obtained according to formula (2) (3) (4) synthesis:
Wherein, fnFor the focal length of the n-th camber reflection lens, θnFor the inclination angle of the n-th camber reflection lens, n is greater than 2
Positive integer.
, according to formula (1), (2), (3) and (4), data are brought into respective formula with Fig. 3 as n=3 referring to figure 2.
It can obtain, Rt'=676.8842mm, Rs'=920.6766mm, then respectively with Rt' and Rs' be diameter draw circle, the center of circle on optical axis,
And with the second curved reflector M2Rear surface is tangent, round and the second curved reflector M2The intersection point for locating π circle is meridian plane sagittal surface
Side focus.Meanwhile crossing the second curved reflector M2Meridian plane and sagitta of arc surface side focus, and with optical axis is tangent to draw
One circle places third curved reflector M at point of contact3, this circle is third curved reflector M3The π circle at place, can thus protect
Meridian plane sagittal surface light beam is demonstrate,proved in third curved reflector M3It is identical to locate spot size, the second curved reflector M can be obtained through measurement2
With third curved reflector M3Distance L2=780.1787mm, cross side focus and with third curved reflector M3Front surface is tangent can
A circle (being not drawn into figure) is drawn, this circular diameter is equal to third curved reflector M3Wave-front curvature radius, through the known to measurement
Three curved reflector M3Locate wavefront radius of meridional section Rt=716.5283mm, sagittal surface radius of curvature Rs=856.2399mm.
It is compensated to the astigmatism after third curved reflector M3, it is necessary to make third curved reflector M3Virgin's noon sagitta of arc surface wave.
Radius of curvature is identical afterwards, according to formula (5), gives f3=300mm can obtain θ3=14.891 °.Further according to formula (4)
Third curved reflector M can be acquired3Radius of curvature is 486.9476mm after wave, then it is anti-to draw third curved surface with 486.9476 for diameter
Penetrate mirror M3Circle after wave, with π3Circle intersection point be image side focus, then image space beam waist position it is also known that, through measurement known to third
Curved reflector M3With output plane mirror MoutDistance be L3=397.9326mm.It is flat that output is placed at image space beam waist position
Face mirror Mout, then upper figure is formed a both arms astigmatic compensation cavity.
Referring to figure 4., further, the σ circle and the thermal lens F of the flat output mirrortThe π circle at place is tangent and tangent
Point is located at the n-th curved reflector MnImage side focal point.
In this embodiment, thermal lens FtWhen focal length variations, σoutCircle passes through thermal lens FtPicture σ 'outAnd σo"utIt is handed over π circle
Point is in FnNearby move back and forth, in the case where thermal agitation is little, FnMovement be almost negligible, therefore thermal lens Ft
The optical parameter variation in left side is also negligible.
Further, the thermal lens FtMake thin lens processing.
Referring to figure 4., for example, the passive mode-locking resonant cavity is to include single thermal lens Ft(representing laser crystal)
Laser cavity, by thermal lens FtMake thin lens processing.First surface reflecting mirror M1The corrugated at place can be indicated with the circle of σ 1, make the t1 of the circle of σ 1
Circle, it is tangent with the circle of σ 1.When thermal lens Ft focal length is f0,1 circle transformation of σ is the circle of σ 1 ', according to the transformation rule of transform circle, σ
1 ' fenestra and t1 circle are tangent.When thermal lens Ft focal length fluctuations, 1 ' fenestra of σ can change, but the circle of σ 1 ' is always to maintain
The tangent relationship with t1 circle, point of contact is moved about in Fl1 '.In the case where focal length variations are little, mobile point of contact is also very little
, it is almost negligible.Therefore, we select the second curved reflector M appropriate2, only require its circle of σ 2 by cutting
Point Fl1 ', so that it may make the second curved reflector M2Gaussian beam variation in one side is minimum.It means that in this cavity configuration, the
Two curved reflector M2The propagation characteristic of the Gaussian beam on one side is sufficiently stable.
It is illustrated below with an example:
Referring to figure 3. and Fig. 4, according to curved mirror method for determining position each in astigmatic compensation unit, we can be designed
Both arms astigmatic compensation chamber in dotted line frame out, and the 4th toroidal lens M can be measured4Locate the size of parameter b4 with a tight waist, b4
=188.2073mm, in M5Locate holding plane outgoing mirror；According to the σ of flat output mirror circle and the thermal lens FtThe π circle at place
It is tangent, when thermal lens Ft focal length disturbs, as long as M5With thermal lens FtOn π circle it is tangent, b4 variation can be made minimum, then mode locking
Device M0On parameter b1 with a tight waist variation it is also minimum.It can be measured using asymmetric flat chamber neutrality Condition Method in pumping electricity
Thermal lens F when stream is 9AtFocal length is ft=800mm, wave-front curvature radius at thermal lens Ft are as follows:
Due to flat output mirror M5It is tangential on π at ft and justifies the rightmost side, therefore, radius of curvature and thermal lens after thermal lens Ft wave
Ft π circular diameter is equal, i.e., are as follows:
It is obtained by formula (4):
It calculates, the 4th curved reflector M4Focal length ft=-124.5416mm, then third curved reflector M3Focal length
Ft=273.391mm, third curved reflector M3The distance between flat output mirror L3=135.3098mm.
