CN101609959B - Littrow structure raster outer cavity semiconductor laser device and quasi-synchronization tuning method - Google Patents
Littrow structure raster outer cavity semiconductor laser device and quasi-synchronization tuning method Download PDFInfo
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Abstract
本发明公开一种利特罗(Littrow)结构光栅外腔半导体激光器和准同步调谐方法，在半导体激光器中，半导体激光管发出的光经准直透镜准直后入射到光栅，其中，θ为半导体激光管发出的光经准直透镜准直后在光栅上的入射角或衍射角，xq为光栅调谐转动中心到等效外腔半导体激光器反射面的距离，uq为光栅调谐转动中心到光栅衍射表面所在平面的距离；如果从半导体激光管发出到光栅的光线与调谐转动中心位于所述等效外腔半导体激光器反射面的同侧，则xq为正，反之为负，如果从半导体激光管发出到光栅的光线与调谐转动中心位于在光栅表面所在平面的同侧，则uq为正，反之为负。本发明更易于设计实现激光的同步转动频率或波长调谐。
The invention discloses a Littrow structure grating external cavity semiconductor laser and a quasi-synchronous tuning method. In the semiconductor laser, the light emitted by the semiconductor laser tube is collimated by a collimator lens and then incident on the grating, where θ is the semiconductor The incident angle or diffraction angle of the light emitted by the laser tube on the grating after being collimated by the collimating lens, xq is the distance from the grating tuning rotation center to the reflection surface of the equivalent external cavity semiconductor laser, and uq is the grating tuning rotation center to the grating diffraction surface The distance of the plane where it is located; if the light emitted from the semiconductor laser tube to the grating is on the same side as the tuning rotation center of the equivalent external cavity semiconductor laser reflective surface, then xq is positive, otherwise it is negative, if it is sent from the semiconductor laser tube to If the light of the grating is on the same side as the tuning rotation center on the plane where the grating surface is located, then uq is positive, otherwise it is negative. The invention is easier to design and realize the synchronous rotation frequency or wavelength tuning of the laser.
Description
Technical field
The present invention relates to the grating-feedback extended-cavity diode laser tunable technology, refer to especially the quasi-synchronous tuning method of a kind of Littrow (Littrow) structure fringe external-cavity semiconductor laser.
Background technology
Littrow structure external-cavity semiconductor laser comprises as shown in Figure 1: semiconductor laser tube (LD) 1, aspheric collimation lens (AL) 3, grating (GT) 12.In the Littrow structure, the laser that semiconductor laser tube 1 is sent is incident on the diffraction grating 12 behind aspheric collimation lens 3 collimations.First-order diffraction light and the incident light conllinear of grating 12 oppositely turn back in the semiconductor laser tube 1 along former road.
Among Fig. 1, N represents the grating normal, θ represents that light beam is the incidence angle on the grating 12 and the angle of diffraction (incidence angle that incides on the grating 12 of laser equals the angle of diffraction) here, P represents the arbitrarily tuning center of rotation of grating, and P0 represents to satisfy the tuning center of rotation of the routine of the tuning condition of grating synchronizing frequency.SL represents equivalent external-cavity semiconductor laser reflecting surface SL, be and the plane of being sent by semiconductor laser tube 1 and light behind collimating lens 3 collimation is vertical, it equals the optical cavity length l of grating external cavity semiconductor laser apart from the distance of the intersection point Q of this light center line and grating 12 Difraction surfaces; SG represents the plane, Difraction surface place of grating 12.Planar S L, SG are vertical with the light path face.For convenience of description, set up coordinate system xOy at the light path face, the x axle is the light center line that semiconductor laser tube 1 is sent, and the y axle is the intersection of planar S L and light path face, and origin of coordinates O is the center line of laser beam and the intersection point of planar S L.Can find out, origin of coordinates O is exactly described optical cavity length l to the distance of the Difraction surface intersection point Q of described light center line and grating 12, owing to factor affecting such as the gain media that is subjected to semiconductor laser tube 1 and collimating lens 3 refractive indexes, this optical cavity length l compares slightly long with the actual range that semiconductor laser tube 1 is ordered to described Q.The tuning center of rotation of supposing current grating 12 is P (x, y), x be the tuning center of rotation P of grating to the distance on SL plane, u is that the tuning center of rotation P of grating is to the distance on SG plane.The parameter x of expression grating tuning center position and the sign convention of u are among Fig. 1: if the with it light of effect and the homonymy of tuning center of rotation on the plane then for just, otherwise are to bear.Can find out that according to above-mentioned rule x is for just in Fig. 1, u is for negative.The rotation axis of grating 12 (being tuning center of rotation P place straight line) is perpendicular to the light path face, and is namely vertical with the xOy plane.
