增光子二模纠缠相干态的纠缠特性及其通过腔量子电动力学的制备

分析了增光子二模纠缠相干态的纠缠特性,得到共生纠缠度的解析表示式.结果表明:增光子二模纠缠相干态的共生纠缠度与叠加态的相位有非常灵敏的关系.提出了一种制备增光子相干态和增光子二模纠缠相干态的方法,其制备过程为首先把增光子相干态转化为相干态与真空态一种特殊的叠加态(叠加系数与相干态振幅有关),再通过位于高Q腔内的原子与经典激光场的相互作用,从而实现增光子相干态的制备.通过一个飞行原子先后与两个光腔中光场相互作用可以实现增光子二模纠缠相干态的制备.     

High-power near diffraction-limited 1 064-nm Nd:YAG rod laser and second harmonic generation by intracavity-frequency-doubling

We present a near diffraction-limited 1 064-nm Nd:YAG rod laser with output power of 82.3 W(M~2≈1.38). The power fluctuation over two hours is better than±1.1%.Pulsed 1064-nm laser with an average power of 66.6 W and pulse width of 46 ns are achieved when the laser is Q-switched at a repetition rate of 10 kHz.The short pulse duration stems from the short cavity as well as the high-gain laser modules. Using intracavity-frequency-doubling,a 35.0-W near diffraction-limited 532-nm green laser(M~2≈1.32) is achieved with a pulse width of 43 ns.     

Polarization-locked VCSEL with PM fiber pigtail for quantum communication

Quantum communication is a new technology requiring a stable and reliable laser source for communication security. A new kind of polarization-locked vertical-cavity surface-emitting laser (VCSEL) with polarization maintaining (PM) fiber pigtail is fabricated as a decoy state laser source. The VCSEL is packaged in a standard butterfly box integrated with thermoelectric coder (TEC) and thermistor. The optical pulse width of full-width at half-maximum (FWHM) is smaller than 400 ps with a 100-MHz on/off modulation frequency. The results reveal that modulation range is better than 4. Moreover, the polarization is stable, and the power extinction ratio is larger than 25. The center wavelength is 850 nm, and the SMSR is better than 40 dB.     

利用腔电光力系统提高罗兰C授时能力研究

罗兰C系统受原子钟以及经典无线电信号测量精度的影响,难以为用户提供高精度授时.提出了一种基于杂化微波-光纠缠的罗兰C系统授时方案,通过腔电光力转换器制备纠缠微波-光信号,并利用纠缠信号的二阶相干函数得到信号传播时间,根据授时时序关系修正用户本地钟时刻并完成授时.仿真分析了腔电光力转换器的参数对授时精度的影响.所提方案在理论上实现了对罗兰C系统授时精度的提高,在抗压制干扰、欺骗干扰等方面都具有一定优势.     

Casimir Force in a One-Dimensional Cavity with Quasimode

We calculate the Casimir force between a perfect reflective wall and a semitransparent wall in the laser cavity. Using the Fox-Li quasimode theory to describe the electromagnetic field in the laser cavity, the vacuum energy and the Casimir force are calculated. We compare our results to the force in the ideal situation and find it smaller in the dissipative cavity. We also find that the Casimir force decreases with the increase of the wall-wall distance and the decay rate of the quasimodes in the laser cavity.     

球形腔聚焦换能器的非线性声场建模

球形腔聚焦换能器是一种特殊形式的聚焦换能器。为理论证实球形腔聚焦换能器能突破传统超声聚焦在聚焦精度和聚焦增益上的限制,采用Westervelt非线性方程并结合时域有限差分法,建立了球形腔聚焦换能器的非线性声场的数值模型。数值计算了直径为120 mm的0.6 MHz球形腔聚焦换能器的非线性声场,并与传统球壳形聚焦换能器进行了对比。当激励声压为100 kPa时,球形腔聚焦换能器与同尺寸壳形聚焦换能器相比,焦点正声压增益提高约8.5倍,且焦域精度更高,-6 dB聚焦区域在z方向减小约20倍,达到次波长尺度。研究表明球形腔聚焦换能器在高强度聚焦超声精细治疗上具有潜在的应用前景。      

通过插入Au薄膜改善绿光OLED器件的发光色纯度

在一些有机电致发光器件中,Au常被用作阳极,研究者希望Au在导电的同时兼具半透明可出光的属性,这要求Au在能导电的同时厚度要尽量薄。因此制备两种金属共同组成电极成为了选择。将半透明Au/Al层插入阳极一侧,制备了结构为ITO/Al(16 nm)/Au(10 nm)/TPD(30 nm)/AlQ(30 nm)/LiF(0.5 nm)/Al的OLED器件,相对于器件ITO/TPD(30 nm)/AlQ(30 nm)/LiF(0.5 nm)/Al在长波方向出现了光谱窄化现象,通过分析和实验判断该现象是Au薄膜特有的对光的选择透过性造成,而并非微腔效应。阳极一侧加入了Au/Al的器件保持了广视角无角度依赖的优点,同时可以输出滤掉部分红光的纯度更高的发光,发光色纯度得到了改善。     

Optomechanical sensing with on-chip microcavities

The coupling between optical and mechanical degrees of freedom has been of broad interest for a long time. However, it is only until recently, with the rapid development of optical mierocavity research, that we are able to manipulate and utilize this coupling process. When a high Q microeavity couples to a mechanical resonator, they can consolidate into an optomeehanieal system. Benefitting from the unique characteristics offered by optomeehanical coupling, this hybrid system has become a promising platform for ultrasensitive sensors to detect displacement, mass, force and acceleration. In this review, we introduce the basic physical concepts of cavity optomechanies, and describe some of the most typical experimental cavity optomechanical systems for sensing applications. Finally, we discuss the noise arising from various sources and show the potentiality of optomechanical sensing towards quantum-noise-limited detection.     

高Q光学微球腔角速度传感效应验证

根据角速度传感的基本原理,搭建了以高Q光学微球腔为核心敏感部件的角速度传感实验测试系统。实验中通过调制、解调技术得到了光学微球腔的谐振曲线及其相对应的解调曲线,并采用PID反馈控制电路实现了微球腔谐振点的实时跟踪锁定,谐振点锁定精度约为10 kHz。通过对系统提供低、高2组不同的旋转角速度进行实验测试,并对数据进行处理分析,得到系统输出信号幅度的变化趋势与测试转台提供的旋转角速度变化情况相对应的结果。初步验证了高Q光学微球腔的角速度传感效应,为后续深入研究高Q光学微谐振腔角速度传感器件奠定了基础。