迈克尔逊干涉仪测波长的一种便捷方法

提出了迈克尔逊干涉仪测波长的一种便捷且精确的测量方法。利用自制的光电计数及电机控制装置,在短时间内无须任何数据处理便可由计数器直接读取待测光源波长值。该方法不仅实现了条纹的全自动计数,又简化了干涉仪繁复的读数环节,更消除了仪器的零点误差。     

An investigation on optical microfiber reflector with low reflectance

The backscattering characteristics of optical microfiber(OM) are experimentally studied by controlling heating temperature and cooling method during the OM fabrication process.OM samples with various reflectances from 0.1% to 1% are achieved.An OM with waist length of 5 mm,waist diameter of 1 μm,and approximately 0.5% reflectance is used as the end reflector of a fiber Fabry-Perol(F-P) interferometer.A piezoelectric ceramic transducer(PZT) fiber phase modulator is used to test the sensing performance of the fiber F-P interferometer.Experimental results verify that the OM with low reflectance can be used as a reflector in the F-P interferometer.     

Optical microfiber phase modulator directly driven with low-power light

An optical microfiber phase modulator （OMPM） directly driven with low-power light is presented. Phase modulation response of OMPM is theoretically analyzed. A 10-mm optical microfiber （OM）, tapered from conventional single-mode fiber, is inserted in one arm of a Michelson fiber interferometer. To drive the OMPM, 980-nm wavelength light with sinusoidal intensity modulation is injected into the interferometer. The OMPM response properties are measured and π-phase modulation amplitude can be obtained with only 7.5-mW average power light at 1-kHz modulation frequency. The OMPMs shown in this study have advantages of simple structure, potential compact size, and low-power-driven light.     

Superconducting quantum interference devices with different damped junctions operated in directly coupled current- and voltage-bias modes

We investigate niobium thin film superconducting quantum interference devices （SQUIDs） with different Steward- McCumber parameters βc operated in both current- and voltage-bias modes. We experimentally prove that there is no difference between the two bias modes with respect to the SQUID intrinsic noise and the noise contribution from the preamplifier. Furthermore, the relationships of the SQUID dynamic parameters, （Rd）current bias ≈ （Rd）voltage bias and （σV/σФ）current bias ≈ [σi/σФ）Rd]voltage bias, are always satisfied. For a strongly damped SQUID withβc ≈ 0.25, addi- tional positive feedback （APF） and noise cancellation （NC） were employed to enhance σV/σФ, the former showing a degradation in the linear flux range but otherwise the same with NC. For a weakly damped SQUID with βc ≈ 3, it is di- rectly connected to the preamplifier without APF or NC, and a low SQUID system noise of about 4μФ0/x/Hz is measured, which is close to its intrinsic noise.     

Non-contact angle measurement based on parallel multiplex laser feedback interferometry

We present a novel precise angle measurement scheme based on parallel multiplex laser feedback interferometry （PLFI）, which outputs two parallel laser beams and thus their displacement difference reflects the angle variation of the target. Due to its ultrahigh sensitivity to the feedback light, PLFI realizes the direct non-contact measurement of non- cooperative targets. Experimental results show that PLFI has an accuracy of 8＂ within a range of 1400＂. The yaw of a guide is also measured and the experimental results agree with those of the dual-frequency laser interferometer Agilent 5529A.     

