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双楔镜(Double Optical Wedge, DOW)腔长调节结构由两个楔角相同的楔镜组成,两楔镜以斜面平行对立的方式放置,如图1所示。双楔镜结构被放置于谐振腔光路中,光线以垂直楔镜直角面的方向穿过双楔镜。工作时,双楔镜结构通过楔镜在垂直方向的振动实现其内部光程的调节,即腔长(腔内光程)调节。
图1为双楔镜结构示意图,楔镜1和楔镜2的楔角相同,均为α,以斜面对立平行的方式放置,楔镜中间为空气隙,楔镜顶端绿色结构分别表示PZT1和PZT2,用以驱动楔镜1和楔镜2产生垂直位移。在驱动楔镜的过程中,光路在双楔镜结构内部的光程发生变化。将双楔镜结构放置在光学腔中,可实现腔长的微调节。由于楔镜质量一般在1 g以内(底面4 mm×4 mm、高4 mm的熔融石英楔镜,质量约为0.06 g),可以实现数百赫兹甚至数千赫兹的高频率振动。
设楔镜振动使双楔镜内部产生的光程变化量为ΔL。理论上,ΔL的大小与楔镜楔角角度α、楔镜折射率n、楔镜振动幅度Δh有关。假设双楔镜结构中楔镜1不动,楔镜2在PZT2的驱动下垂直振动,振幅为Δh,则楔镜2振动前后通过双楔镜内部的光路变化如图2所示。
图2中,左图实线表示静止时的楔镜对位置,虚线表示楔镜2垂直向上移动Δh后的位置,光线1和光线2分别表示楔镜2移动前和移动后通过楔镜内部的光线;右图为虚线框内光路详图。楔镜顶角为∠HGK = α,移动后楔镜2的顶点H与移动前楔镜2的顶点G的距离为HG = Δh,过H点做KH⊥HG,垂线交移动前楔镜2斜边于点K,KH = HG·tanα = Δhtanα,是楔镜2水平直角边的移动距离。
光从楔镜2入射,楔镜2出射。楔镜对静止时光线经过路径为IOABE,其中点I、O、A、B、E分别为入光线与楔镜1垂直面交点、斜面交点、楔镜2移动前斜面交点、楔镜2移动后的斜面交点、楔镜2垂直面交点;楔镜2向上移动后光线经过两个楔镜的路径为IOADF,其中点D、F分别为光线与移动后楔镜2的斜面交点、垂直面交点。做DC⊥BE,垂足为C,那么楔镜2移动前后,通过两楔镜的光程差为:
$$ \begin{split} \Delta L =& (IO \cdot n + OA + AB \cdot n + BC \cdot n + CE \cdot n) - \\ & (IO \cdot n + OA + AD + DF \cdot n) \\ \end{split} $$ CDEF为矩形,对边CE=DF,据此化简上式得:
$$ \Delta L = (AB + BC)n - AD = AC \cdot n - AD $$ 在直角ΔBCD中,∠BDC与楔镜顶角相等,∠BDC=α,那么直角BC边延长线与斜边BD组成的外角∠ABD=π/2+α。在ΔABD中,令∠BAD=θ,θ=θ′−α,其中θ′为光线从空气中进入楔镜斜面发射折射的入射角,α为折射角(α也是楔镜的顶角)。三角形内角和为π,∠ADB=π−(∠BAD+∠ABD)=π/2−θ′。四边形ABHK为平行四边形,所以AB = KH = Δh·tanα。综上,在ΔABD中,∠ADB=π/2−θ′,∠ABD=π/2+α,AB=Δh·tanα,根据余弦定理可知:
$$ \frac{{AD}}{{\sin \; \angle\; ABD}} = \frac{{AB}}{{\sin \; \angle \; ADB}} $$ 综合以上已知量可得:
$$ AD = \frac{{\sin \alpha }}{{\cos \theta '}}\Delta h $$ 在直角ΔACD中:
$$ AC = AD \cdot \cos \theta = \frac{{\sin \alpha \cos \theta }}{{\cos \theta '}}\Delta h $$ 将AC、AD代入光程差ΔL得:
$$ \Delta L = \Delta h\frac{{\sin \alpha }}{{\cos \theta '}}[n \cdot \cos (\theta ' - \alpha ) - 1] $$ (1) 式中:θ′为空气中的折射角,根据斯涅耳定律(Snell′s Law)可知:
$$ \theta ' = \arcsin (n\sin \alpha ) $$ (2) 式中:n为楔镜材料折射率。结合公式(1)和(2)可求得楔镜2在垂直方向上的位移对楔镜对内部光程的改变量。
然而,在实际使用过程中为了增加光程改变量ΔL,要求楔镜1和楔镜2均有位移量。经严格的数学推导,楔镜1和楔镜2同时存在位移的情况下,双楔镜内部光程改变量为:
$$ \left\{\begin{array}{l} \Delta L=\left(\Delta h_{1}+\Delta h_{2}\right) \dfrac{\sin \alpha}{\cos \theta ^{\prime}}\left[n \cos \left(\theta ^{\prime}-\alpha\right)-1\right] \\ \theta ^{\prime}=\arcsin (n \sin \alpha) \end{array}\right. $$ (3) 式中:Δh1和Δh2分别为楔镜1和楔镜2的振动幅度。公式(3)即为双楔镜腔长调节结构对腔长调节量的计算公式。
楔镜沿垂直方向振动实现内部光程调节的同时,也会在垂直方向上对出射光产生位移ΔH,即图2中光线2相对于光线1的垂直位移。经推导计算,垂直方向上的位移量为:
$$ \left\{ \begin{gathered} \Delta H = \left( {\Delta {h_1} + \Delta {h_2}} \right)\frac{{\sin \alpha \sin \left( {\theta ' - \alpha } \right)}}{{\cos \theta '}} \\ \theta ' = \arcsin \left( {n\sin \alpha } \right) \\ \end{gathered} \right. $$ (4) 线性谐振腔内,一般情况下,垂直方向上的光路位移不改变腔内振荡光路,不会造成谐振腔失调。环形谐振腔内,垂直方向上的光路位移会造成振荡光路产生失调角,但角度值极小,不影响谐振腔出光效率与光束指向性。以插入双角锥环形腔内双楔镜腔长调节结果为例,腔长840 mm,双楔镜参数Δh1+Δh2=9 μm,n =1.44, α = 30°,该情况下产生的振荡光失调角大小为0.000415°[10],角度极小,不影响谐振腔运行效率。因此,双楔镜腔长调节结构可以有效调节谐振腔内部光程,且不对腔的稳定性和出光指向性造成影响。
此外,需要注意的是,双楔镜腔长调节结构要求楔镜1和楔镜2具有相同的折射率和楔角,且斜面平行放置,否则将导致出射光和入射光不平行,使光路调节失去基准,增加光路调节难度。楔角不同时,相对于楔角较大楔镜一侧的光路,楔角较小楔镜一侧的光路向下偏转,如图3(a)所示,α1 > α2,出射光相对于入射光向下偏转。折射率不同时,相对于折射率较大楔镜一侧的光路,折射率较小楔镜一侧的光路向下偏转,如图3(b)所示,n1 > n2,出射光相对于入射光向下偏转,n1 < n2,出射光相对于入射光向上偏转。楔镜对斜面非平行放置情况如图3(c)所示,楔镜2沿楔镜顶点顺时针旋转,出射光相对于入射光向下偏转。
图 3 双楔镜楔角不同(a)、折射率不同(b)、斜面非平行放置(c)时出射光相对于入射光的偏转
Figure 3. Angles between the output light and the input light under DOW with different α (a), different n (b) and unparallel planes (c)
另外,静止状态下双楔镜斜面之间的空气隙(见图1)会在垂直方向上造成出射光相对于入射光的位移。根据计算,位移量大小ΔW(见图2)为:
$$ \left\{\begin{array}{l} \Delta W=\dfrac{\cos \; \theta^{\prime}}{\cos \; \alpha} \sin \left(\theta ^{\prime}-\alpha\right) l \\ \theta^{\prime}=\arcsin (n \sin \alpha) \end{array}\right. $$ (5) 式中:l为空气隙的宽度。根据公式(5),ΔW与l成线性关系。该位移量通常较小,不超过0.5 mm,不会对光路调节造成影响。以楔角α = 30°、折射率n = 1.5的楔镜对为例,空气间隙l = 1 mm时,出射光相对于入射光的垂直位移量仅为ΔW =0.0832 mm。此外,公式(5)中不含Δh,与楔镜振动幅度无关,不影响双楔镜结构对光程的调节。
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公式(3)给出了双楔镜结构对光程调节量ΔL的计算方法,据此可知影响调节量ΔL的因素有三个:楔镜楔角α、楔镜折射率n和楔镜振幅Δh1+Δh2。下面针对这三个变量对光程调节量ΔL的影响做讨论分析。
1)楔角α的大小对腔长调节量ΔL的影响。设楔镜基质材料为熔融石英,折射率n = 1.44,楔镜振幅Δh1+Δh2 = 1 μm,根据公式(3)可求得光程调节量ΔL与楔角α的关系,结果如图4所示。图4中,α从0°增加到42°,光程改变量从0 μm增加到0.54 μm。光程改变量ΔL与楔角α成正相关关系,且ΔL相对于α的斜率随α增大而增大。
2)楔镜折射率n对腔长调节量ΔL的影响。设楔镜楔角α = 30°,楔镜振幅Δh1+Δh2 = 1 μm,根据公式(3)可求得光程调节量ΔL与楔镜折射率n的关系,结果如图5所示。根据图5所示结果,n从1.2增加到2.0,ΔL从0.12增加到0.86,光程改变量ΔL与楔镜折射率n成正相关关系,且ΔL相对于n的斜率随n增大而增大。
3)楔镜振幅Δh1+Δh2对腔长调节量ΔL的影响。根据公式(3),ΔL与Δh1+Δh2成线性关系,Δh1+Δh2越大,ΔL越大,斜率大小由楔角α和折射率n决定。定义ΔL相对于Δh1+Δh2的斜率为双楔镜结构的调节系数,调节系数的大小表征了双楔镜结构光程调节能量的高低。
设α = 30°,n = 1.44,根据公式(3),ΔL与Δh1+Δh2的关系如图6所示,ΔL相对于Δh1+Δh2的斜率大小为0.28。
综上,光程调节量ΔL与楔镜楔角α、楔镜折射率n、楔镜振幅Δh1+Δh2均成正相关关系,即α、n、Δh1+Δh1越大,ΔL越大。为了获得更高的光程调节效率(即调节系数),需选用楔角大、折射率大的楔镜。
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在实际应用中,驱动双楔镜振动的器件通常为压电陶瓷(PZT),即图1所示绿色结构。压电陶瓷是一个电容器件,在电容量确定的情况下,加载其上的驱动电压和驱动频率成负相关关系。驱动电压决定了双楔镜的振动幅度,即Δh1+Δh1,驱动频率决定了双楔镜的调节频率。在高调节频率应用领域,如高重频单频脉冲注入锁定激光器,提高PZT调节频率且保持光程调节量ΔL不变,需要提高腔长调节系数,即ΔL相对于Δh1+Δh1的斜率。
1)折射率的设计。根据1.2节的结论,ΔL相对于Δh1+Δh1的斜率大小由楔角α和折射率n决定,选用折射率高的楔镜可获得更高的效率。表1给出了熔融石英(JGS1)、N-BK7/K9、钇铝石榴石(YAG)、金刚石(Diamond)四种常见光学材料的折射率[11]。设Δh1+Δh1 = 1 μm,根据公式(3),四种光学基质材料的双楔镜结构的光程调节效果如图7所示。