In the Littrow structure, the tuning of optical maser wavelength or frequency is by rotation diffraction grating 12, and the incident of 12 pairs of light of change grating and the angle of diffraction realize.Yet in the process of rotating shutter 12, the frequency-selecting effect of the F-P exocoel that consists of between the frequency-selecting effect of grating 12 and grating 12 and the laser tube 1 equivalent rear surface SL is changed simultaneously.Generally speaking, above-mentioned change is not synchronous, thereby will cause the mode hopping of zlasing mode, has interrupted the continuous tuning of laser frequency so that available laser frequency the mode hopping continuous tuning coverage is very not little, 1 to 2 GHz for example.In order to realize the simultaneous tuning on a large scale of wavelength or frequency, namely desirable not mode hopping cline frequency is tuning, generally need to make the tuning center of rotation P of grating 12 be taken at the P0 point, and wherein P0 (x0, u0) satisfies two conditions simultaneously:
x0＝0 (1)
u0＝0 (2)
Above equation group represents that the simultaneous tuning center of rotation is positioned at the intersection point of two straight lines of SL, SG and xy Plane intersects.If the optical cavity length l of grating external-cavity laser determines that above-mentioned two constraintss also can be expressed as in quadrature (x, y) plane:
x0＝0 (3)
y0＝l/tan(θ) (4)
In order to realize the simultaneous tuning on a large scale of wavelength or frequency, Littrow structure external-cavity semiconductor laser must guarantee that above-mentioned (1) and (2) or (3) and (4) two constraintss are satisfied simultaneously on structural design.The position of satisfying this pair of constraints only is a bit on x and the y plane, in actual laser, accurately finds this point to need 2 governor motions with independence and freedom degree.This restriction has caused the complexity of mechanical structure and has increased destabilizing factor.Particularly the position P0 (x0, u0) of tuning center of rotation can not leave planar S G and the equivalent external-cavity semiconductor laser reflecting surface SL at grating 12 surperficial places, and this is very inconvenient for many application.
Summary of the invention
In view of this, the present invention proposes a kind of quasi-synchronous tuning method of Littrow structure fringe external-cavity semiconductor laser, is easy to design frequency or the wavelength tuning of realizing that laser synchronization rotates.
Quasi-synchronous tuning method based on above-mentioned purpose Littrow structure fringe provided by the invention external-cavity semiconductor laser, in described semiconductor laser, the light that semiconductor laser tube is sent incides grating behind the collimating lens collimation, the light path face of the light that the rotation axis of described grating sends perpendicular to semiconductor laser tube, carrying out the output frequency of laser when tuning by rotating described grating, make the position (xq, yq) of tuning center of rotation in coordinate system xOy of grating satisfy relational expression: xq+uq/cos θ=0;
Wherein, coordinate system xOy builds on the light path face, x axle among the coordinate system xOy is the light center line that semiconductor laser tube is sent, y axle among the coordinate system xOy is the intersection of equivalent external-cavity semiconductor laser reflecting surface and light path face, origin of coordinates O is the center line of laser beam and the intersection point of equivalent external-cavity semiconductor laser reflecting surface, θ is light incidence angle or angle of diffraction on grating behind the collimating lens collimation that semiconductor laser tube is sent, xq is the distance that the tuning center of rotation of grating arrives equivalent external-cavity semiconductor laser reflecting surface, and uq is that the tuning center of rotation of grating is to the distance on plane, place, optical grating diffraction surface; If be issued to the light of grating and the homonymy that tuning center of rotation is positioned at described equivalent external-cavity semiconductor laser reflecting surface from semiconductor laser tube, then xq is for just, otherwise for negative, if be issued to the light of grating and the homonymy that tuning center of rotation is located at plane, grating surface place from semiconductor laser tube, then uq is being for just, otherwise for negative; Equivalence external-cavity semiconductor laser reflecting surface is and the plane of being sent by semiconductor laser tube and light behind the collimating lens collimation is vertical, the distance of the center line of the light that it sends apart from semiconductor laser tube and grating diffration surface intersection point equals the optical cavity length l of grating external cavity semiconductor laser.