基于纤芯失配型马赫曾德尔光纤折射率和温度同时测量传感器的研究

设计和制作了一种基于单模多模细芯单模光纤马赫曾德尔(Mach-Zehnder)干涉仪结构,可同时测量折射率和温度的传感器。该传感器中,多模光纤和细芯单模熔接点充当光耦合器。导入光纤中传输的光经多模光纤后在细芯光纤的纤芯和包层中激发出纤芯模和包层模,不同模式光在细芯光纤中传输时将产生光程差,再经细芯单模熔接点耦合成为导出光纤的纤芯模而干涉。传感器透射光谱随着环境折射率和温度的变化发生漂移,通过监测不同级次的干涉谷可实现折射率和温度的同时测量。通过对传感器的透射光谱进行傅里叶变换分析可知该透射光谱主要由LP01模和LP16模干涉形成。该传感器透射光谱中1535nm附近干涉谷的折射率和温度响应灵敏度的理论值分别为-55.90nm/RIU和0.0501nm/℃(其中RIU为折射率单位);1545nm附近干涉谷的折射率和温度响应灵敏度的理论值分别为-56.26nm/RIU和0.0505nm/℃。在折射率和温度的变化范围分别为1.3449~1.3972和20℃~90℃的环境中对传感器的响应特性进行实验研究,结果表明:透射光谱中1535nm附近干涉谷的折射率和温度响应灵敏度分别为-53.03nm/RIU和0.0465nm/℃;1545nm附近干涉谷的折射率和温度响应灵敏度分别为-54.24nm/RIU和0.0542nm/℃。理论分析与实验结果相一致。该传感器在生物医学领域有较好的应用前景。     

基于光纤法布里-珀罗干涉仪的高压静电传感器

静电电压表对测量交直流高压有着非常重要的作用。为了实现高电压静电电压表的精确测量,提出并制备了一种采用法布里珀罗(FP)腔干涉原理的静电电压传感器。所设计的传感器电极与高压电极构成一组静电电压测量电极,此传感器的FP腔由光纤准直器和外侧镀铝的聚酯膜构成,当在高压电极施加载荷时,聚酯膜与高压电极之间产生均匀电场,在电场力作用下聚酯膜产生形变,从而改变FP腔的腔长,造成FP传感器的输出光谱偏移,采用相位解调法获得高压电极上施加的载荷,实现电压的静电测量。实验结果表明:可实现5~16kV直流高压和交流高压有效值的测量,5~10kV范围测量精度为1.21%,10~16kV的测量精度为0.61%。此传感器满足高电压的测量要求。     

平行耦合双量子点分子A-B干涉仪的电荷及其自旋输运

利用非平衡格林函数方法,理论研究每臂中嵌有一个平行耦合双量子点分子的A-B干涉仪(平行耦合双量子点分子A-B干涉仪)的电荷及其自旋输运性质.无外磁场时,与每臂中嵌有一个量子点的A-B干涉仪相比较,平行耦合双量子点分子A-B干涉仪中电子隧穿变得更加容易发生.当平行耦合双量子点分子A-B干涉仪中引入外磁场时,能够在电导能谱中观察到一个Fano共振和一个反共振,这两种输运状态在磁场取适当数值时能够同时消失.此外,通过调节左右两电极间的偏压、磁通和Rashba自旋轨道相互作用,可以对体系自旋输运进行调控.     

成像型速度干涉仪散斑成因的研究

在冲击波过程中,利用成像型速度干涉仪探测样品自由面的速度时,散斑的叠加使得干涉曲线被严重干扰,影响了速度信息的精密提取。在理论上从光路的角度分析了系统中可能造成散斑的两种因素:靶面粗糙度和多模光纤。在实验上设计了三种照明方式分别对这两种因素进行验证。离线实验的结果表明,多模光纤的引入对散斑的产生起了主要的作用,这对抑制乃至遏制散斑的产生具有很好的指导性意义。     

低功耗聚合物Mach-Zehnder热光开关

采用传统的半导体工艺制作了聚合物Mach-Zehnder型热光开关.利用扫描电镜观测波导形貌,通过红外摄像机观测波导的近场输出光斑,在通信波段1 550 nm波长下测试了器件的输出光谱.在电极上施加直流信号,测得热光开关的消光比为－15 dB,驱动功率为16 mW.引入直流偏置网络,获得了器件的开关特性曲线,经测量开关上升时间为1.2 ms,下降时间为0.8 ms.