光子晶体传感器对溶液折射率和浓度的测量

为了得出光子晶体缺陷透射峰位置与溶液折射率及溶液浓度的关系,从而得知溶液的折射率和溶度之间的关系。本文构造了(AB)~NC(AB)~N型的一维光子晶体模型,采用时域有限差分法对该一维光子晶体的透射光谱做了数值模拟和分析。结果表明,蔗糖溶液折射率和浓度与光子晶体透过峰位置之间为严格的线性关系,光子晶体缺陷模透射峰位置随溶液浓度百分比的改变而变化。该溶液测量方法的溶液折射率测量灵敏度高达498.087 nm/RIU。这为光子晶体溶液折射率及浓度测量传感器的设计制作提供了参考,有助于该溶液浓度检测传感器在实际应用中的推广。     

带多孔硅表面缺陷腔的半无限光子晶体Tamm态及其折射率传感机理

结合表面缺陷半无限光子晶体Tamm态与多孔硅光学传感机理,在光子晶体表面缺陷腔中引入多孔硅,并利用其高效的承载机制,提出基于多孔硅表面缺陷光子晶体Tamm态的折射率传感结构.在半无限光子晶体中缺陷腔与原来的周期性分层介质结构的界面上存在Tamm态,通过入射角度调制使其在缺陷腔中实现多次全反射,并在缺陷腔中加入吸收介质,使谐振波长在缺陷腔中完成衰荡,从而在反射谱中得到缺陷峰;调整光子晶体参数,使缺陷峰的半高全宽得到优化,提高其品质因数(Q值);在此基础上,根据Goos-H?nchen相位移与谐振波长的关系,建立由待测样本折射率改变所导致的多孔硅表面吸附层有效折射率变化与缺陷峰值波长漂移之间的关系模型,并分析其折射率传感特性.结果表明,此生物传感结构Q值为1429,灵敏度为546.67 nm/RIU,证明了该传感结构的有效性,可为高Q值和高灵敏度折射率传感器的设计提供一定的理论参考.     

基于倏逝波谐振的空气栅光子晶体F-P腔折射率传感特性研究

基于倏逝波理论和光学谐振原理,研究了倏逝波在光子晶体中的存在形式及空气栅光子晶体F-P腔的折射率传感机理,并建立谐振波长与待测气体折射率的关系模型。当入射光以大于全反射临界角的角度入射到光子晶体中,由于倏逝波的作用,在中心介质层形成F-P腔并产生谐振,电磁场被局部增强,与待测气体充分作用,从而使该传感结构对待测气体的折射率具有较高的敏感性。利用传输矩阵理论进行数值模拟,结果表明,折射率传感的Q值可达3447.0,灵敏度可达1260.0 nm/RIU,证明该光子晶体F-P腔折射率传感结构具有很好的传感特性,可为高精度气体折射率传感器的设计与应用提供一定的理论参考。     

一种基于模间干涉的亚波长直径光纤气体折射率传感

设计了一种基于模间干涉的亚波长直径光纤气体折射率传感方案,并分析了其测量灵敏度.将标准单模光纤和一段仅传输基模与二阶模的无包层亚波长直径光纤结合形成传感头,通过分析传感头外气体折射率的变化对两个模式干涉谱峰值移动的影响,研究了这种传感器的折射率测量灵敏度.结果表明,这种传感器的灵敏度高于利用折射率引导型光子晶体光纤的基于模间干涉的折射率传感器.因为没有气体向微孔扩散的过程,这种基于模间干涉的亚波长光纤折射率传感器可用于实时探测.     

一种基于模间干涉的亚波长直径光纤气体折射率传感

设计了一种基于模间干涉的亚波长直径光纤气体折射率传感方案,并分析了其测量灵敏度.将标准单模光纤和一段仅传输基模与二阶模的无包层亚波长直径光纤结合形成传感头,通过分析传感头外气体折射率的变化对两个模式干涉谱峰值移动的影响,研究了这种传感器的折射率测量灵敏度.结果表明,这种传感器的灵敏度高于利用折射率引导型光子晶体光纤的基于模间干涉的折射率传感器.因为没有气体向微孔扩散的过程,这种基于模间干涉的亚波长光纤折射率传感器可用于实时探测.     

含缺陷平板光子晶体十字波导传输特性研究

提出一种在光子晶体十字波导中加入点阵缺陷的特殊结构波导.采用时域有限差分法(FDTD)对该结构的导波特性进行数值模拟,计算结果表明:含缺陷结构的光子晶体波导的透射光谱较不含缺陷结构光子晶体波导的透射光谱带宽变得更窄,此结构具有窄带滤波作用.当改变波导中缺陷结构折射率取值时,该波导透射光的中心频率随缺陷介质折射率的增大而线性减小.改变中心缺陷介质柱直径时,该波导透射光波中心频率随介质柱直径的增大也呈逐渐减小趋势.这种光子晶体十字波导可作为一种窄带滤波器、分光器和可调式选频器等器件,具有一定的应用前景.     

