辨向激光光栅测振仪的研究

文中讨论激光多普勒技术的双相检测辨向方法,计算了单周期矩形相位光栅的衍射光强分布,比较了光栅常数相同的矩形相位光栅和振幅光栅的衍射效率。实验研究了一种利用双相检测法辨向的、以单周期矩形相位光栅作光束结合器的激光光栅测振仪系统。介绍了仪器的工作原理和信号处理方法,给出部分实验结果,实验结果与理论分析相吻合。     

Variable delay line for phased-array antenna based on a chirpedfiber grating

We present a theoretical and experimental analysis of the performance of phased-array antennas steered by a single chirped fiber grating. Two approaches consisting of conventional and single-sideband (SSB) modulation techniques of the optical signal are presented in order to compare their performance and suitability for beamforming applications in microwave antennas. By using a 40-cm-long chirped grating, we measure the phase and amplitude response and calculate the corresponding radiation patterns to demonstrate wide-band operation and continuous spatial scanning properties of both configurations. SSB modulation Is presented as a real alternative to the first one offering broader operation band (4-18 GHz) for a given chirped grating and being less demanding on the fiber grating characteristics     

动态干涉仪的位相光栅衍射效率研究

为了解决普通二维光栅在动态干涉术中光能量利用不足的问题,使用标量衍射理论和傅里叶分析法对矩形正交位相光栅和棋盘型位相光栅的衍射效率进行推导,分别对两种光栅的最佳工作级次选择策略进行研究。分析结果表明,当分光器件为矩形正交位相光栅时,应选择(0, 1)级与(1,0)级作为动态干涉仪的工作级次,光能量利用率达到54.4%;当分光器件为棋盘位相光栅时,应选择(1,1)级作为动态干涉仪的工作级次,光能量利用率达到65%。实验对比了两种光栅在动态干涉仪上的应用效果,当选用(1,1)级作为工作级次时,结果表明使用棋盘型位相光栅的应用效果优于矩形正交位相光栅。因此在动态干涉仪中使用棋盘位相光栅并选用(1,1)级作为工作级次能够消除光能量利用不足对测量造成的影响。     

Circular grating coupled DBR laser with integrated focusing outcoupler

We report on the fabrication and operation of a circular grating coupled, AlGaAs-InGaAs surface-emitting distributed Bragg reflector (DBR) SQW laser with an integrated focusing outcoupler. Electron beam lithography and reactive ion beam etching were used to fabricate the laser with a first-order resonant grating for optical feedback and a separate detuned, chirped second-order grating for outcoupling and focusing the beam.     

Nonlinear analysis of a dielectric distributed feedback laser withcomplex coupling coefficient

An approximate analysis of the nonlinear operation of DFB a dielectric laser with complex coupling coefficient is presented, An expression relating the small signal gain to the output power and the system parameters, including the spatial hole burning effect, is obtained. It is shown that the gain grating, the loss grating, and the higher order Bragg grating all contribute to laser operation above the threshold in a different manner. Moreover, it is possible to achieve a “negative” gain effect in the partly gain-coupled structure operating above the threshold, which depends on the output power level, the distributed loss level and the spatial hole burning effect     

Complex-Coupled DFB Laser Using a Buried SiO2 Grating

In this letter, we report a distributed feedback (DFB) laser having a dielectric grating formed by SiO and InP to explore both the large refractive index difference and the partial gain coupling. Epitaxy lateral overgrowth by metal-organic chemical vapor deposition is conducted to grow the top p-type InP waveguide layer in the dielectric grating template. An index coupling coefficient of about 250 cm is estimated on the laser vertical waveguide structure. The insulating nature of the dielectric grating also partially blocks the injection current flow and modulates the optical gain of the active quantum-well region underneath it. A prototype DFB laser was fabricated and showed a stable single-mode operation with a sidemode suppression ratio larger than 47 dB measured at room temperature and continuous-wave operation. The technology developed can also be used for other applications that require high efficiency grating structures.     

Tunable dual-mode operation in a chirped gratingdistributed-feedback laser

We report on the tunable dual-mode operation of a chirped grating distributed-feedback (DFB) laser device with two integrated modulators which act as tuning sections. A transfer-matrix model is used to simulate the amplified spontaneous emission spectrum for a chirped grating DFB laser. Several types of dual-mode operation are observed for wavelength spacings of 0.5 nm and 1.4 nm corresponding to frequency detunings of 63 GHz and 175 GHz     

分布式光纤光栅传感网络的复用解调技术

波长编码信号解调是实现光纤光栅多参量、多点分布式传感网络的核心技术之一。本文总结了光纤光栅传感信号解调的一般原理和技术难点,分类评述了常用解调方法的工作机理、特点和性能。同时,提出了一种新型的、用宽带光源和可调谐光滤波器(TOF)构成的可调谐窄带光源,对测量光栅阵列和参考光栅进行波长扫描,借助光电探测器和信号处理系统实现复用传感系统的解调技术。     

Properties of a Second Harmonic Gyrotron Cavity with Internal Blazed Grating

Spectral domain analysis, scattering matrix analysis and PIC simulations are used here to design a second harmonic gyrotron cavity with an internal blazed grating which favors operation at the second harmonic of the electron cyclotron frequency rather than operation at the electron cyclotron frequency itself. Based on these simulations, the cavity design is optimized. The results show that a new gyrotron with higher power and higher frequency can be achieved by incorporating such a blazed grating.     