Better, if the optical cavity length l of described grating external cavity semiconductor laser determines in the method, then carrying out the output frequency of laser when tuning by rotating described grating, make the position (xq of the tuning center of rotation of grating, yq) be positioned on the straight line of satisfied relational expression yq=l/tan (θ), wherein, the distance of the yq beam center line of light behind the collimating lens collimation that to be tuning center of rotation send to semiconductor laser tube.
Better, the method is passed through to make the position of the tuning center of rotation of grating of semiconductor laser satisfy described relational expression xq+uq/cos θ=0 or yq=l/tan (θ) in the position of the tuning center of rotation of a described grating of above degree of freedom adjusted.
Better, the method arranges the tuning center of rotation governor motion of grating of one degree of freedom in described semiconductor laser, this governor motion can make the tuning center of rotation arrival of grating satisfy at least one point of corresponding relation formula xq+uq/cos θ=0 or yq=l/tan (θ); And grating is set rotates governor motion grating is rotated take described tuning center of rotation place straight line as axle, described tuning center of rotation place straight line is perpendicular to coordinate system xOy plane;
By the tuning center of rotation governor motion of described grating, make the tuning center of rotation of grating on the described degree of freedom to a direction displacement;
Regulate the continuous adjustable range of frequency that grating rotates governor motion and detects the semiconductor laser Output of laser, judge that whether the continuous adjustable range of this frequency increases with the change of the tuning center position of grating, if, then make the tuning center of rotation of grating continue in the direction displacement, until the continuous adjustable range of Output of laser frequency satisfies the demand of using; Otherwise, along with the tuning center of rotation of the described grating of rightabout displacement of current direction of displacement, until the continuous adjustable range of Output of laser frequency satisfies the demand of using.
Based on above-mentioned purpose, the present invention also provides a kind of Littrow Littrow structure fringe external-cavity semiconductor laser, comprising: the light that semiconductor laser tube, collimating lens and grating, semiconductor laser tube send incides grating behind the collimating lens collimation, also comprise:
The tuning center of rotation governor motion of grating, the tuning center of rotation that is used for regulating grating makes the position (xq, yq) of tuning center of rotation in coordinate system xOy of grating satisfy relational expression: xq+uq/cos θ=0;
Wherein, coordinate system xOy builds on the light path face, x axle among the coordinate system xOy is the light center line that semiconductor laser tube is sent, y axle among the coordinate system xOy is the intersection of equivalent external-cavity semiconductor laser reflecting surface and light path face, origin of coordinates O is the center line of laser beam and the intersection point of equivalent external-cavity semiconductor laser reflecting surface, θ is light incidence angle or angle of diffraction on grating behind the collimating lens collimation that semiconductor laser tube is sent, xq is the distance that the tuning center of rotation of grating arrives equivalent external-cavity semiconductor laser reflecting surface, and uq is that the tuning center of rotation of grating is to the distance on plane, place, optical grating diffraction surface; If be issued to the light of grating and the homonymy that tuning center of rotation is positioned at described equivalent external-cavity semiconductor laser reflecting surface from semiconductor laser tube, then xq is for just, otherwise for negative, if be issued to the light of grating and the homonymy that tuning center of rotation is located at plane, grating surface place from semiconductor laser tube, then uq is being for just, otherwise for negative; Equivalence external-cavity semiconductor laser reflecting surface is and the plane of being sent by semiconductor laser tube and light behind the collimating lens collimation is vertical, the distance of the center line of the light that it sends apart from semiconductor laser tube and grating diffration surface intersection point equals the optical cavity length l of grating external cavity semiconductor laser;
And grating rotates governor motion, and grating is rotated take described tuning center of rotation place straight line as axle, and described tuning center of rotation place straight line is perpendicular to coordinate system xOy plane, the light path face of the light that the rotation axis of described grating sends perpendicular to semiconductor laser tube.
