共查询到10条相似文献,搜索用时 15 毫秒
1.
<正>A sensitive polymer diaphragm based fiber Fabry-Perot(F-P) sensor for aeroacoustic wave measurement is presented.A novel polymer material poly(phthalazinone ether sulfone ketone)(PPESK) diaphragm is used as the acoustic sensing element.The effective dimensions of the diaphragm are 4 mm in diameter and 6μm in thickness.Owing to the good mechanical and optical features of the diaphragm and application of the interferometric/intensity demodulation,a system sensitivity of 31 mV/Pa is achieved in the frequency range of 0.1-12.7 kHz,and a signal-to-noise ratio(SNR) of 29 dB at 1 kHz is obtained.The linear response of the sensor is from 0.35 to 2.82 Pa,corresponding to 85 - 103 dB sound pressure level(SPL)(re:20μPa).The sensor has the potential to be used as a universal and low-cost optical microphone. 相似文献
2.
Application of longitudinal generalized magneto-optical ellipsometry in magnetic ultrathin films
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The longitudinal generalized magneto-optical ellipsometry(GME) method is extended to the measurement of threelayer ultrathin magnetic films. In this work, the theory of the reflection matrix is introduced into the GME measurement to obtain the reflective matrix parameters of ultrathin multilayer magnetic films with different thicknesses. After that, a spectroscopic ellipsometry is used to determine the optical parameter and the thickness of every layer of these samples, then the magneto-optical coupling constant of the multilayer magnetic ultrathin film can be obtained. After measurements of a series of ultrathin Fe films, the results show that the magneto-optical coupling constant Q is independent of the thickness of the magnetic film. The magneto-optical Kerr rotations and ellipticity are measured to confirm the validity of this experiment. Combined with the optical constants and the Q constant, the Kerr rotations and ellipticity are calculated in theory. The results show that the theoretical curve fits very well with the experimental data. 相似文献
3.
Investigation of the limit of lateral beam shifts on a symmetrical metal-cladding waveguide
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This paper reports that Goos--H\"anchen (GH) shifts
occurring on a symmetrical metal-cladding waveguide are
experimentally identified. It was found that there exists a critical
thickness of the upper metal layer, h_cr, above which negative
shift is observed and, reversely, positive shift occurs. Both
positive and negative GH shifts near the critical thickness do not vary
dramatically and can achieve a maximum on the submillimeter scale, which
is different from simulated results using the stationary-phase
method. It also shows that this critical thickness, h_cr, can be
obtained at the position for zero reflectivity by setting the
intrinsic damping to be the same as the radiative damping. The GH
effects observed near the critical thickness are produced by extreme
distortion of the reflected beam profiles, which limits the
amplitude of the GH shift and, further, the sensitivity of the GH optical
sensor based on the symmetrical metal-cladding waveguide. 相似文献
4.
Effect of ultrathin GeO_x interfacial layer formed by thermal oxidation on Al_2O_3 capped Ge
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We propose a modified thermal oxidation method in which an Al2O3 capping layer is used as an oxygen blocking layer (OBL) to form an ultrathin GeOx interracial layer, and obtain a superior Al2O3/GeOx/Ge gate stack. The GeOx interfacial layer is formed in oxidation reaction by oxygen passing through the Al2O3 OBL, in which theAl2O3 layer could restrain the oxygen diffusion and suppress the GeO desorption during thermal treatment. The thickness of the GeOx interfacial layer would dramatically decrease as the thickness of Al2O3 OBL increases, which is beneficial to achieving an ultrathin GeOx interfacial layer to satisfy the demand for small equivalent oxide thickness (EOT). In addition, the thickness of the GeOx interfacial layer has little influence on the passivation effect of the Al2O3/Ge interface. Ge (100) p-channel metal- oxide-semiconductor field-effect transistors (pMOSFETs) using the Al2O3/GeOx/Ge gate stacks exhibit excellent electrical characteristics; that is, a drain current on-off (Ionloft) ratio of above 1 104, a subthreshold slope of - 120 mV/dec, and a peak hole mobility of 265 cm2/V.s are achieved. 相似文献
5.
A new analytical model of high voltage silicon on insulator (SOI) thin film devices 总被引:2,自引:0,他引:2
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A new analytical model of high voltage silicon on insulator (SOI)
thin film devices is proposed, and a formula of silicon critical
electric field is derived as a function of silicon film thickness by
solving a 2D Poisson equation from an effective ionization rate,
with a threshold energy taken into account for electron multiplying.
Unlike a conventional silicon critical electric field that is
constant and independent of silicon film thickness, the proposed
silicon critical electric field increases sharply with silicon film
thickness decreasing especially in the case of thin films, and can
come to 141V/μm at a film thickness of 0.1μm which is
much larger than the normal value of about 30V/μm. From the
proposed formula of silicon critical electric field, the expressions
of dielectric layer electric field and vertical breakdown voltage
(VB,V) are obtained. Based on the model, an ultra thin film
can be used to enhance dielectric layer electric field and so
increase vertical breakdown voltage for SOI devices because of its
high silicon critical electric field, and with a dielectric layer
thickness of 2μm the vertical breakdown voltages reach 852
and 300V for the silicon film thicknesses of 0.1 and 5μm,
respectively. In addition, a relation between dielectric layer
thickness and silicon film thickness is obtained, indicating a
minimum vertical breakdown voltage that should be avoided when an
SOI device is designed. 2D simulated results and some experimental
results are in good agreement with analytical results. 相似文献
6.