光子晶体异质结耦合波导光开关

以二维三角晶格光子晶体为研究对象,在该光子晶体中引入两行平行的单模线缺陷波导,以一行耦合介质柱为间距,通过调节部分耦合介质柱的折射率,构筑了光子晶体异质结耦合波导光开关结构。利用平面波展开法和定向耦合原理计算了在不同入射光频率下,缺陷波导间耦合介质柱的折射率不同时的耦合长度,确定了合适的光子晶体异质结耦合波导光开关的结构参数。利用时域有限差分法研究了该光开关中耦合介质柱的折射率变化及异质结构介质柱的位置分布对光信号输出路径的影响。结果表明,通过改变该结构中耦合介质柱的折射率可以改变光的输出路径,可实现光的开关行为。并且异质结构介质柱位置的随机分布对该光开关的影响不大,有助于光子晶体新型滤波器、定向耦合器、波分复用器以及光开关等光子器件的研究。     

一种基于光子晶体异质结构的新型多通道波分复用器

在二维三角光子晶体环形腔的周围增加六个散射介质柱,构成一个新的环形腔结构,该结构使光波的透射率达到90%,带宽也比较小。通过改变光子晶体介质柱的折射率,使环形腔的选择波长不断改变,能够明显地区分出两个不同波长,且分波波长在通信波长范围之内。将不同折射材料的光子晶体连接在一起,构成一种新的光子晶体波分复用器,相比同种材料,它具有高效率,多波长选择的优点。利用这种异质结构可以构建一个多波长的波分复用结构,它也为制作多通道波分复用器奠定了基础。     

温度对液晶填充光子晶体光纤传输特性的影响

利用液晶的折射率是温度和波长函数的特性,在光子晶体光纤(PCF)芯区的空气柱中填充向列相液晶,通过改变温度来改变液晶的折射率,构成了一种温度凋制光子晶体光纤.用阶跃有效折射率模型研究了温度对这种光子晶体光纤在不同光波长时传输特性的影响,并进行了数值计算.结果表明液晶填充使光子晶体光纤的色散减小,由于折射率对温度和波长变化敏感,改变温度可以使光纤在长波长区域出现单模传输,在短波长时不会出现单模传输,即使包层相对孔径很小也不会出现无截止单模传输.温度升高使光纤的色散值增大,零色散波长向短波长方向移动.这些特性对温度调制光子晶体光纤器件的设计和应用具有一定的参考意义.     

基于表面等离子体共振和定向耦合的D形光子晶体光纤折射率和温度传感器

利用光子晶体光纤结构的灵活性和性能的优越性, 设计了一种基于D形光子晶体光纤的折射率和温度传感器. 在D形光子晶体光纤表面抛磨并镀上金纳米薄膜, 作为表面等离子体共振传感通道用来测量液体折射率; 在包层的一个空气孔中填充温敏液体甲苯, 作为定向耦合通道实现对温度的测量. 进一步的数值计算发现, 基于定向耦合效应的温度传感和基于表面等离子体共振的折射率传感相互独立, D形光子晶体光纤同时进行折射率和温度传感检测. 在各向异性的完美匹配层边界条件下利用全矢量有限元法对该传感器特性进行了数值研究, 发现D形光子晶体光纤的空气孔直径决定了定向耦合吸收峰的中心波长和温度传感的灵敏度, 金薄膜的厚度和D形结构的抛磨深度仅影响表面等离子体共振峰的相对强度. 结果表明: 该传感器在-10–80 ℃的温度范围内具有11.6 nm/℃的温度灵敏度, 在1.34–1.44折射率范围内折射率灵敏度最高可达26000 nm/RIU.     

High sensitivity and ultra-compact optical biosensor for detection of UREA concentration

In this paper, we suggest two-dimensional photonic crystal based biosensors for measurement of urea concentration in urine by means of refractive index detecting. In case of variation of urea concentration in urine, both the output peak intensity and the resonant peak center wavelength will shift. Two different structure dimensions are used to analyze the sensing characteristics of urine. The first sensor consists of a novel square ring joined to a simple waveguide with rods in air configuration. The second sensor is schemed by use of two-dimensional photonic crystals based on air hole in slab with elliptical resonant cavity in the middle of a photonic crystal waveguide. To realize sensing in both cases, we fill air area by urine sample. A high sensitivity is observed in small structures. In addition, we demonstrated a high quality factor, which is superior to those reported in recently published work discussing urine components based on photonic crystal, with small size sensors and fast response times.     

基于低双折射光子晶体光纤Sagnac干涉仪的超低温度系数扭曲传感器

研究了低双折射光子晶体光纤中由光纤扭曲造成的圆双折射效应,并应用Sagnac干涉仪结构设计了扭曲传感器.在Sagnac环中的光子晶体光纤上施加机械压力引入初始线双折射并产生正弦干涉光谱,再扭曲光纤产生圆双折射使干涉光谱随扭曲角度移动.光谱峰值波长随扭曲角度变化符合Sinc函数关系,理论分析与实验相符.传感器灵敏度为1....     