Better, the optical cavity length l of this grating external cavity semiconductor laser is for determining yardstick; The tuning center of rotation governor motion of described grating, make the position (xq of the tuning center of rotation of grating, yq) be positioned on the straight line of satisfied relational expression yq=l/tan (θ), wherein, the distance of the yq beam center line of light behind the collimating lens collimation that to be tuning center of rotation send to semiconductor laser tube.
Better, the tuning center of rotation governor motion of the described grating of this semiconductor laser is in the position of the tuning center of rotation of a described grating of above degree of freedom adjusted.
Better, the tuning center of rotation governor motion of the described grating of this semiconductor laser, make the tuning center of rotation of grating on one degree of freedom to a direction displacement; Regulate the continuous adjustable range of frequency that grating rotates governor motion and detects the semiconductor laser Output of laser, judge that whether the continuous adjustable range of this frequency increases with the change of the tuning center position of grating, if, then regulate the tuning center of rotation governor motion of described grating and make the tuning center of rotation of grating continue in the direction displacement, until the continuous adjustable range of Output of laser frequency satisfies the demand of using; Otherwise, regulate the tuning center of rotation governor motion of described grating, along with the tuning center of rotation of the described grating of rightabout displacement of current direction of displacement, until the continuous adjustable range of Output of laser frequency satisfies the demand of using.
Better, the tuning center of rotation governor motion of the described grating of this semiconductor laser is the tuning center of rotation micrometer adjusting screw of grating, it is the laser frequency tuning micrometer adjusting screw that grating rotates governor motion, and this semiconductor laser also comprises: the grating adjusting bracket moves plate, the grating adjusting bracket is decided plate, grating adjusting bracket piezoelectric ceramic and grating fixing bracket;
Grating is fixed on the moving plate of described grating adjusting bracket by grating fixing bracket, the tuning center of rotation micrometer adjusting screw of laser frequency tuning micrometer adjusting screw and grating is arranged on described grating adjusting bracket to be decided on the plate, and the tuning center of rotation of grating is positioned on the central axis of the tuning center of rotation micrometer adjusting screw of grating; Move by regulating the moving plate of the tuning center of rotation micrometer adjusting screw drive of grating grating adjusting bracket, make the tuning center of rotation of grating arrive the position of satisfying relational expression xq+uq/cos θ=0 or yq=l/tan (θ), drive the moving plate of grating adjusting bracket by regulating the laser frequency tuning micrometer adjusting screw, the grating on it is rotated around the tuning center of rotation of described grating.
Better, this semiconductor laser further arranges grating adjusting bracket piezoelectric ceramic and is used for minor adjustments is done in the rotation of the moving plate of grating adjusting bracket between the moving plate of described grating adjusting bracket and laser frequency tuning micrometer adjusting screw.
Can find out from above, the quasi-synchronous tuning method of Littrow structure fringe external-cavity semiconductor laser provided by the invention, reduced the constraints number, two constraintss are reduced to one, so that the position of satisfying the tuning constraints of mode hopping cline frequency is not regulated the degree of freedom by a bit being extended to straight line on x and the y plane thereby only need one on the governor motion.Remove the position of tuning center of rotation and can not leave the planar S G at place, optical grating diffraction surface and the restriction of equivalent external-cavity semiconductor laser reflecting surface SL.So that simultaneous tuning has more selection and larger performance leeway and space.Be easy to design synchronous rotating dynamic frequency or the wavelength tuning of realizing laser, and so that structure is more stable and simple, be more prone to adjust.
