基于马赫曾德干涉光路的光压测量装置设计

基于马赫曾德干涉原理,设计搭建了可调制与放大干涉条纹的光压测量装置.由频率和功率可调制脉冲激光产生光压,使真空中两面高反镀铝薄膜产生微小形变(位移),从而使由氦氖激光器发射、经半反半透镜分束的参考光和信号光的光程差改变,即干涉条纹发生改变.用CCD记录干涉条纹位移量,数据处理获得干涉条纹位移量和薄膜形变量的关系,计算出脉冲激光在薄膜处的光压.分别讨论了脉冲激光入射角度、频率等参量对检测结果的影响,并通过双角度入射方法消除了热辐射效应的影响.该检测装置可测得最小光功率为15.0mW所产生的光压大小为13.42μPa,线性工作范围为15.0mW(13.42μPa)至200mW(1179μPa),且工作稳定、灵敏度高,测量结果准确.     

热透镜效应对半整块腔型中二次谐波过程的影响

二次谐波过程是制备高功率、宽波长范围激光的有效途径.在二次谐波过程中,晶体的热透镜效应是限制转换效率进一步提高的重要因素,热透镜效应对二次谐波转换效率的影响随着基频光功率的增大而加剧.本文理论分析了不同半整块腔型中热透镜效应对转换效率的影响关系;实验上搭建了两种腔型进行高效外腔倍频制备532 nm激光,测量其倍频转换效率随基频光功率的变化关系.对于平凹型半整块腔,在输入光功率为800 mW时,产生747 mW的532 nm激光输出,得到最佳的转换效率为93.4%±3%;对于双凹型半整块腔,在输入光功率为600 mW时,产生529 mW的532 nm激光输出,得到的最佳转换效率为88.2%±3%.研究表明,热透镜效应对双凹型半整块腔的转换效率影响相对较大,且随着腔内损耗的增加而加剧;相比于双凹型半整块腔,平凹型结构可以实现更高效的倍频转换.本文的理论及实验结果可在量子信息科学、光学频率计量以及生物医学等领域的研究中发挥重要作用.     

用于氢原子1S-2S光谱研究的超窄线宽243nm半导体激光

近年来,随着激光稳频技术的发展,人们可以把972nm的外腔半导体激光器产生的激光进行放大和四倍频,并将它锁定到超稳定的光学法布里-珀罗腔上,从而可以获得Hz量级超窄线宽的243nm激光,使其成为研究氢原子1S-2S双光子跃迁的有力工具.文章主要介绍了超稳腔、四倍频243nm半导体激光器的研究进展及在氢原子1S-2S双光子跃迁精密光谱研究中的应用.     

利用腔内四能级原子相干效应实现全光学信号存储

在光学腔与四能级原子组成的非线性光学双稳系统中，利用调谐于不同能级附近的控制信号光脉冲可以使光学腔模产生“IT”或“负”的非线性相移，从而实现了光学双稳迟滞曲线的受控移动及双稳“高态”与“低态”之间的可控跃变，基于上述效应，完成了光学信号的全光存储与腔输出状态的低功率控制开关．这一结果为全光及量子信息处理提供了新的可供利用的物理机制．     

耦合腔结构可调谐双频固体激光器的研究

研究了一种激光二极管(LD)抽运的频差可调谐双频固体激光器,对耦合腔实现双频的方法进行了分析。实验中使用输入镜与腔内插入标准具形成耦合腔实现单频运转,双λ/4波片使单纵模激光频率分裂,通过改变两个λ/4波片快轴之间的夹角来实现频差调谐。在LD抽运光功率为290mW的条件下,获得了频差在0～1.1GHz范围内可调、功率为34mW的双频激光输出。     

激光二极管双端直接抽运混合腔板条激光器

为减少热透镜效应的影响, 获得高光束质量的激光, 本文利用激光二极管阵列双端直接抽运Nd:YVO₄, 采用负支共焦折叠混合腔结构, 获得最高功率为416 W 1064 nm的激光输出, 光–光转换效率为54.3%, 斜效率为61.6%. 在输出功率为370 W时, 光束质量因子M²在非稳腔和稳腔方向上分别为3.9和4.7.     