Single mode multiple-element laser array with grating filter

A 1.5-μm wavelength grating filter laser array (GFA) structure which consists of a positive-index-guided multiple-element array region and a laterally unguided grating filter region is proposed and theoretically analyzed for realizing in-phase supermode and simultaneous single-longitudinal-mode operation. A five-element GaInAsP/InP GFA with a lasing wavelength of ~1.5 μm was fabricated and its single-longitudinal-mode/in-phase supermode operation was demonstrated up to four times the threshold current     

复增益耦合型取样光栅DFB激光器的设计制作与性能

A complex-coupled DFB Laser with sampled grating has been designed and fabricated. The key concepts of the approach are to utilize the +1st order reflection of the sampled grating for laser single mode operation, and use a conventional holographic exposure combined with the usual photolithography to fabricate the sampled grating. The typical threshold current of the sampled grating based DFB laser is 25mA, and the optical output is about 10mW at the injected current of 100mA. The lasing wavelength of the device is 1.5385μm, which is the +1st order wavelength of the sampled grating.     

平焦场光栅的成像特性

给出了变栅距四面光栅的光程函数和综合像差的普遍表达式，在此基础上针对我们采用的ＨＩＴＡＣＨＩ变栅距平焦场四面光栅的实际参数，详细研究了它的成像性质，同时还给出了使用该光栅的平焦场光栅谱仪工作在像散和消像散两种模式下的典型实验结果。     

Design and performance of a complex-coupled DFB laser with sampled grating

A complex-coupled DFB laser with sampled grating has been designed and fabricated. The method uses the + 1 st order reflection of the sampled grating for laser single-mode operation. The typical threshold current of the sampled grating based DFB laser is 25 mA, and the optical output is about 10 mW at the injected current of 100 mA. The lasing wavelength of the device is 1.5385μm, which is the +1 st order wavelength of the sampled grating.     

An Analytical Study of the Echelette Grating with Application to Open Resonators

Reflection coefficients of various order diffracted waves are calculated for an echelette grating which finds important use as a component of suboptical resonators. The classical optics approach has been found to be inadequate for deriving reliable results for this configuration. Accurate solution of the boundary value problem associated with the echelette grating is derived by a new method. The results are useful for the design of suboptical resonators which use the echelette grating as a coupling mirror to achieve a single wavelength operation.     

光栅与标准具对称放置的新型脉冲染料激光器

本文进一步完善了光栅在近掠入射条件下应用于脉冲染料激光器的工作。解决了装置中进一步压缩线宽的问题和在近掠入射条件下最佳光栅及其级次的选取问题。提出了一个光栅与标准具对称放置的方案,其结构简单,调节方便,具有较高的能量转换效率和实用价值。单模输出时线宽达几百个兆赫(0.006以下)。     

Single-mode operation of a surface grating distributed feedbackGaAs-AlGaAs laser with variable-width waveguide

Single-mode distributed feedback laser operation can be achieved by introducing an appropriate phase jump within the feedback grating, causing lasing to occur within the stop-band. One possible approach involves variation of the waveguide stripe width in an index-guided structure, in conjunction with a grating of uniform periodicity. If the phase change is allowed to accumulate over a sufficient length of the width perturbed stripe waveguide, a λ/4 shift can be realized. We report the first laser of this type using a surface grating structure with only postgrowth processing     

光纤光栅解调系统信号处理算法的实现

针对目前市场上的光纤光栅解调仪体积大、功耗高的缺点,提出了将DSP应用于光纤光栅解调系统实现波长解调的方案;同时,为了减小DSP运算的数据量,提高光纤光栅解调系统的实时性,提出了一种光谱寻峰算法,通过与Matlab中的峰值检测模块的处理结果进行对比分析,证明了算法的有效性.     

光栅掠入射脉冲染料激光器工作特性的研究

本文研究了无反馈腔结构的高损耗脉冲染料激光器和一般光栅掠入射结构的脉冲染料激光器的输出特性,分别获得了时间平均频带宽度为1.2GHz和2.5GHz的输出,本文还讨论了激光频带与腔参数的依赖关系,给定了光栅掠入射染料激光器的最佳工作条件。     

光纤光栅传感器交叉敏感问题的研究

交叉敏感是光纤光栅固有的问题,已成为制约光纤光栅传感器在实用化等方面的关键问题,为此从光纤Bragg光栅应变、温度交叉敏感的物理机制出发,详细介绍了国内外多种关于交叉敏感问题的解决方案和各类方案的工作原理.     

训练模拟器的评分功能设计

为了使训练更有针对性和计划性,训练模拟器的评估功能应做到评估内容覆盖全面、贴合训练大纲、综合考虑训练过程中的各种因素、评估方式多样灵活等。根据训练模拟器评估功能需求以及已有研制经验,分别讨论了理论考试、操作训练评分、复杂训练课题评分以及辅助评估四种评分方式的设计思路,并提出了一种训练评分的处理流程。数据采集、专家系统和综合模糊评价法技术的应用在训练模拟器评估系统设计中起到很关键的作用。除了对以上关键技术应用的研究,在该课题上的研究应该重点放在提高智能化和灵活性上,以适应未来的复杂大型模拟器或者多模拟器的联网训练。