Description of drawings
Fig. 1 is the structural representation of Littrow structure external-cavity semiconductor laser;
Fig. 2 is the structural representation of quasi-synchronous tuning Littrow structure external-cavity semiconductor laser embodiment of the present invention;
Fig. 3 is that the present invention is with the quasi-synchronous tuning Littrow structure external-cavity semiconductor laser embodiment schematic diagram of regulating parts.
Embodiment
With reference to the accompanying drawings the present invention is described more fully, exemplary embodiment of the present invention wherein is described.
The present invention proposes to adopt quasi-synchronous tuning method to realize the continuous tuning of laser frequency, and it has comprised conventional simultaneous tuning condition interior.The external-cavity semiconductor laser of quasi-synchronous tuning Littrow structure comprises referring to shown in Figure 2 in the embodiment of the invention: semiconductor laser tube 1, collimating lens 3, diffraction grating 12.The laser that semiconductor laser tube 1 is sent is incident on the diffraction grating 12 behind aspheric collimation lens 3 collimations.First-order diffraction light and the incident light conllinear of grating 12 oppositely turn back in the semiconductor laser tube 1 along former road.
Among Fig. 2, N represents the grating normal, θ represent light beam on grating 12 incidence angle and the angle of diffraction (for the Littrow structure, the incidence angle that laser incides on the grating 12 equals the angle of diffraction), P represents the arbitrarily tuning center of rotation of grating, and P0 represents to satisfy the tuning center of rotation of the routine of the tuning condition of grating 12 synchronizing frequencies.SL represents equivalent external-cavity semiconductor laser reflecting surface, it is and the plane of being sent by semiconductor laser tube 1 and light behind collimating lens 3 collimation is vertical, the distance of the center line of the light that it sends apart from semiconductor laser tube 1 and the Difraction surface intersection point Q of grating 12 equals the optical cavity length l of grating external cavity semiconductor laser; SG represents the plane, Difraction surface place of grating 12.Planar S L, SG are vertical with the light path face.For convenience of description, set up coordinate system xOy at the light path face, the x axle is the light center line that semiconductor laser tube 1 is sent, and the y axle is the intersection of planar S L and light path face, and origin of coordinates O is the center line of laser beam and the intersection point of planar S L.Can find out, origin of coordinates O is exactly described optical cavity length l (owing to factor affecting such as the gain media that is subjected to semiconductor laser tube 1 and collimating lens 3 refractive indexes, this optical cavity length l compares slightly long with the actual range that semiconductor laser tube 1 is ordered to described Q) to the distance of the intersection point Q of described light center line and grating 12 Difraction surfaces.
Find according to long-term system research and great many of experiments, have the quasi-synchronous tuning center of rotation Pq (xq, uq) of diffraction grating 12, and this tuning center of rotation Pq satisfy following relationship:
xq×cosθ+uq＝0 (5)
Wherein, xq be grating quasi-synchronous tuning center of rotation Pq to the distance on SL plane, uq is grating quasi-synchronous tuning center of rotation Pq to the distance of planar S G.The sign convention of xq and uq is, if light and tuning center of rotation Pq at the homonymy of respective planes, then for just, on the contrary for negative.If namely be issued to the center line OQ of grating 12 light and the homonymy that tuning center of rotation Pq is positioned at planar S L from semiconductor laser tube 1, then xq is being for just, otherwise for negative; If be issued to the center line OQ of grating 12 light and the homonymy that tuning center of rotation Pq is positioned at grating 12 surperficial place planar S G from semiconductor laser tube 1, then uq is being for just, otherwise for negative.Can find out that according to above-mentioned rule in Fig. 2, for planar S L, light and tuning center of rotation Pq all are positioned at the SL right side, then xq is for just, and for planar S G, light and tuning center of rotation Pq lay respectively at the both sides of SG, and then uq is for negative.The rotation axis of grating 12 (being tuning center of rotation Pq place straight line) is perpendicular to the light path face, and is namely vertical with the xOy plane.