Woo-Hu Tsai Kuen-Cherng Lin Shu-Ming Yang Yu-Chia Tsao Ping-Jing Ho 《中国光学快报(英文版)》2014,12(4):42801-69
We describe a surface plasmon resonance-based fiber sensor based on a side-polished graded-index mul- timode fiber, in which an Al-doped zinc oxide/gold (AZO/Au) bilayer is deposited on the side-polished surface of the fiber core to improve the detection sensitivity of the device. The AZO/Au layer is used as the active sensing member of the device with a combination of a 75-nm-thick AZO layer and a 40-nm-thick Au layer. Such a device is then applied to the concentration measurement of CHaCOONa solutions, as an example showing a good response to concentration variation. The results indicate that the additional AZO layer in the active sensing member may lead to higher detection sensitivity and greater measurement stability in the measurements of solution concentration. 相似文献
7.
Interfacial magnetic anisotropy in a Pt/CO1-xFex/Pt multilayer is tuned by doping iron atoms into the cobalt layer. The perpendicular magnetic anisotropy and out-of-plane coercivity are found to decrease with increasing x. For a specific x, the out-of-plane coercivity acquires a maximal value as a function of the thickness of the CoFe layer. At low temperature, the coercivity is enhanced. Small coercivity but reasonably large perpendicular magnetic anisotropy can be obtained by controlling the x and CoFe layer thickness. 相似文献
8.
The photoacoustic model of multilayer with a strong-absorbing surface layer is developed. The phase of ph0toacoustie signal is measured as a function of modulated frequency using apparatus totally controlled by a computer system. The thermal diffusivity, effusivity as well as thickness of several buried layers are obtained independently through the best fit of experimental data according to the theoretical model. The multilayers of thin metal and alloy film are investigated. This method is proved to be valuable particularly in nondestructive examination of subsurface physical properties. 相似文献
9.
Guided-mode resonant Brewster filter consisting of two homogenous layers and a single grating with an equal refractive index
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In this paper,a new type of resonant Brewster filter(RBF) consisting of two homogenous layers and a single grating with an equal refractive index is presented.The properties are studied by using the plane waveguide method(PWM) and rigorous coupled-wave analysis(RCWA).It is found that the variation of the grating thickness does not effectively change the position of the resonant wavelength,however it has a remarkable effect on the line width,and the resonant peak can be adjusted back to its original position by slightly tuning the grating period.Moreover,by simultaneously tuning the thicknesses of the homogeneous layers above and beneath the grating structure,multiple channels can also be obtained when the RBF is illuminated at the Brewster angle calculated with the effective medium theory(EMT) of subwavelength grating.The adjacent optical thickness for acquiring the multiple channels is about three-quarters of the resonant wavelength.Furthermore,it is demonstrated that the line width at the operating resonant wavelength can be appreciably narrowed by tuning the thickness of the homogenous layer to its corresponding thickness without fine tuning the grating period or the thickness.Therefore,it is very useful for designing filters with different line widths at the desired wavelength.In addition,it is shown from our calculations that the symmetrical line feather can be obtained if the total optical thickness for the homogeneous layer meets the special condition. 相似文献
10.
Hexagonal WO3 nanorods are fabricated by a facile hydrothermal process at 180 ℃ using sodium tungstate and sodium chloride as starting materials. The morphology, structure, and composition of the prepared nanorods are studied by scanning electron microscopy, X-ray diffraction spectroscopy, and energy dispersive spectroscopy. It is found that the agglomeration of the nanorods is strongly dependent on the PH value of the reaction solution. Uniform and isolated WO3 nanorods with diameters ranging from 100 nm-150 nm and lengths up to several micrometers are obtained at PH = 2.5 and the nanorods are identified as being hexagonal in phase structure. The sensing characteristics of the WO3 nanorod sensor are obtained by measuring the dynamic response to NO2 with concentrations in the range 0.5 ppm-5 ppm and at working temperatures in the range 25 ℃-250 ℃. The obtained WO3 nanorods sensors are found to exhibit opposite sensing behaviors, depending on the working temperature. When being exposed to oxidizing NO2 gas, the WO3 nanorod sensor behaves as an n-type semiconductor as expected when the working temperature is higher than 50 ℃, whereas, it behaves as a p-type semiconductor below 50 ℃. The origin of the n- to p-type transition is correlated with the formation of an inversion layer at the surface of the WO3 nanorod at room temperature. This finding is useful for making new room temperature NO2 sensors based on hexagonal WO3 nanorods. 相似文献