Finally, we obtain each parameter of resonant cavity are as follows: first surface reflecting mirror M1With the second curved reflector M2Between away from
From L1=53mm, the second curved reflector M2With third curved reflector M3The distance between L2=780.1787mm, third curved surface
Reflecting mirror M3Focal length ft=273.391mm, third curved reflector M3With output plane mirror MoutThe distance between L3=
135.3098mm the second curved reflector M2Inclination angle be 8 °, third curved reflector M3Inclination angle be 14.891 °.
Mode locking experiment is carried out to the passive mode-locking resonant cavity in above-described embodiment.
The high speed digital oscilloscope (DPO4104B, Tektronix, Inc, USA) of 1HHz bandwidth and high speed are utilized in experiment
Photodetector (PIN2-11-12, Hi-Teck Optoclectronics Co.Ltd, China) observes mode locking pulse
And Output optical power is measured using power meter (30A-P-17, Optronics Solutions Ltd, Israel).
Fig. 5 gives mode locking of the common chamber optimization chamber under room temperature (20 DEG C of water temperature) as a result, Fig. 5 is 20 DEG C of output pulse sequences of water temperature,
Wherein, Fig. 5 (a) and Fig. 5 (b) optimizes chamber output pulse sequence, Fig. 5 (c) and the common chamber output pulse sequence of Fig. 5 (d).From Fig. 5
In it can be seen that two kinds of lumen type at room temperature can be stable mode locking.
In order to analyze two kinds of lumen type thermal stability, our artificial adjustment water cooling box water temperatures carry out pair to 15 DEG C and 25 DEG C
Than, as shown in fig. 6, it gives 25 DEG C of output pulse sequences of 15 DEG C of output pulse sequences of left side water temperature and the right water temperature,
Middle Fig. 6 (a) and Fig. 6 (b) optimization chamber output；The common chamber output of Fig. 6 (c) and Fig. 6 (d).15 DEG C and 25 DEG C optimization as seen from Figure 6
Chamber still can continue to keep stable mode locking, and the mode locking waveform of common chamber gets muddled, sometimes even losing lock.
Different pumping current near fields far field output facula quality is measured, as a result as shown in 7.Fig. 7 indicates room
Influence of the different pumping currents to output facula under warm (20 DEG C), the as can be seen from Figure 7 increase of pumping current, common chamber
Output facula quality is deteriorated (astigmatism is increasing), and optimizes chamber output facula substantially unchanged (astigmatism obtains always preferably
Compensation), this just illustrates that optimizing chamber astigmatism under thermal agitation is always compensated, and the beam quality of common chamber can be deteriorated.It is real
Result is tested to meet with theory analysis.
Influence of the water temperature to two kinds of lumen type output powers is as shown in 8.Fig. 8 shows different water temperatures to two kinds of lumen type output works
The influence of rate, wherein abscissa indicates pumping current, and 15 DEG C~25 DEG C of water temperature was every once measuring an output work under each electric current
Rate, then acquires the standard deviation and average value of 11 output powers, and ordinate indicates that the opposite variation of output power is standard deviation
Divided by average value.As can be seen from Figure 8 changing for water temperature can't make a big impact to the output power of optimization chamber, fluctuate
Very little, and for common chamber, the variation of water temperature causes output power to change tens milliwatts even milliwatts up to a hundred, influences huge
Greatly.In electric current 10A, water temperature influences the output power of optimization chamber minimum, is consistent with our theoretical analysis results.
The steadiness of two kinds of lumen type output powers is as shown in Figure 9 under different water temperatures.Fig. 9 indicates under three kinds of water temperatures two kinds
The stability of lumen type output power, wherein abscissa indicates pumping current, we read primary every one minute under each electric current
Output power, totally 50 times, ordinate indicates variation of the standard deviation relative to average value of this 50 output powers.It can from Fig. 9
To find out, the output-power fluctuation fluctuating for optimizing chamber under three kinds of water temperatures is smaller, and minimum is fluctuated at 20 DEG C (red dotted line), this
Be since our thermal lens Ft measurements are completed at 20 DEG C, theoretically optimize chamber be also exported at 20 DEG C it is most stable, because
This theory is consistent with experiment.
In experiment optimize chamber each parameter we be according to thermal lens Ft focus design under pumping current 10A, therefore, electricity
Influence of the water temperature to two kinds of lumen type output powers is as shown in Figure 10 when flowing 10A.Figure 10 indicates that water temperature is to output under pumping current 10A
The influence of power, wherein abscissa indicates water temperature, every the output power of readings in one minute under each water temperature, totally 50 times, indulges seat
Mark indicates variation of the standard deviation of 50 output powers relative to mean power.As can be seen from Figure 10 the different water at 10A
Influence of the temperature to optimization chamber output power can be ignored, this is consistent with theory analysis substantially close to 0.The present invention also mentions
A kind of laser, including above-mentioned passive mode-locking resonant cavity are supplied.Passive mode-locking resonant cavity in the embodiment has above-mentioned each reality
The identical design feature of passive mode-locking resonant cavity in example is applied, role is identical, does not repeat this time.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all in essence of the invention
Made any modifications, equivalent replacements, and improvements etc., should all be included in the protection scope of the present invention within mind and principle.