Draw by a large amount of experiments, when formula (5) is satisfied in the position of the tuning center of rotation Pq of grating 12, can obtain obviously to be better than the obvious larger not mode hopping cline frequency simultaneous tuning scope of other point, therefore the Pq that claims to meet the above-mentioned relation formula is the quasi-synchronous tuning center of rotation, Pq (xq, uq) more (satisfy formula (1), (2) near P0, or (3), (4)), cline frequency simultaneous tuning scope larger (the continuously adjustable scope is infinity in theory when reaching P0).In practice, the cline frequency simultaneous tuning scope of tens GHz or a hundreds of GHz can satisfy the demand of quite a lot of application.And ideally, semiconductor laser for conventional yardstick, that is to say (general semiconductor laser all meets this hypothesis) when x and u are not large especially, tuning center of rotation is positioned at Pq (xq, uq) time, the output light cline frequency simultaneous tuning scope of semiconductor laser can reach tens to GHz up to a hundred, even thousands of GHz, therefore can both satisfy most of application requirements.Give an example, in 100 millimeters, hundreds of millimeter even larger in some situation all is to obtain reasonable tuning effect to Pq to the distance of P0.
The present invention just can make the position of the tuning center of rotation Pq of grating satisfy described relational expression by in the position of the tuning center of rotation Pq of the described grating 12 of one degree of freedom adjusted like this, just can satisfy the overwhelming majority's application requirements.
If the optical cavity length l of Littrow structure fringe outside cavity gas laser is definite, then on the xOy plane, the track of the tuning center of rotation Pq coordinate of grating (xq, yq) of satisfy condition (5) is the straight line on the xOy plane, and this linear equation is:
yq＝l/tan(θ) (6)
Wherein, yq be quasi-synchronous tuning center of rotation Pq to the distance of x axle, the distance of the beam center line of light behind collimating lens 3 collimations that send to semiconductor laser tube 1 of quasi-synchronous tuning center of rotation Pq namely.Compare with (4) with condition (3), be equivalent to condition (3) and be removed, and only be left condition (4).
From laser actual physics space, the present invention can regard as, on the xOy coordinate plane, satisfy to realize the span of the coordinate Pq (xq, yq) of quasi-synchronous tuning, 1 the P0 (x0 that is limited by conventional simultaneous tuning condition institute (3) and (4), y0), be extended for the conventional simultaneous tuning fulcrum of a mistake P0 on (x, y) plane, comprise this point and with resonator in the straight line of light ray parallel.Not in the interval (conventional semiconductor laser yardstick) away from P0, can reach preferably simultaneous tuning effect on this straight line that the present invention recommends, this interval can be positioned at any side that P0 is ordered.On this straight line, can obtain obviously to be better than the obvious larger not mode hopping cline frequency simultaneous tuning scope of other point, and on this straight line near conventional simultaneous tuning point P0 (x0, y0), the simultaneous tuning scope is larger.
For realizing above-mentioned adjusting, in one embodiment of the present of invention, the tuning center of rotation governor motion of grating is set in described semiconductor laser, be used for regulating the tuning center of rotation Pq of grating, make the position of the tuning center of rotation Pq of grating satisfy relational expression (5) or under the long stable condition in chamber, satisfy relational expression (6); And grating is set rotates governor motion grating 12 is rotated take described tuning center of rotation Pq as axle.
By the tuning center of rotation governor motion of described grating, make the tuning center of rotation Pq of grating on one degree of freedom to a direction displacement (namely changing the position); When being displaced to certain position, regulate the continuous adjustable range of frequency that grating rotates governor motion and detects the semiconductor laser Output of laser, judge that whether the continuous adjustable range of this frequency increases with the change of the tuning center of rotation Pq of grating position, if, then regulate the tuning center of rotation governor motion of described grating, make the tuning center of rotation Pq of grating continue in the direction displacement, until the continuous adjustable range of Output of laser frequency satisfies the demand of using; Otherwise, regulate the tuning center of rotation governor motion of described grating so that the tuning center of rotation Pq of described grating along with the direction displacement of current displacement opposite direction, until the continuous adjustable range of Output of laser frequency satisfies the demand of using.
