石英增强光声传感技术研究进展

主要回顾了近几年石英增强光声传感技术的最新研究进展,展望了未来几年该技术的发展趋势。从石英增强光声传感技术的基本原理开始,介绍了传统的石英增强光声传感器系统的搭建,围绕如何降低系统噪声和进一步提高探测灵敏度展开论述。阐述了定制音叉式石英晶振的建模与设计,详细讨论了如何使用定制的音叉探索新型光谱测声器配置,使探测灵敏度提高两个数量级,并介绍了利用这些定制音叉的泛频振动模式实现减小声音共振腔长度的目的和双气体探测功能。最后讨论了该技术的进一步发展方向。     

驱动场失谐对Λ型原子EIT的影响

文章用缀饰原子研究电磁感应透明,为分析探测光强度的破坏性干涉提供了一个清晰的物理图象,用这种方法可更简洁地研究驱动场失谐对电磁感应透明的影响.     

低频波长调制光谱的理论与实验研究

通过调制半导体激光外腔压电陶瓷的电压实现低频波长调制 ,并慢扫描激光器的波长 ,测量了CS 原子D2线 [6S1 2 (F =4)→ 6P3 2 ]的吸收光谱 ,利用锁相放大器处理了二次、四次、六次谐波信号 ,实验结果与理论分析相吻合 ,在实验过程中还发现高次谐波探测可以有效地提高探测信号的信噪比     

Experimental investigation of the sub-Doppler transmission spectroscopy in a thin vapour layer at room temperature

The sub-Doppler transmission spectrum in a thin vapour layer (about 150 μm) was observed at room temperature using the wavelength modulation technology. The absorption signal and its second-order harmonic were detected with an external-cavity diode laser. A sub-Doppler spectrum corresponding to resonant transitions of the caesium D_2 line (6S_{1/2}→6P_{3/2}) was demonstrated. The dependence of the transmission signal on the intensity of the laser was also investigated.     

Investigation of ultracold atoms and molecules in a dark magneto-optical trap

In this paper,ultracold atoms and molecules in a dark magneto-optical trap(MOT) are studied via depumping the cesium cold atoms into the dark hyperfine ground state.The collision rate is reduced to 0.45s-1 and the density of the atoms is increased to 5.6×1011cm-3 when the fractional population of the atoms in the bright hyperfine ground state is as low as 0.15.The vibrational spectra of the ultracold cesium molecules are also studied in a standard MOT and in a dark MOT separately.The experimental results are analyzed by using the perturbative quantum approach.     

单激光源谐波遥感探测甲烷研究

提出了一种利用单一可调谐外腔二极管激光 (ECDL)及谐波探测技术对甲烷进行现场、实时遥感探测方案。通过理论推导计算出该方案在甲烷 2ν3 吸收带的R6支吸收线上理论最小可探测路径 积分浓度为 87× 10 -9。根据该方案建立了实验系统 ,实验结果验证了该方案的可行性并估算出实验最小可探测甲烷的路径 积分浓度为 4 2 0× 10 -9。     

High-resolution photoassociation spectroscopy of ultracold Cs2 long-range 0g- state：The external well potential depth

High-resolution photoassociation spectroscopy is reported using a modulation spectroscopy technology in a cesium atomic magneto-optical trap. The two lowest vibrational levels have been experimentally observed which have been theoretically predicted in [Phys. Rev. A 75 052501(2007)]. A new potential curve is obtained by using the Rydberg–Klein–Ress method with a well depth of 82.384±0.026 cm-1, which is deeper than the result of previous experiment( 77.909 cm-1) and the theoretical prediction( 81.6445 cm-1).     

The laser-intensity dependence of the photoassociation spectrum of the ultracold Cs_2(6S_(1/2) + 6P_(1/2))0_u~+ long-range molecular state

The high-resolution photoassociation spectrum of the ultracold cesium molecular 0_u~+ state below the 6S 1/2 + 6P 1/2 limit is presented in this paper. The saturation of the photoassociation scattering probability is observed from the dependence of the trap-loss probability on the photoassociation laser intensity. The corresponding resonant line width is also demonstrated to increase linearly with increasing photoassociation laser intensity. Our experimental data have good consistency with the theoretical saturation model of Bohn and Julienne Bohn J L and Julienne P S 1999 Phys. Rev. A 60 1].     

Enhancement of signal-to-noise ratio of ultracold polar NaCs molecular spectra by phase locking detection

We report a method of high-sensitively detecting the weak signal in photoassociation(PA) spectra of ultracold NaCs molecules by phase sensitive-demodulated trap-loss spectra of Na atoms from a photomultiplier tube. We find that the signal-to-noise ratio(SNR) of the PA spectra is strongly dependent on the integration time and the sensitivity of the lockin amplifier, and our results show reasonable agreement with the theoretical analyses of the SNR with the demodulation parameters. Meanwhile, we investigate the effect of the interaction time of the PA laser with the colliding Na–Cs atom pairs on the SNR of the PA spectra. The atom loss rate is dependent on both the PA-induced atom loss and the loading of the MOT. The high-sensitive detection of the excited ultracold NaCs molecules lays a solid foundation for further study of the formation and application of ultracold NaCs molecules.     

阶跃恢复二极管用于控制产生纳秒激光脉冲

给出一种利用阶跃恢复二极管(SRD)产生ns级的电子脉冲发生器,用来驱动低阻抗的激光二极管,产生纳秒激光脉冲输出.该脉冲发生器能够在偏置工作状态下产生0.1～3.0 A的脉冲,用于控制产生的激光输出脉冲宽度可以在3～10 ns内调节.