表 1 不同折射率光学材料楔镜对应的光学参数
Table 1. Parameters of wedges with different refractive indices
Optical material JGS1 N-BK7/K9 YAG Diamond Refractive index
@1.6 μm1.44 1.50 1.81 2.38 Total reflection critical angle 43.9° 41.8° 33.6° 24.7° Maximum adjustment
coefficient0.59 0.63 0.73 0.78 Brewster angle (dense
medium→rarer medium)34.7° 33.7° 29.0° 22.7° Adjustment coefficient
based on Brewster angle0.33 0.37 0.53 0.65 从图7中可以明显看出,基质材料折射率越大,相同楔角情况下双楔镜结构获得的调节量越大。图中,JGS1折射率n = 1.44、楔角α = 24°时的双楔镜光程调节量ΔL = 0.205 μm,对应调节系数为0.205,即楔镜在垂直方向上移动Δh1+Δh1 = 1 μm可实现双楔镜内部光程的增加/减少量ΔL = 0.205 μm。同样楔角值情况下,基质为金刚石(n = 2.38)的双楔镜结构可实现的调节量为0.782 μm,调节系数为0.782。因此,使用折射率大的楔镜可极大提高双楔镜的调节系数。
从折射率角度考虑,金刚石基质的双楔镜结构可以获得较高的调节系数。但在实际应用中,金刚石加工困难,价格高昂,作为楔镜基质并不适合。YAG折射率较大(相比于K9和JGS1),价格适中,加工难度低于金刚石,最高调节系数可达0.735(α = 33°时),是优异的楔镜基质材料。
2)楔角大小设计。根据1.2节的结论,楔角α越大,光程调节系数越大,双楔镜结构可获得更高的调节系数。入射光在楔镜斜面上的入射角大小等于楔镜的楔角α,如图8所示。由于入射角不能超过全反射角,楔角α不能大于楔镜的全反射角,即楔角α的最大值为楔镜侧面上的全反射角值,不同材料折射率见表1。
此外,楔角大小的设计还需考虑到双楔镜结构的光损耗率。为了减小光路的插入损耗,要求在楔镜直角面上镀0°增透膜,在斜面上镀光线入射方向为α的增透膜。对于一般光学材料,布儒斯特角大小与全反射角接近(见表1),因此可以将楔镜楔角α设计为布儒斯特角,从而在斜面不镀膜的情况下实现水平偏振光(p光)高透效果。在楔角为布儒斯特角的双楔镜结构中,光路调节系数接近于最大光路调节系数,尤其在折射率较大的情况下。另外,表1中,最大调节系数对应的楔镜楔角大小为全反射角,在实验中无法精确达到,所以将楔角设置为布儒斯特角,从实际光路调试、调节系数两方面考虑都是合适的。对于激光谐振腔之类的应用场景,这样的楔角设计可以帮助谐振腔实现水平偏振激光(p偏振)的输出。对于非谐振腔且光路非水平偏振光的应用场景,需要通过在楔镜斜面镀对应角度增透膜的方法来降低光损耗率。
上文确定了YAG为优异的楔镜基质材料,折射率1.81@1.6 μm。根据楔角大小设计原则,其楔角应为布儒斯特角29.0°(见表1)。因此,α = 29.0°、基质材料为YAG的双楔镜结构具有高调节效率和低光损耗率,调节系数为0.53。
综上,楔镜的折射率设计原则为:在不考虑加工难度和成本情况下,n越大,双楔镜结构的调节系数越高;楔镜楔角设计原则为:楔角α越大,调节系数越高,α最大值不超过楔镜全反射角,α值以布儒斯特角大小为宜。
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图1所示结构为双楔镜结构的典型样式,但双楔镜结构还存在其他不同的结构样式,下面针对几种常见变形样式进行分析讨论。
1)直角面对立结构。图12所示为直角面对立双楔镜结构,这种结构是图1所示斜面对立双楔镜结构的变形,即将图1中楔镜1和楔镜2互换位置后所得到的结构。
相比于斜面对立双楔镜结构,该结构的优点在于入射光线从楔镜斜面入射,入射角不受全反射角限制,角锥楔角大小不受全反射角限制;其缺点在于调节效率低。调节量ΔL可用公式(6)进行计算,其中α>θ′。
$$ \left\{ \begin{gathered} \Delta L = (\Delta {h_1} + \Delta {h_2})\frac{{\sin \alpha }}{{\cos \theta '}}[n - \cos (\alpha - \theta ')] \\ \theta ' = \arcsin \left(\frac{{\sin \alpha }}{n}\right) \\ \end{gathered} \right. $$ (6) 图13所示为楔镜振幅Δh1+Δh2 = 1 μm情况下两种结构的光程调节效果。结果表明,对于楔角确定的楔镜,斜面对立结构调节系数要大于直角面对立结构所获得的调节系数。实际应用中,楔角过大会导致斜面上增透膜透射效果较差,因此楔角一般不超过45°,这种情况下斜面相对的双楔镜结构有明显的效率优势。此外,直角面对立结构会导致出射光相对于入射光在垂直方向上产生较大位移,即产生较大的ΔH,不利于光路调节。
图 13 双楔镜斜面对立与直角面对立的光程调节结果
Figure 13. ΔL produced by DOW with opposite vertical plane and DOW with opposite inclined plane