端面泵浦双Nd∶YVO_4激光器中热效应对腔稳定性的影响

利用多个激光晶体串接方式可以提高固体激光器的输出功率 发展双Nd∶YVO4 晶体激光器 ,将晶体的端面镀膜作为谐振腔的端面镜 ,构成了平行平面谐振腔 对平行平面谐振腔的等效腔进行了理论分析 ,结果表明激光晶体吸收泵浦光产生的热透镜效应对保持腔的稳定性起到了重要的作用 在国内首次进行了双端泵浦双Nd∶YVO4 激光器的实验研究 ,在抽运功率为 2 0 .74W时获得了 11W的 10 6 4nmTEM0 0 模激光输出 ,其光 光转化效率约为 5 3% 并且对于不同掺杂浓度下的实验结果进行了讨论     

非线性吸收诱导掺镱光纤激光器中的光学双稳

研究了在掺镱光纤激光器中观察到的光学双稳态现象.激光信号光和驻留泵浦光的双稳特性来源于激光器在小信号和增益饱和两种情况下,掺镱光纤对信号的非线性吸收导致的激光器内腔非线性损耗.同时分析了把泵浦光中的光学双稳行为通过分叉的腔结构扩展到切换式双波长光纤激光器的可行性.     

基于双频泵浦正常色散富硅氮化硅微环谐振腔的光频率梳设计

提出一种利用锁相双频激光作为泵浦源输入正常色散富硅氮化硅微环谐振腔产生光频率梳的方案。对富硅氮化硅微环谐振腔进行色散调控,实现1550 nm波段平坦正常色散优化设计。利用LLE (Lugiato Lefever equation)方程进行光频率梳产生仿真,分析改变泵浦失谐时光频率梳产生的时域和频域演化过程。同时,探究各项参数对光频率梳产生的影响,包括泵浦功率、双频激光功率占比、微腔波导损耗、微腔色散、双频激光频率间隔。仿真实现的光频率梳带宽可覆盖1520 nm到1580 nm。     

高功率CO_2激光器高反膜耦合窗热效应研究

为解决CO2激光器高反膜耦合窗在腔内高功率激光作用下产生的热效应问题,对耦合窗的温度场和热形变场进行了理论分析研究。通过谐振腔工作状态分析,首次提出了腔内振荡激光具有混合模式分布的表达式,并利用半解析热分析方法得出了在混合模式下耦合窗产生的温度场和热形变场的一般表达式,同时与将腔内激光分布作均匀分布、高斯分布假设下耦合窗的情况作了对比分析。研究结果,当腔内谐振功率为3800W、腔内激光混合模式分布时,耦合窗内表面中心最大热形变量约为0.91μm,作均匀分布、高斯分布假设分别造成最大热形变量偏小20.88%,偏大78.02%。     

Manipulating a micro-cantilever between its optomechanical bistable states in a lever-based Fabry-Pérot cavity

In this paper, we demonstrate experimentally switching a cantilever between its optomechanical bistable states in a low finesse optical cavity. Our experiment shows that the deformation of cantilever can be manipulated by tuning the cavity resonance. When the laser power increases across the threshold value of 110 ?W, optomechanical bistability is induced by strong static photothermal backaction at room temperature. Numerical calculation revealed that the bistable effect originates from the multi-well potential created via the optomechanical interaction. Switching of the cantilever between the bistable states was achieved by tuning the cavity to the corresponding boundaries of the bistable region, where the barrier between the bistable states vanishes.     

Controllable optical bistability in a three-mode optomechanical system with a membrane resonator

We study the optical bistability(OB) in a three-mode cavity optomechanical system, where an oscillating membrane of perfect reflection is inserted between two fixed mirrors of partial transmission. By investigating the behavior of steady state solutions, we find that the left and right cavities will exhibit the bistable behavior simultaneously in this optomechanical system by adjusting the left and right coupling fields. In addition, one can control the OB threshold and the width of the OB curve via adjusting the coupling strength, the detuning, and the decay rate. Moreover, we further illustrate the OB appearing in the cavity by the effective potential as a function of the position.     

Bistability in a Hybrid Optomechanical System under the Effect of a Nonlinear Medium

We investigate a hybrid optomechanical system consisting of two coupled cavities, one of them is composed of two-end fixed mirrors(called the traditional cavity), and the other has a one-end oscillating mirror(named as the optomechanical eavity). A Kerr medium is inside the traditional cavity to enhance the nonlinearity due to the fact that it can cause observing of bistable behavior in intracavity intensity for the optomechanical cavity.The Hamiltonian of the system is written in a rotating frame and its dynamics is described by quantum Langevin equations of motion. Our proposed s.ystem exhibits unconventional plots for the mean photon number of the optomechanical cavity which are not observed in previous works. The present results show a deep effect of the Kerr medium on optical bistability of intracavity intensity for the optomechanical cavity. Also, coupling strength of the cavities can effectively change the stability of the system.     

