双光力诱导透明窗口的可调特性

提出一个杂化腔光力系统理论方案,利用两纳米机械振子间的库仑耦合作用实现弱探测光的双光力诱导透明窗口.研究边带可分辨区域和红失谐情况下双光力诱导透明窗口的可调特性.数值计算表明:两纳米振子间的库仑作用可有效地使单光力诱导透明窗口劈裂为双透明窗口.随着库仑耦合强度的增大,两透明窗口间的距离对称性地拉大;其次,光力腔衰减率的改变对两透明窗口的位置和深度无影响,仅对两透明窗口的宽度产生细微改变,测量精度可在坏腔情形下得到很好的保持;另外,仅增加参量放大器的非线性增益参量将使两透明窗口变宽,而引入驱动参量放大器的光场相位,利用相位匹配可以产生比空腔情形更加狭窄陡峭的双透明窗口,可用于比空腔情况更加精密的测量.     

相干反馈相位对腔光力系统中正交模劈裂的影响

强耦合是腔光力系统用于产生和观察许多宏观量子现象（如光力压缩态和纠缠态等）的基本条件，系统进入强耦合的明显标志是正交模劈裂。本文理论分析了加入光学参量放大器和相干反馈的光力系统中的正交模劈裂现象，并讨论分析了反馈回路的光学相位对正交模劈裂的影响。在不同参数情况下，如光学参量放大器参量增益、反馈分束器的反射系数和输入光功率等，模式位置和线宽随相移的变化。结果表明：在其他参数一定时，通过调节反馈相位，初始无模式劈裂的系统随相位变化出现模式劈裂并达到最大的模式间隔，从而从弱耦合进入强耦合状态。而且，多个参数的协同调节，可有效提高模式劈裂的程度。该研究为实验上增强光力耦合强度的实验调节提供了方便，可广泛用于光力系统的弱力灵敏探测以及宏观量子态产生与测量等。     

原子辅助光力系统中快慢光的量子调控

随着纳米科技以及半导体技术的迅猛发展,光力诱导透明、快慢光和光存储以及其他在光力系统中发现的量子光学和非线性光学效应成为人们目前研究的热点.本文将薄膜腔光力系统同被束缚在腔中的二能级冷原子系综相耦合,通过直接在薄膜振子上引入弱辅助驱动场来研究该原子辅助光力系统中原子和相位对量子相干性质及其快慢光的调控.经过分析发现,通过改变辅助驱动场的强度可直接实现对光力诱导透明窗口深度的调控,通过改变辅助场与探测场之间的相位差,可实现输出的探测场在"吸收"、"透明"和"增益"之间相互转换,进而对弱探测场进行动态调控实现光开关.与此同时,还发现系统的群延迟时间随相位差的改变呈周期性变化.通过调节相位差及原子数,不但可以改变群延迟时间,还可实现快慢光之间的相互转换.     

利用自制的单频激光器获得近通讯波段正交振幅压缩态光场

利用自制的1.34 μm和0.67 μm双波长输出单频激光器作为泵浦源,泵浦基于PPKTP晶体的光学参量放大器,通过边带锁频技术将光学参量放大腔腔长锁定在激光频率上,将泵浦光和信号光相对相位锁定在π相位,经参量缩小过程获得低于散粒噪声极限约3 dB的正交振幅压缩光.压缩光位于光纤通信窗口——1.3 μm波段.     

基于BiB3O6晶体的飞秒光参量变换特性

对基于新型非线性晶体BiB₃O₆(BIBO)的飞秒光参量变换过程的参量特性进行了研究. 计算了BIBO晶体三个光学主平面内的相位匹配条件和有效非线性系数,确定了克尔透镜锁模钛宝石激光器的基频光与倍频光抽运时最佳的光学主平面和相位匹配方式,并分析了三波的时间走离和空间走离,以及信号光的参量增益和带宽. 为利用基于BIBO晶体的飞秒光参量技术获得高能量、宽调谐、窄脉宽的光源提供理论依据和实验指导. 关键词： 3O₆')" href="#">BiB₃O₆ 光参量变换 共线相位匹配 光学主平面     