2)基于正楔镜的双楔镜结构。图1和图12结构中所用楔镜结构均为直角楔镜,而基于正楔镜的双楔镜结构也可实现光程调节,其结构分为图14(a)和图14(b)所示。图14(a)结构的调节效率与图1所示结构效率大致相同,但出/入射光在垂直方向上的位移ΔH较大,且入射光从楔镜斜面进入楔镜,光路调节难度大;图14(b)结构调节系数低于图1结构的调节系数,在楔镜振幅相同的条件下,其调节量为cos(α/2)ΔL。
3)多级双楔镜结构。传统的腔长调节结构的工作方式是在腔镜粘贴PZT,直接驱动腔镜实现腔长调节,调节量ΔL = 2hcosθ(h为PZT振幅,θ为光线在腔镜上的入射角),调节系数为2cosθ。一般情况下,光线在腔镜上的反射角小于45°,对应调节系数大于1.4,如果在0°反射镜粘贴PZT,调节系数可达2,即PZT推进1 μm可实现2 μm的腔长调节。而双楔镜结构的调节系数较低,如图7所示的结果,一般不超过0.5,很难实现较大的光程调节。为了实现较大的光程调节量,可将多个双楔镜结构并列放置,形成多级双楔镜结构,如图15所示。多级双楔镜结构是通过增加楔镜行程的方式获得较大的光程调节量,但不改变调节系数。图15结构中楔镜行程为Δh1+Δh2+Δh3+Δh4,相比于图1结构,楔镜振幅提高了一倍,因此获得了多一倍的光程调节量。要获得更多的光程调节量,可增加双楔镜结构的级数。需要说明的是,多级双楔镜结构中,楔镜的个数必须为偶数,否则将造成出射光相对于入射光偏转,增加光路调节难度。
对比不同双楔镜结构的性质,图1所示斜面对立放置的双楔镜结构具有调节效率高、光损耗低(尤其是以布儒斯特角为楔角的楔镜)、光路调节容易的特点,是实际应用的最佳选择。要实现更大光程调节量,可采用图15所示多级双楔镜结构。不同结构的双楔镜腔长调节性质如表2所示。
表 2 不同双楔镜结构的性能比较
Table 2. Comparison of properties for different DOWs
DOWs Adjustment coefficient ΔH Insertion loss Optical path construction High Small Low Easy Low Large High Difficult High Large High Difficult Low Small Middle Middle High Very small Middle Middle
Study on cavity length adjustment configuration of double optical wedge
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摘要: 腔长微调节结构在光学谐振器里有重要应用。一种由双楔镜组成的腔长微调节结构被提出,该结构可实现不依赖于腔镜的腔长调节。双楔镜结构由斜面平行对立放置的两个直角楔镜构成,通过在垂直方向上驱动楔镜移动实现双楔镜内部光程改变,进而改变所处谐振腔内光路的光程。双楔镜结构对光程改变量的理论计算公式被建立,根据公式,光程改变量与楔镜楔角大小成正相关关系,与楔镜折射率成正相关关系,与楔镜振幅成线性关系。楔镜的楔角和折射率共同决定双楔镜结构的光程调节效率。经理论设计,楔角29°、折射率1.81的YAG双楔镜结构具有较高的调节效率和较小的光损耗,调节系数为0.53。实验上,以双角锥环形腔为基础,实现了双楔镜结构对腔长的调节,验证确定了双楔镜结构对腔长调节的可行性和有效性。讨论分析了双楔镜结构的变形结构:直角面对立双楔镜结构、基于正楔镜的双楔镜结构、多级双楔镜结构的光程调节性能。对比了双楔镜结构和其变形结构在光程调节效率、光损耗、光路调节难易程度的性能,确定了各种双楔镜结构在实际应用中的优缺点,为双楔镜结构的设计和选择提供了参考依据。Abstract:
Objective The cavity length adjustment configuration has important applications in optical resonators. A cavity length adjustment configuration of double optical wedge (DOW) is proposed, which can adjust the cavity length independently of the cavity mirror. DOW configuration is composed of two right-angle wedges with beveled planes placed in parallel opposites. The optical path inside DOW is changed by driving the wedges to move in the vertical direction, and then the optical path in the resonator is changed. The theoretical formula for calculating the change of optical path of DOW configuration is established. According to the formula, the change of optical path is positively correlated with the wedge angle, the refractive index of wedge and the wedge displacement in the vertical direction. The wedge angle and refractive index determine the optical path adjustment efficiency of DOW configuration. According