Photonic crystal fiber tip interferometer for refractive index sensing

In this paper we present an interferometer based on photonic crystal fiber (PCF) tip ended with a solid silica-sphere for refractive index sensing. The sensor is fabricated by splicing one end of the holey PCF to a single mode fiber (SMF) and applying arc at the other end to form a solid sphere. The sensor has been experimentally tested for refractive index and temperature sensing by monitoring its wavelength shift. Measurement results show that the sensor has the resolution of the order of 8.7×10(-4) over the refractive index range of 1.33-1.40, and temperature sensitivity of the order of 10 pm/°C in the range of 20-100 °C.     

基于低双折射光子晶体光纤Sagnac干涉仪的超低温度系数扭曲传感器

研究了低双折射光子晶体光纤中由光纤扭曲造成的圆双折射效应,并应用Sagnac干涉仪结构设计了扭曲传感器.在Sagnac环中的光子晶体光纤上施加机械压力引入初始线双折射并产生正弦干涉光谱,再扭曲光纤产生圆双折射使干涉光谱随扭曲角度移动.光谱峰值波长随扭曲角度变化符合Sinc函数关系,理论分析与实验相符.传感器灵敏度为1.00 nm/°,分比率为0.01°,并具有超低的温度系数-0.5 pm/℃.     

基于椭球封闭空气腔的光纤复合法布里-珀罗结构折射率传感特性研究

提出了基于微椭球型空气腔的在线型光纤复合法布里-珀罗干涉结构,并对其折射率传感特性进行了研究.椭球型空气微腔是利用光纤熔接机对实芯光子晶体光纤和单模光纤以特定的熔接参数熔接形成.用高斯光束模型和ABCD法则分析了椭球型空气腔的腔内损耗,建立了电磁场在复合法布里-珀罗干涉结构中传播的物理模型.根据腔长比值的不同,环境折射率对干涉条纹的影响有对比度调制和波长调制,主要研究了一种波长调制型复合法布里-珀罗结构折射率传感器.仿真结果表明该折射率传感器在1—1.6范围内不出现折射率转折点;实验结果表明在1.333—1.466范围内,折射率灵敏度～37.088 nm·RIU-1,分辨率约为2.69×10-5.该光纤复合法布里-珀罗结构干涉条纹对比度高、体积小、成本低,用于折射率测量可靠性高、分辨率高、无折射率拐点、温度串扰小.     

Ultracompact biochemical sensor built with two-dimensional photonic crystal microcavity

We report an experimental demonstration of an ultracompact biochemical sensor based on a two-dimensional photonic crystal microcavity. The microcavity, fabricated on a silicon-on-insulator substrate, is designed to have a resonant wavelength (lambda) near 1.5 microm. The transmission spectrum of the sensor is measured with different ambient refractive indices ranging from n = 1.0 to n = 1.5. From observation of the shift in resonant wavelength, a change in ambient refractive index of delta(n) = 0.002 is readily apparent. The correspondence between absolute refractive index and resonant wavelength agrees with numerical calculation to within 4% accuracy. The evaporation of water in a 5% glycerol mixture is also used to demonstrate the capability for in situ time-resolved sensing.     

Fiber in-line Mach-Zehnder interferometer constructed by selective infiltration of two air holes in photonic crystal fiber

A fiber in-line Mach-Zehnder interferometer is fabricated through selective infiltrating of two adjacent air holes of the innermost layer in the solid core photonic crystal fiber, assisted by femtosecond laser micromachining. The liquid infiltrated has higher refractive index than that of the background silica, and, hence, the two rods created can support a guide mode with lower effective refractive index than that of silica. The interference is produced by the fiber fundamental mode and the guide mode. The free spectral range (FSR) of the interferometer is found to be dependent on the photonic crystal fiber length, and a large FSR corresponds to a short photonic crystal fiber length. Such an interferometer device is robust and exhibits extremely high temperature sensitivity (～7.3?nm/°C for the photonic crystal fiber length of 3.4?cm) and flexible operation capability.     

Modeling a sensitive pressure and temperature sensor using rectangular PCF by 2-D FDTD technique

We propose a sensitive pressure and temperature sensor depends on hollow core rectangular photonic crystal fiber. The proposed modeling is carried out by implementing 2-D finite difference time domain (FDTD) method. The two parameters like pressure and temperature plays a vital role in reservoir engineering to increase the production rates of oil well and our sensor technique is depend on the transmission peak wavelength shift which is caused by temperature/pressure change, and geometrical parameter of the structure of rectangular PCF. Here we have done simulation for various work using 2-D FDTD method application to sensing. We have shown the proposed design which provides the sensitivity with linear dependence of the resonance wavelength over refractive index of PCF holes at a operating wavelength of 1.55 μm.     

A cascaded photonic crystal fiber Mach–Zehnder interferometer formed by extra electric arc discharges

In this paper, a cascaded Mach–Zehnder interferometer based on a photonic crystal fiber is reported. It is demonstrated that by applying a small dose of extra arc discharge to the photonic crystal fiber sensing part which is spliced to lead-in and lead-out single-mode fibers with core offset, the in-line Mach–Zehnder interferometer could be simply cascaded. From the analysis of Fourier transformed spatial spectra and the response tests as a sensor, it is shown that such a cascaded interferometer could effectively broaden the utilizable spectral shift range for a measured value.