基于光参量放大相位共轭特性的图像修复与增强

非线性光学相位共轭技术可将经过散射介质后产生畸变的光学波前进行修复.本文基于光参量放大(OPA)过程的光学相位共轭(OPC)特性,进行了光学相位共轭图像修复和增强的实验研究.基于大能量532 nm皮秒抽运激光和大口径非线性光学晶体KTiOPO_4(KTP)(Ⅱ类相位匹配),对经过牛奶乳浊液后已无法识别的1064 nm近红外光学图像,进行相位共轭修复,修复后的图像分辨率达12线/mm,此外,结合OPA过程的光学增益特性,实现了超过17 dB的光学图像增强,为现有三波混频光学相位共轭修复畸变所获图像增益的最大值.在此基础上,峰值信噪比较修复之前有160%的提升.考虑到光参量过程所具有的波长可调谐特性,在实际应用中,可根据需要,选择与生物组织的光学治疗窗口相匹配的成像波长,从而保证更长的穿透深度,提升生物组织成像和医学无损检测的效果.     

回音壁微腔光力系统的相干控制与完全相干透射

本文研究了两侧同时输入的回音壁模谐振双微腔光力系统中电磁诱导透明的相干调控.通过改变双微腔两侧探测场的强度比值及相位差,可以有效控制电磁诱导透明窗口的宽度和深度,对探测场的吸收和色散等性质实施显著的影响,并且能够在特殊频率处产生关于探测场的完全相干透射现象.     

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.     

利用周期性极化KTiOPO4晶体参量缩小过程产生明亮振幅压缩光

利用周期性极化KTiOPO₄晶体构成的连续准相位匹配简并光学参量缩小谐振腔， 获得了注入红外的明亮正交振幅压缩光.参量振荡阈值为35mW.当抽运光功率为20mW时，测得压缩度为223dB，特别是当抽运光功率为8mW时，测得压缩度为217dB. 关键词： 准相位匹配 简并光学参量放大器 明亮振幅压缩光     

磁光非线性光纤中光参量增益的研究

将光纤中磁光效应和非线性效应作为微扰,推导了磁光四波混频的耦合模方程.通过解析解研究了各向同性磁光非线性光纤的参量过程,并指出利用磁光耦合系数的色散特性可以实现四波混频的相位匹配.同时,采用龙格-库塔法分析了在线双折射磁光非线性光纤中,忽略费尔德常量的波长依赖性时,左旋圆偏振光参量增益的磁控特性,指出了实验中采用较高费尔德常量的非线性光纤的必要性.研究表明:1)对于低线双折射磁光非线性光纤,优化双折射大小可以获得最大的参量增益;2)根据参量增益对磁光耦合系数的单调依赖特性,适当选择光纤长度、泵浦功率以及输入导波光的偏振态,可使参量增益的磁可调范围大大提高.     

Perfect optomechanically induced transparency in two-cavity optomechanics

Here, we study the controllable optical responses in a two-cavity optomechanical system, especially on the perfect optomechanically induced transparency (OMIT) in the model which has never been studied before. The results show that the perfect OMIT can still occur even with a large mechanical damping rate, and at the perfect transparency window the long-lived slow light can be achieved. In addition, we find that the conversion between the perfect OMIT and optomechanically induced absorption can be easily achieved just by adjusting the driving field strength of the second cavity. We believe that the results can be used to control optical transmission in modern optical networks.     

Electromagnetically induced transparency-like effect in the degenerate triple-resonant optical parametric amplifier

We investigate experimentally the absorptive and dispersive properties of the triple-resonant optical parametric amplifier (OPA) for the degenerate subharmonic field. In the experiment the subharmonic field is utilized as the probe field and the harmonic wave as the pump field. We demonstrate that the electromagnetically induced transparency (EIT)-like effect can be simulated in the triple-resonant OPA when the cavity linewidth for the harmonic wave is narrower than that for the subharmonic field. However, this phenomenon cannot be observed in a double-resonant OPA. The narrow transparency window appears in the reflected field. Especially in the measured dispersive spectra of the triple-resonant OPA, a very steep variation of the dispersive profile of the subharmonic field is observed, which can result in a slow light as that observed in an atomic EIT medium.     