to the theoretical design, the YAG DOW configuration with wedge angle of 29° and refractive index of 1.81 has higher adjustment efficiency and less optical loss, and the adjustment coefficient is 0.53. In the experiment, the double corner cube retroreflector (DCCR) ring cavity is used to verify the cavity length adjustment, and the feasibility and effectiveness of DOW configuration to adjust the cavity length are verified. The deformable structure of DOW configuration is discussed and analyzed. The optical path adjustment properties of DOW configuration with beveled planes placed in parallel opposites, regular optical wedges and cascaded DOW configuration are discussed. The performances of DOW configuration and its deformed configuration in optical path adjustment efficiency, optical loss and the complexity of the optical path construction are compared, and the advantages of these DOW configurations in practical application are determined, which provides a reference for the design and selection of DOW configuration. Methods In theory, by geometric calculation, the calculation formula of the optical path adjustment of the DOW configuration is derived, and the results are shown in Eq.(3). According to Eq.(3), there are three factors affecting the adjustment ΔL, namely wedge angle α, wedge refractive index n, and wedge displacement Δh1+Δh2 in the vertical direction. The larger the wedge angle value of α is, the higher the adjustment efficiency is, and the data results are shown (Fig.4); The greater the refractive index n is, the higher the adjustment efficiency is, and the data results are shown (Fig.5). The larger the displacement Δh1+Δh2 is, the higher the adjustment efficiency is. According to these factors, a DOW configuration with wedge angle α = 29° and material YAG is designed, and its adjustment coefficient is 0.53. Results and Discussions The adjustment effect of DOW configuration to the cavity length is verified experimentally by using the DCCR ring cavity. The reflector of DCCR ring cavity is corner cube retroreflector, which can not be drived by PZT directly, thus the cavity length adjustment of DCCR ring cavity can be realized with DOW configuration. The experimental setup is shown (Fig.10). DOW configuration is inserted into the DCCR ring cavity, and 1.6 μm laser is injected into the cavity. When DOW configuration is operating, 1.6 μm laser will form a resonance signal and output from M3, through which the cavity length