排序方式: 共有49条查询结果,搜索用时 15 毫秒
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谐振式光纤陀螺系统中,背向散射噪声成为制约其系统精度的重要因素之一.对陀螺双路系统其中一路光波信号进行研究,利用相位调制频谱展开及光场叠加的方法,对光纤环形谐振腔输出光场进行理论分析.理论上载波分量的出现会在系统中引入背向散射噪声,因此仿真分析引入载波分量的幅度,得到采用三角波调制比正弦波更有利于抑制载波分量.以抑制载波分量为目标,搭建自外差载波抑制测试平台,对相位调制器施加三角波与正弦波两种波形调制,得到采用三角波调制时载波抑制比最高可达64.3dB,比正弦波调制时高出6dB,与理论分析相符;在陀螺系统应用中,采用三角波调制时陀螺输出信号载波抑制程度更大,波动更小,更加稳定. 相似文献
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模拟仿真了谐振式光纤环腔的透射谱线以及鉴频曲线,得透射谱线最低谷值对应为调制谐振点,鉴频曲线的线性区为陀螺的工作范围区,线性区中点对应谐振点,可作为标度因数最大值.为了实现谐振点的高精度锁频和稳频,设计了谐振式光纤陀螺角速率测定方案,使用比例积分反馈电路实施锁频,利用正弦波扫描窄线宽激光器(线宽小于1kHz)的压电转化模块,使激光器谐振腔长发生变化,从而改变其输出频率,对谐振光纤环腔随外界环境变化同时进行跟踪和锁定.利用线宽法测试并计算出光纤环形谐振腔的品质因数值为107,对比分析了光纤环腔在谐振点和非谐振点锁定情况下的光电探测实时输出,并通过转动测试,得到两种情况下锁定后陀螺的连续转动效果.计算了光纤陀螺系统理论检测灵敏度,结果表明:谐振点锁定后转动效果对应的陀螺输出电平值为锁定非谐振点转速电平值的3倍,验证了谐振式光学陀螺谐振点锁频的重要性. 相似文献
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Temperature dependence of biaxial strain and its influence on phonon and band gap of GaN thin film 下载免费PDF全文
Hexagonal GaN epilayer grown on sapphire substrate by metal organic
chemical vapour deposition (MOCVD) is studied using Raman scattering
and photoluminescence in a temperature range from 100\,K to 873\,K.
The model of strain (stress) induced by the different lattice
parameters and thermal coefficients of epilayer and substrate as a
function of temperature is set up. The frequency and the linewidth of
$E_2^{\rm high}$ mode in a GaN layer are modelled by a theory with
considering the thermal expansion of the lattice, a symmetric decay
of the optical phonons, and the strain (stress) in the layer. The
temperature-dependent energy shift of free exciton A is determined by
using Varshni empirical relation, and the effect of strain (stress)
is also investigated. We find that the strain in the film leads to a
decreasing shift of the phonon frequency and an about
10meV-increasing shift of the energy in a temperature range from
100\,K to 823\,K. 相似文献
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Wide dynamic range is an important index of the resonator fiber optic gyro(RFOG). The dynamic range is related to the parameters of the fiber ring resonator(FRR). After adopting the appropriate parameters, the resonant curve of a FRR and the synchronous demodulated curve are measured. Based on the closed-loop frequency locking technique, the wide dynamic range is obtained, while the linearity is guaranteed. The experiment's results show that the dynamic range is 480 deg ∕s with less than 1% nonlinearity, and that the bias stability is0.04 deg/s over 2000 s. This Letter demonstrates the scheme for a RFOG with a wide dynamic range. 相似文献
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Pressure effects in AlAs/Inx Ga1-xAs/GaAs resonant tunnelling diodes for application in micromachined sensors 下载免费PDF全文
This paper reports the current-voltage characteristics of [001]-oriented AlAs/InxGa1-xAs/GaAs resonant tunnelling diodes (RTDs) as a function of uniaxial external stress applied parallel to the [110] and the [1^-10] orientations, and the output characteristics of the GaAs pressure sensor based on the pressure effect on the RTDs. Under [110] stress, the resonance peak voltages of the RTDs shift to more positive voltages. For [1^-10] stress, the peaks shift toward more negative voltages. The resonance peak voltage is linearly dependent on the [110] and [1^-0] stresses and the linear sensitivities are up to 0.69 mV/MPa, -0.69 mV/MPa respectively. For the pressure sensor, the linear sensitivity is up to 0.37 mV/kPa. 相似文献
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电容式微机械超声换能器具有宽频带和易于制造二维阵列等优势,已经成为一种重要的新型超声换能器。该文针对图像声呐系统对新型超声换能器的迫切需求,提出了一种电容式微机械超声换能器结构和参数,并利用硅微加工技术制备出了该换能器,最后对其主要性能参数进行了测试和分析。测试结果表明该换能器具有发射和接收超声波的功能,中心工作频率为1.965 MHz,6 dB相对带宽达到109.4%,在1 MHz、2 MHz和3 MHz频率时的接收灵敏度分别为-218.29 d B、-219.39 dB和-218.11 dB。该文研制的电容式微机械超声换能器显示出了优秀的宽频带特性,且工作频率和接收灵敏度性能均基本满足了高频图像声呐系统的需求。 相似文献
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Coupled-resonator-induced transparency in two microspheres as the element of angular velocity sensing 下载免费PDF全文
We proposed a two-coupled microsphere resonator structure as the element of angular velocity sensing under the Sagnac effect.We analyzed the theoretical model of the two coupled microspheres,and derived the coupled-resonatorinduced transparency(CRIT) transfer function,the effective phase shift,and the group delay.Experiments were also carried out to demonstrate the CRIT phenomenon in the two-coupled microsphere resonator structure.We calculated that the group index of the two-coupled sphere reaches n_g = 180.46,while the input light at a wavelength of 1550 nm. 相似文献