Starspots,stellar cycles and stellar flares: Lessons from solar dynamo models

We theoretically investigate the multistable behavior of a hybrid optomechanical system,in which a charged mechanical resonator is coupled via Coulomb interaction to an optomechanical cavity containing an optical parametric amplifier(OPA).It is shown that the multistable behavior of the mean intracavity photon number can be controlled flexibly by adjusting the nonlinear gain parameter of the OPA,the phase of the field pumping the OPA,the power and frequency of the field driving the cavity,and the Coulomb coupling strength between the two charged mechanical resonators.In particular,the increase of the nonlinear gain parameter can result in a transition from testability to Instability.Moreover,the effect of the Coulomb coupling strength on the bistable behavior of the steady-state positions of the two mechanical resonators is discussed.     

Ideal optomechanically induced transparency generation in a cavity optoelectromechanical system

The ideal optomechanically induced transparency effects of an output probe field are investigated in a cavity optoelectromechanical system, which is composed of an optical cavity, a charged mechanical resonator, and a charged object.Although the charged mechanical resonator damping rate is nonzero, the ideal optomechanically induced transparency can still appear due to the non-rotating wave approximation effect in the system. The location of optomechanically induced transparency dip can be controlled via the Coulomb coupling strength. In addition, we find that both the transparency window width and the maximum dispersion curve slope are closely related to the optical cavity decay rate.     

Controllable Photon Transport in a Three-Mode Optomechanical System with the Non-Rotating Wave Approximation Effect

We propose a scheme for realizing controllable photon transport in a three-mode optomechanical system comprising one cavity and two mechanical modes. We found that the non-rotating wave approximation effect can cause the ideal optomechanically induced transparency of the output field. The effects of the cavity mode decay rate on the width of the optomechanically induced transparency window, the dispersion curve slope are discussed in the resolved sideband regime and the unresolved sideband regime.

     

Tunable optomechanically induced transparency and fast–slow light in a loop-coupled optomechanical system

We theoretically explore the tunability of optomechanically induced transparency(OMIT) phenomenon and fast–slow light effect in a loop-coupled hybrid optomechanical system in which two optical modes are coupled to a common mechanical mode. In the probe output spectrum, we find that the interference phenomena OMIT caused by the optomechanical interactions and the normal mode splitting(NMS) induced by the strong tunnel coupling between the cavities can be observed. We further observe that the tunnel interaction will affect the distance and the heights of the sideband absorption peaks. The results also show that the switch from absorption to amplification can be realized by tuning the driving strength because of the existence of stability condition. Except from modulating the tunnel interaction, the conversion between slow light and fast light also can be achieved by adjusting the optomechanical interaction in the output field. This study may provide a potential application in the fields of high precision measurement and quantum information processing.     

Compact surface plasmon amplifier in nonlinear hybrid waveguide

Surface plasmon polariton(SPP), a sub-wavelength surface wave promising for photonic integration, always suffers from the large metallic loss that seriously restricts its practical application. Here, we propose a compact SPP amplifier based on a nonlinear hybrid waveguide(a combination of silver, LiNbO_3, and SiO_2), where a couple of Bragg gratings are introduced in the waveguide to construct a cavity. This special waveguide is demonstrated to support a highly localized SPP-like hybrid mode and a low loss waveguide-like hybrid mode. To provide a large nonlinear gain, a pumping wave input from the LiNbO_3 waveguide is designed to resonate inside the cavity and satisfy the cavity phase matching to fulfill the optical parametric amplification(OPA) of the SPP signal. Proper periods of gratings and the cavity length are chosen to satisfy the impedance matching condition to ensure the high input efficiency of the pump wave from the outside into the cavity. In theoretical calculations, this device demonstrates a high performance in a very compact scheme(~3.32 μm) and a much lower pumping power for OPA compared with single-pass pumping. To obtain a comprehensive insight into this cavity OPA, the influences of the pumping power, cavity length, and the initial phase are discussed in detail.