Certainly, the tuning center of rotation governor motion of described grating also can have one with the last degree of freedom, such as: when two degrees of freedom are arranged, can by in the one degree of freedom adjusted, the tuning center of rotation Pq of grating be adjusted to a bit that satisfies formula (5) or (6); By in another degree of freedom adjusted, the tuning center of rotation Pq of grating is approached or away from described P0 point.
Referring to shown in Figure 3, be the specific embodiment of the present invention with above-mentioned governor motion, comprise: semiconductor laser tube 1, semiconductor laser tube is heat sink 2, aspheric collimation lens 3, collimation mirror holder 4, base plate 5, the moving plate 6 of grating adjusting bracket, grating adjusting bracket are decided plate 7, laser frequency tuning micrometer adjusting screw 8, the tuning center of rotation micrometer adjusting screw 9 of grating, grating adjusting bracket piezoelectric ceramic 10, grating fixing bracket 11, diffraction grating 12.
Wherein N is the grating normal, θ is incidence angle and the angle of diffraction of light beam on grating 12, Pq represents the tuning center of rotation of the accurate synchronizing frequency of grating, SL represents plane, y axle place, it equals optical cavity length l apart from the distance of light center line and optical grating diffraction surface intersection point, and SG represents plane, grating 12 surperficial place, xq be grating quasi-synchronous tuning center of rotation Pq to the distance on SL plane, uq is that Pq is to the distance on SG plane.Wherein, the tuning center of rotation micrometer adjusting screw 9 of grating is the tuning center of rotation governor motion of described grating, laser frequency tuning micrometer adjusting screw 8 rotates governor motion for grating, and the tuning center of rotation Pq of grating is positioned on the central axis of the tuning center of rotation micrometer adjusting screw 9 of grating in the present embodiment.Move by regulating the moving plate 6 of the tuning center of rotation micrometer adjusting screw 9 drive grating adjusting brackets of grating, make the tuning center of rotation Pq of grating satisfy the requirement of above-mentioned relation formula (5) or (6), by regulating the moving plate 6 of laser frequency tuning micrometer adjusting screw 8 drive grating adjusting brackets the grating 12 on it is rotated, realize that grating 12 rotates around described tuning center of rotation Pq.
Below give one example and further specify, power 30mW wavelength is the laser beam that the semiconductor laser tube 1 of 689nm is sent, the process focal length is 4mm, after numerical aperture is 0.6 aspheric collimation lens, 3 collimations, to be incident on incisure density be 1800g/mm, have suitable diffraction efficiency, the groove size is that 12.5mm * 12.5mm, thickness are on the blazed diffraction grating 12 of 6mm, and for example incidence angle or the angle of diffraction are 38.917 °.The zeroth order diffraction light of grating 12 or direct mirror reverberation are as the output beam of laser.The first-order diffraction light of grating 12 is along the path reverse with former incident beam conllinear, and Yan Yuanlu turns back in the semiconductor laser tube 1.Semiconductor laser tube 1 adopts temperature sensor and semiconductor cooler to realize temperature control.Grating 12 is fixed on the moving plate 6 of adjusting bracket by grating frame 11, and this moving plate 6 can be adjusted by laser frequency tuning micrometer adjusting screw 8 and the tuning center of rotation micrometer adjusting screw 9 of grating decided at adjusting bracket on the plate 7.The tuning of optical maser wavelength realized by these diffraction grating 12 standards are rotated around simultaneous tuning center of rotation Pq.For example change light beams by laser frequency tuning micrometer adjusting screw 8 or piezoelectric ceramic 10 and incide angle on the diffraction grating 12, and the aligning adjustment of quasi-synchronous tuning center of rotation Pq and grating 12 can be sought and adjust by adjusting screw 9.
