Author Affiliations
Abstract
We investigate the optical bistability (OB) in a duplicated two-level system contained in a ring cavity. The atoms are driven by two orthogonally polarized fields with a relative phase. The OB behavior of such a system can be controlled by the amplitude and the relative phase of the coupling field, and it is possible to switch between bistability and multistability by adjusting the relative phase.
020.1670 Coherent optical effects 190.1450 Bistability Chinese Optics Letters
2013, 11(5): 050201
Author Affiliations
Abstract
A micro Fabry-Perot interferometer (M-FPI) is constructed by splicing a short section of polarization-maintaining photonic crystal fiber (PM-PCF) to an end-cleaved single-mode fiber with controllable offset. Due to the high effective optical path difference induced by the solid core of the PCF, the M-FPI has an ultrasmall cavity of approximately 110 \mu m. The temperature sensitivity within a range from 33 oC to approximately 600 oC is measured to be 13.8 pm/oC, which shows good agreement with the theoretical result. This proposed sensor has the advantages of ultracompact size and high stability. Therefore, it is suitable for various space-limited sensing applications in harsh environments.
060.0060 Fiber optics and optical communications 060.2310 Fiber optics 060.2370 Fiber optics sensors 060.2430 Fibers, single-mode Chinese Optics Letters
2012, 10(7): 070607
Author Affiliations
Abstract
A simple fiber tip sensor for refractive index (RI) measurement based on Fabry–Perot (FP) interference modulated by Fresnel reflection is proposed and demonstrated. The sensor head consists of an etching-induced micro air gap near the tip of a single-mode fiber. The microgap and the fiber tip function as two reflectors to form a FP cavity. The external RI can be unambiguously measured by monitoring the fringe contrast of the interference pattern from the reflection spectrum. The experimental results show that the proposed sensor achieves temperature-independent RI measurement with good linear response. The proposed sensor achieves a high RI resolution of up to 3.4 \times 10 5 and has advantages of low cost and easy fabrication.
060.2370 Fiber optics sensors 120.2230 Fabry-Perot Chinese Optics Letters
2012, 10(5): 050603
Author Affiliations
Abstract
A novel all-fiber temperature-calibrated refractometer based on a compact fiber Bragg grating (FBG) single–multi–single (SMS) structure is proposed and experimentally demonstrated. The sensor head is composed of a FBG combined with a SMS structure, in which the middle multimode fiber (MMF) section is etched by a time-controlled hydrofluoric. The transmission dip of SMS is extremely sensitive to ambient refractive index (RI) variation, whereas the upstream FBG provides the necessary temperature information for RI calibration. All aforementioned functions are performed via a compact FBG-SMS structure not longer than 25 mm. The proposed sensing device provides a linear RI sensitivity over water or waterbased solutions (RI values near 1.33 at optical wavelengths for most biological and many environmental applications), and has temperature-calibration capability. Hence, the said refractometer is a good candidate for sensing in chemical and biological applications.
060.2370 Fiber optics sensors 060.3735 Fiber Bragg gratings Chinese Optics Letters
2012, 10(3): 030604
Author Affiliations
Abstract
1 Department of Physics, Northwest University of China, Xi'an 710069, China
2 Key Laboratory of Photoelectricity Gas-Oil Logging and Detecting, Ministry of Education, Xi'an Shiyou University of China, Xi'an 710065, China
A compact fiber Bragg grating (FBG) diaphragm accelerometer based on L-shaped rigid cantilever beam is proposed and experimentally demonstrated. The sensing system is based on the integration of a flat diaphragm and an L-shaped rigid cantilever beam. The FBG is pre-tensioned and the two side points are fixed, efficiently avoiding the unwanted chirp effect of grating. Dynamic vibration measurement shows that the proposed FBG diaphragm accelerometer provides a wide frequency response range (0–110 Hz) and an extremely high sensitivity (106.5 pm/g), indentifying it as a good candidate for embedding structural health monitoring and seismic wave measurement.