Claims (8)
1. a kind of passive mode-locking resonant cavity, which is characterized in that the resonant cavity be both arms astigmatic compensation chamber, and including pumping source,
The mode-locking device and output plane mirror that are set in the end walls of the both arms astigmatic compensation chamber, at least one be set to the lock
Astigmatic compensation unit in optical path between mold part and the output plane mirror and be set to the mode-locking device with it is described
Between output plane mirror and its π justifies and the tangent thermal lens of the output plane mirror；Each astigmatic compensation unit includes at least
Two curved mirrors, the meridian plane on the curved mirror of the output plane mirror are identical with the spot size of sagittal surface；Institute
It is ω that the pump light for stating pumping source output, which is incident in the mode-locking device and generates radius in the mode-locking device,0Light
Spot passes through biography according to the inclination angle of the spot radius size, the focal length of each curved mirror and at least one curved mirror
Broadcast the position that round graphing method determines each curved mirror.
2. passive mode-locking resonant cavity as described in claim 1, which is characterized in that the curved mirror includes and the mode-locking device
Between distance be L1 first surface reflecting mirror, the beam waist parameter at the mode-locking device:
Wherein, ω0For the radius of the hot spot, λ is the wavelength of the hot spot；
The parameter b with a tight waist of side focus is calculated using formula (1)0；
It crosses the side focus and is tangential on the first surface reflection mirror drawing circle π with optical axis1, the radius of the circle is described first bent
Spot size at the reflecting mirror of face；
It crosses the side focus and justifies with the tangent picture of the front surface of the first surface reflecting mirror, the radius of the circle is described first bent
Wave-front curvature radius at the reflecting mirror of face.
3. passive mode-locking resonant cavity as claimed in claim 2, which is characterized in that the focal length of the first surface reflecting mirror is f1
And inclination angle is θ1, the first surface reflecting mirror is calculated in the focal length f of its meridian plane and sagittal surface by following formulatAnd fs:
ft=f*cos θ (2)
Wherein, f is the focal length of the curved mirror, and θ is the inclination angle of the curved mirror；
And according to the relationship of radius of curvature after wavefront wave:
Wherein, R is wave-front curvature radius, and R ' is radius of curvature after wave；It is bent that described first is calculated by formula (2), (3) and (4)
The radius R of radius of curvature and its meridian plane and sagittal surface after the wave of face reflecting mirrort' and Rs', respectively with the meridian plane and described
The radius R of sagittal surfacet' and Rs' it is diameter and the center of circle in optical axis upper drawing circle, and the rear table of the circle and the first surface reflecting mirror
Face is tangent, the circle and the round π1Intersection point be the meridian plane and sagittal surface side focus F1tAnd F1s；
According to side focus F1tAnd F1sParameter b with a tight waist1tAnd b1s, aforesaid operations are repeated, the with a tight waist of the (n-1)th curved reflector is obtained
Parameter b(n-1)tAnd b(n-1)s；Thereby determine that the second curved reflector to the position of (n-1)th curved reflector, wherein n is big
In 2 positive integer.
4. passive mode-locking resonant cavity as claimed in claim 3, which is characterized in that the side of excessively described (n-1)th curved reflector is burnt
Point F(n-1)tAnd F(n-1)sAnd justify π with the tangent picture of the optical axisn, in circle πnWith the n-th camber reflection of placement at the point of contact of the optical axis
Mirror, the meridian plane at n-th curved reflector is identical with the spot size of the light beam of sagittal surface, and n-th camber reflection
The coincidence with a tight waist of the meridian plane and sagittal surface of mirror image side, wherein n is the positive integer greater than 2.
5. passive mode-locking resonant cavity as claimed in claim 4, which is characterized in that the meridian at n-th curved reflector
Radius of curvature R after the wave of face and sagittal surfacetAnd RsIt is identical, it can be obtained according to formula (2) (3) (4) synthesis:
Wherein, fnFor the focal length of the n-th camber reflection lens, θnFor the inclination angle of the n-th camber reflection lens, n is just whole greater than 2
Number.
6. passive mode-locking resonant cavity as claimed in claim 4, which is characterized in that σ circle and the heat of the flat output mirror
The tangent and points of tangency of π circle at lens is located at the image side focal point of n-th curved reflector.
7. the passive mode-locking resonant cavity as described in claim 1 to 6 any one, which is characterized in that the thermal lens is made thin
Mirror processing.
8. a kind of laser, which is characterized in that including passive mode-locking resonant cavity as claimed in any one of claims 1 to 7.
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| CN113391319A (en) * | 2021-06-11 | 2021-09-14 | 森思泰克河北科技有限公司 | Manufacturing method of laser radar shell and laser radar shell |
| CN113391319B (en) * | 2021-06-11 | 2022-07-29 | 森思泰克河北科技有限公司 | Manufacturing method of laser radar shell and laser radar shell |
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