用于全光铯原子磁力仪的激光器稳频技术研究

全光铯原子磁力仪是采用光学的方法实现微弱磁场检测,激光频率稳定性直接影响磁力仪的灵敏度。分析了二向色性原子蒸气激光频率锁定(Dichroic atomic vapor laser lock DAVLL)技术用于稳定激光器频率的原理,及其在全光原子磁力仪中的应用优势,发现通常的二能级原子模型不适用于分析铯原子D2线的稳频。实验测量了不同磁场下铯原子D2线基态Fg=4和Fg=3跃迁的DAVLL光谱,发现16mT是实现DAVLL稳频的最佳磁场;在此磁场附近,基态Fg=4跃迁鉴频曲线零点相对于Fg=4→Fe=5跃迁会产生6MHz/mT的线性频移,基态Fg=3跃迁鉴频曲线零点相对于Fg=3→Fe=4线会产生-9MHz/mT的线性频移。     

双波长外腔共振和频中Boyd-Kleinman因子优化的理论研究

双波长外腔共振是提高和频转换效率的有效手段,然而基于Boyd-Kleinman(BK)理论,和频效率除了受基频光功率密度影响外,主要受BK因子限制。本文通过分析BK因子随腔结构参数的变化关系,给出基于外腔频率转换过程中BK因子优化的一般方案,从而为搭建相关实验提供必要的理论基础。     

基于声共振原理的管道长度测量仪

利用平面声波在管内形成驻波,根据管口声阻抗公式推导了驻波发生时相邻共振频率之差与管道长度的定量关系,利用自制装置实现了管道(直管、弯管)长度的测量,测量误差均在1.5%以下.     

超声波专题设计性实验

在测量超声波在空气中传播速度实验基础上,开设了超声波专题设计性实验,分别增加了测量压电换能器的共振频率、超声波在空气中的损耗系数、超声波在水中的传播速度等实验内容,丰富了大学物理实验教学内容,拓展了学生视野.     

浅谈杯鼓实验中空气柱的选频作用

本文首先通过杯鼓实验得到了不同空气柱长度下杯内声波的频域图,然后基于波动理论解析分析了边界振动有衰减时空气柱的共振频率及振幅,结果表明空气柱长度在声波传播过程中具有明显的选频作用。     

关于激光模谱分析实验模式图的讨论

对近代物理实验中激光模谱分析实验激光模式图的具体表示形式及所表达的物理含义进行了分析及讨论.     

Improving microwave dielectric properties of La2.98/3Sr0.01(Mg0.5Sn0.5)O3 ceramics with CuO additive

The microwave dielectric properties of CuO-doped La_2.98/3Sr_0.01(Mg_0.5Sn_0.5)O₃ ceramics were investigated with a view to their application in microwave devices. CuO-doped La_2.98/3Sr_0.01(Mg_0.5Sn_0.5)O₃ ceramics were prepared by the conventional solid-state method. The X-ray diffraction patterns of CuO-doped La_2.98/3Sr_0.01(Mg_0.5Sn_0.5)O₃ ceramics exhibited no significant variation of phase with sintering temperature. By adding 0.75 wt.% CuO, a dielectric constant of 20.07, a quality factor (Q × f) of 63,000 GHz, and a temperature coefficient of resonant frequency τ_f (−77.0 ppm/°C) were obtained when La_2.98/3Sr_0.01(Mg_0.5Sn_0.5)O₃ ceramics were sintered at 1500 °C for 4 h.     

Dual-band frequency selective surface with quasi-elliptic bandpass response

Based on the substrate integrated waveguide technology,we present a dual-band frequency selective surface(FSS) with a quasi-elliptic bandpass response.The characteristics of the quasi-elliptic bandpass response are realized by shunting two substrate integrated waveguide cavities of different sizes,with the same slots on both sides of the metal surfaces.Four cavities of different sizes and two slots of different sizes are used to design the novel FSS.Every bandpass response with sharp sidebands is induced by two transmission nulls that are generated by the coupling between the slot aperture resonance and the cavity resonance.The simulation results show that such dual-band FSS has the advantages of high selectivity and stable performance at different oblique incident angles.Moreover,it is easy to fabricate.     

Properties and characteristics of P(VDF/TrFE) transducers manufactured by a solution casting method for use in the MHz-range ultrasound in air

Highly effective piezoelectric polymer transducers operating in air at high frequencies have been successfully made by casting a solution of ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) P(VDF/TrFE) directly on a backing metal plate, and their performance has been evaluated. By utilizing this method, it has been possible to develop the three kinds of transducers that operate respectively at 4, 6 and 10 MHz in air. For precise evaluation of the performance of the P(VDF/TrFE) transducers, the absorption loss in air was measured up to 10 MHz. It was confirmed that the empirical formula obtained from the measured absorption values in air at high frequencies was in alignment with its theoretical value. In addition, a high lateral resolution acoustic image of a ROM-Chip (amplitude-image) at 6 MHz in air was successfully displayed using an air coupled concave type P(VDF/TrFE) transducer by bonding an epoxy adhesive.