光纤布拉格光栅 振动传感器 膜片加速度计 060.2370 Fiber optics sensors 060.3735 Fiber Bragg gratings 280.4788 Optical sensing and sensors Chinese Optics Letters
2011, 9(10): 100604
Author Affiliations
Abstract
Department of Physics, Northwest University of China, Xi'an 710069, China
A metal bellows-based fiber Bragg grating (FBG) accelerometer is proposed and experimentally demonstrated. The optical fiber (containing the FBG) is pre-tensioned, and the two ends of the optical fiber are fixed directly from the shell to the inertial mass. In this design, the FBG is uniformly tensioned to obtain a constant strain distribution over it. By employing this configuration, the FBG always has a sharp reflection characteristic with no broadening in its reflection spectrum during wavelength shifting. Dynamic vibration measurements show that the proposed FBG accelerometer has a wide frequency response range (5–110 Hz) and an extremely high sensitivity (548.7 pm/g). The two important indicators of FBG accelerometer can be tuned by the addition of mass to tailor the sensor performance to specific applications, identifying it as a good candidate for structural health monitoring.
光纤光栅 金属波纹管 加速度传感器 060.2370 Fiber optics sensors 230.1480 Bragg reflectors 050.2770 Gratings Chinese Optics Letters
2011, 9(9): 090606
Author Affiliations
Abstract
Department of Physics, Northwest University of China, Xi'an 710069, China
The intelligent structural health monitoring method, which uses a fiber Bragg grating (FBG) sensor, is a new approach in the field of civil engineering. However, it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements. In this letter, a flextensional FBG-based accelerometer is proposed and demonstrated. The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz, with a high sensitivity of 410.7 pm/g. In addition, it has a broad and flat response over low frequencies ranging from 1 to 10 Hz. The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications. Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer. These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.
光纤光栅 加速度计 弯曲伸张弹性结构 低频振动 060.2370 Fiber optics sensors 230.1480 Bragg reflectors 050.2770 Gratings Chinese Optics Letters
2011, 9(9): 090607
1 西北大学物理学系, 陕西 西安 710069
2 榆林学院物理与电气工程系, 陕西 榆林 719000
3 西北大学光子学与光子技术研究所暨陕西省光电子省级重点开放实验室, 陕西 西安 710069
4 西北大学信息科学与技术学院, 陕西 西安 710069
研制一台激光二极管(LD)侧面抽运双棒串接准连续Nd∶YAG折叠腔高功率绿光激光器,理论分析了热致双折射效应对系统的影响,并对用石英旋转片补偿前后的情况进行模拟对比。在考虑了补偿后的情况下设计了热稳定谐振腔。实验中采用两个串接的由30个20 W的LD阵列侧面抽运的Nd∶YAG棒和Ⅱ类临界相位匹配HGTR-KTP晶体,在抽运电流均为21.6 A,重复频率为27.2 kHz时,获得了最大平均输出功率为164 W,脉冲宽度为130 ns的532 nm绿光输出,光-光转换效率为13.7%,测得光束质量因子为M2x=9.52, M2y=9.86,不稳定度为2.3%。实验结果显示,经补偿后的激光系统能在宽的稳区范围内稳定运转。
激光器 高功率 热致双折射效应 532 nm绿光
为扩大数字全息的测量视场,使数字全息可以应用于大物体三维形貌的测量,利用菲涅耳离轴数字全息,让照明光依次照明物体的各个区域并分别记录全息图,利用精密电控旋转台精确控制参考光的入射角以保证每次记录时物参角不变,通过参考光入射角的变化量确定物体不同被照明区域之间的位置关系,对获得的物体去包裹的相位图进行拼接,进而得到整个物体的三维形貌。利用该方法测量了大小为11 cm×19 cm的石膏嘴的三维形貌,图像拼接的绝对拼接误差远小于1.14 mm,高度测量误差约为0.5 mm,实验结果说明这种测量方法能够有效地扩大数字全息测量物体三维形貌的视场并且具有和横向分辨率相当的拼接精度。
信息光学 形貌测量 数字全息 图像拼接 视场