adjustment value ΔL caused by DOW configuration can be determined. The experimental results are shown (Fig.11). The appearance of resonance signal proves that the cavity length changes, and the change value ΔL is consistent with the theoretical expectation. The above experimental results prove that DOW configuration is effective in adjusting the cavity length. Conclusions In this paper, a DOW configuration is proposed, which can be used in the special scenario where the cavity length cannot be adjusted by driving the cavity mirrors. The formula for calculating the adjustment value and adjustment coefficient of DOW configuration is given theoretically. The influence of wedge angle and refractive index on the adjustment efficiency is analyzed. DOW configuration with wedge angle of 29° and matrix of YAG is designed. DOW configuration has a large adjustment efficiency (adjustment coefficient is 0.53) and a small light loss, and is the better choice in various DOW configurations. The cavity length adjustment of the length of DOW configuration is realized experimentally in a double-corner cone ring cavity, which verifies the feasibility and effectiveness of the DOW configuration. Finally, different deformation structures of DOW configurations are given, and the property parameters of each deformation structure are compared. Compared with the traditional cavity length adjustment configuration, cavity length adjustment configurations of DOW has low adjustment efficiency and certain insertion loss, but it provides an adjustment mode independent of the cavity mirror, and provides a new choice for the cavity length adjustment in special application scenarios. -
Key words:
- double optical wedge /
- cavity length adjustment /
- wedge prism /
- PZT
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表 1 不同折射率光学材料楔镜对应的光学参数
Table 1. Parameters of wedges with different refractive indices
Optical material JGS1 N-BK7/K9 YAG Diamond Refractive index
@1.6 μm1.44 1.50 1.81 2.38 Total reflection critical angle 43.9° 41.8° 33.6° 24.7° Maximum adjustment
coefficient0.59 0.63 0.73 0.78 Brewster angle (dense
medium→rarer medium)34.7° 33.7° 29.0° 22.7° Adjustment coefficient
based on Brewster angle0.33 0.37 0.53 0.65 表 2 不同双楔镜结构的性能比较
Table 2. Comparison of properties for different DOWs
DOWs Adjustment coefficient ΔH Insertion loss Optical path construction High Small Low Easy Low Large High Difficult High Large High Difficult Low Small Middle Middle High Very small Middle Middle -