Quantum coherence transfer between an optical cavity and mechanical resonators

This study highlights the theoretical investigation of quantum coherence in mechanical oscillators and its transfer between the cavity and mechanical modes of an optomechanical system comprising an optical cavity and two mechanical oscillators that,in this study, were simultaneously coupled to the optical cavity at different optomechanical coupling strengths. The quantum coherence transfer between the optical and mechanical modes is found to depend strongly on the relative magnitude of the two optomechanical couplings. The laser power, decay rates of the cavity and mechanical oscillators, environmental temperature, and frequency of the mechanical oscillator are observed to significantly influence the investigated quantum coherences. Moreover,quantum coherence generation in the optomechanical system is restricted by the system's stability condition, which helps sustain high and stable quantum coherence in the optomechanical system.     

Generating large steady-state optomechanical entanglement by the action of Casimir force

In this paper,we study an optomechanical device consisting of a Fabry-P′erot cavity with two dielectric nanospheres trapped near the cavity mirrors by an external driving laser.In the condition where the distances between the nanospheres and cavity mirrors are small enough,the Casimir force helps the optomechanical coupling to induce a steady-state optomechanical entanglement of the mechanical and optical modes in a certain regime of parameters.We investigate in detail the dependence of the steadystate optomechanical entanglement on external control parameters of the system,i.e.,the effective detuning,the pump powers of the cavity,the cavity decay rate and the wavelength of the driving field.It is found that the large steady-state optomechanical entanglement,i.e.EN=5.76,can be generated with experimentally feasible parameters,i.e.the pump power P=18.2μW,the cavity decay rateκ=0.5 MHz and the wavelength of the laserλL=1064 nm,which should be checked by optical measurement.     

Entanglement of movable mirror and cavity field enhanced by an optical parametric amplifier

A scheme to generate entanglement in a cavity optomechanical system filled with an optical parametric amplifier is proposed. With the help of the optical parametric amplifier, the stationary macroscopic entanglement between the movable mirror and the cavity field can be notably enhanced, and the entanglement increases when the parametric gain increases.Moreover, for a given parametric gain, the degree of entanglement of the cavity optomechanical system increases with increasing input laser power.     

级联型四能级原子相干介质中的光学双稳态和多稳态

主要研究了在一单向环形腔内的级联型四能级原子被三个光场驱动的光学双稳态和多稳态行为. 三个单模光场通过三个光子跃迁路径与原子系统耦合. 在这种情况下,中间两能级间所加的耦合场Ω_B变得非常重要. 研究显示耦合场Ω_B的增加会使光学双稳态的阈值减小,同时也会导致光学多稳态的产生.对上面两能级间所加的耦合场的作用也进行了讨论,同时还讨论了探测场失谐和合作参数对光学双稳态及多稳态的影响. 关键词： 原子相干 光学双稳态和多稳态 四能级原子     

掺Yb钒酸盐晶体激光振荡中的光学双稳态现象研究

研究了三种掺Yb钒酸盐晶体Yb:LuVO4,Yb:YVO4和Yb:GdVO4的激光振荡中所呈现的光学双稳态效应.以晶体所吸收的抽运功率表征的双稳区宽度ΔPabs可超过1W,在双稳区高功率一侧的边界,即激光振荡的上阈值点,出现激光输出功率的不连续变化或跃变,同时发生亚毫秒时间尺度上的大幅度强度涨落.谐振腔的输出耦合透过率、晶体长度、晶体中的热效应等对双稳态效应均具有重要影响.     

非线性光学腔中的相位调制光机械动力学

研究了Fabry-Perot光学腔中包含一个光学参量放大器来增强腔场与机械振子之间的耦合的光机械动力学行为.在解析边带机制下用量子郞之万方程具体研究了振子的涨落光谱、光学多稳态行为、机械阻尼与修正共振频移和基态冷却.通过数值解讨论了辐射压力诱导机械振子和腔场的稳态振幅所展现的光学多稳态行为,同时也分析了辐射压力引起的修正共振频移和机械阻尼与参量增益、输入激光功率和参量相位这三个因素的关系.此外,随着调节泵浦场的参量相位,振子的涨落光谱呈现简正模式分裂.通过精确求解最终有效声子数论证了基态冷却.结果表明,机械振子的冷却由初始浴温度、机械品质因数和参量相位这个三个因素控制.参量相提供一个新的方法来操控非线性光机械动力学.