In this scheme, choose the Pq point and be positioned at the right side that P0 is ordered.Optical cavity length l=30mm wherein, then yq=37.2mm gets xq=22.3mm, and uq=17.3mm is arranged, and corresponding laser frequency simultaneous tuning scope can reach 4200GHz.Along with xq strengthens, namely tuning center of rotation Pq is away from the P0 point, and then simultaneous tuning scope will descend.For example: if xq=50mm, uq=38.9mm, laser frequency simultaneous tuning scope can reach 2800GHz.And if xq=100mm, uq=77.8mm, laser frequency simultaneous tuning scope also can reach 1900GHz.Even and xq=500mm, uq=389mm, laser frequency simultaneous tuning scope still can reach 800GHz.Can satisfy in the general application requirement to laser frequency simultaneous tuning scope fully.At this moment xq or uq value have covered the scope that the xq that can select in the general Littrow structure or uq can values.In fact, the laser frequency at this moment not continuous tuning coverage of mode hopping is mainly determined by other factors and parameter, plates the residual reflection state of anti-reflection film etc. such as semiconductor laser tube 1 surface of emission.
Semiconductor laser tube 1 in the such scheme also can be selected other wavelength, other power output, grating 12 also can adopt the grating of other type, such as: transmission grating or holographic grating etc., other incisure density and big or small thickness consist of, collimating lens 3 also can adopt other focal length and numerical aperture, and xq and uq value also can adopt other numerical value that satisfies formula (5).
Description of the invention is in order to provide for the purpose of example and the explanation, and is not exhaustively or limit the invention to disclosed form.Many modifications and variations are obvious for the ordinary skill in the art.Selecting and describing embodiment is for better explanation principle of the present invention and practical application, thereby and makes those of ordinary skill in the art can understand the various embodiment with various modifications that the present invention's design is suitable for special-purpose.
Claims (10)
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 200810127037 CN101609959B (en) | 2008-06-18 | 2008-06-18 | Littrow structure raster outer cavity semiconductor laser device and quasi-synchronization tuning method |
| US12/990,594 US9036668B2 (en) | 2008-06-18 | 2009-06-10 | Grating external-cavity semiconductor laser and quasi-synchronous tuning method thereof |
| PCT/CN2009/000642 WO2009152690A1 (en) | 2008-06-18 | 2009-06-10 | Grating external cavity semiconductor laser and its quasi synchronous tuning method |
| US13/188,592 US8681825B2 (en) | 2008-06-18 | 2011-07-22 | Grating external-cavity laser and quasi-synchronous tuning method thereof |
| US14/155,548 US8953649B2 (en) | 2008-06-18 | 2014-01-15 | Grating external-cavity semiconductor laser and quasi-synchronous method thereof |
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| CN 200810127037 CN101609959B (en) | 2008-06-18 | 2008-06-18 | Littrow structure raster outer cavity semiconductor laser device and quasi-synchronization tuning method |
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| CN112751259B (en) * | 2021-01-05 | 2022-06-21 | 中国人民解放军国防科技大学 | Class-synchronous tuning external cavity semiconductor laser based on flexible mechanical structure |
| CN113050403B (en) * | 2021-03-22 | 2022-06-14 | 湖北科技学院 | Low-microwave-power miniature CPT atomic clock light source generation device and method |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE29606494U1 (en) * | 1996-04-10 | 1997-05-07 | Sacher, Joachim, Dr., 35041 Marburg | Tuner |
| DE19544897C2 (en) * | 1995-12-01 | 2000-10-12 | Hannover Laser Zentrum | Semiconductor laser system that can be tuned without a jump in mode |
| CN1502153A (en) * | 2001-01-25 | 2004-06-02 | �����Ӣ��֪ʶ��Ȩ����˾ | Optical element |
| US20070223554A1 (en) * | 2006-03-09 | 2007-09-27 | Inphase Technologies, Inc. | External cavity laser |
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2008
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19544897C2 (en) * | 1995-12-01 | 2000-10-12 | Hannover Laser Zentrum | Semiconductor laser system that can be tuned without a jump in mode |
| DE29606494U1 (en) * | 1996-04-10 | 1997-05-07 | Sacher, Joachim, Dr., 35041 Marburg | Tuner |
| CN1502153A (en) * | 2001-01-25 | 2004-06-02 | �����Ӣ��֪ʶ��Ȩ����˾ | Optical element |
| US20070223554A1 (en) * | 2006-03-09 | 2007-09-27 | Inphase Technologies, Inc. | External cavity laser |
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