[1] Drever R W P, Hall J L, Kowalski F V, et al. Laser phase and frequency stabilization using an optical resonator [J]. Appl Phys B, 1983, 31(2): 97-105. [2] Chen C, Wang Q, Huang S, et al. Single-frequency Q-switched Er: YAG laser with high frequency and energy stability via the Pound-Drever-Hall locking method [J]. Optics Letters, 2020, 45(13): 3745-3748. doi: 10.1364/OL.396501 [3] Henderson S W, Yuen E H, Fry E S. Fast resonance-detection technique for single-frequency operation of injection-seeded Nd: YAG lasers. [J]. Optics Letters, 1986, 11(11): 715-717. doi: 10.1364/OL.11.000715 [4] Dai T Y, Ju Y L, Yao B Q, et al. Injection-seeded Ho: YAG laser at room temperature by monolithic nonplanar ring laser [J]. Laser Physics Letters, 2012, 9(10): 716-720. doi: 10.7452/lapl.201210072 [5] Xue J, Chen W, Pan Y, et al. Pulsed laser linewidth measurement using Fabry-Perot scanning interferometer [J]. Results in Physics, 2016, 6: 698-703. doi: 10.1016/j.rinp.2016.10.004 [6] Ciurylo R, Brym S, Jurkowski J, et al. Response of scanning Fabry-Pèrot interferometer to the speed dependent Voigt profile [J]. Journal of Quantitative Spectroscopy & Radiative Transfer, 1995, 53(5): 493-500. [7] Zavracky P M, Denis K L, Xie H K, et al. Micromachined scanning Fabry-Perot interferometer [C]//Proceedings of SPIE-The International Society for Optical Engineering, 1998, 3514: 179-187. [8] Wang K, Gao C, Lin Z, et al. 1 645 nm coherent Doppler wind lidar with a single-frequency Er: YAG laser [J]. Optics Express, 2020, 28(10): 14694-14704. doi: 10.1364/OE.392092 [9] Wu J, Wang Y, Dai T, et al. Single-longitudinal-mode generation in a Ho: YLF ring laser with double corner cubes resonator [J]. Infrared Physics & Technology, 2018, 92: 367-371. [10] Zhang Z G. Research on double corner cube ring cavity and its application in pulsed injection-locking laser[D]. Harbin: Harbin Institute of Technology, 2022. (in Chinese) [11] RefractiveIndex. INFO. Refractive index database [EB/OL]. [2023-07-17]. https://refractiveindex.info/. [12] Zhang Z G, Ju Y L. Injection-seeded Q-switched laser based on a double corner cube retroreflector ring cavity [J]. Optics Express, 2021, 29(25): 41954-41963. doi: 10.1364/OE.446151 [13] Zhang Z G, Ju Y L. Theoretical and experimental studies of output coupling ratio tunable double-corner-cube-retroreflector ring cavity [J]. Journal of the Optical Society of America B, 2021, 38(10): 2847-2854. doi: 10.1364/JOSAB.438587