• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    A novel plasmonic refractive index sensor based on gold/silicon complementary grating structure?

    2021-03-11 08:32:38XiangxianWang王向賢JiankaiZhu朱劍凱YueqiXu徐月奇YunpingQi祁云平LipingZhang張麗萍HuaYang楊華andZaoYi易早
    Chinese Physics B 2021年2期
    關(guān)鍵詞:張麗萍楊華

    Xiangxian Wang(王向賢), Jiankai Zhu(朱劍凱), Yueqi Xu(徐月奇), Yunping Qi(祁云平),Liping Zhang(張麗萍), Hua Yang(楊華), and Zao Yi(易早)

    1School of Science,Lanzhou University of Technology,Lanzhou 730050,China

    2College of Physics and Electronic Engineering,Northwest Normal University,Lanzhou 730070,China

    3Joint Laboratory for Extreme Conditions Matter Properties,Southwest University of Science and Technology,Mianyang 621010,China

    Keywords: plasmonic sensor,gold,silicon,grating

    1. Introduction

    In the past few decades, the development of various nanofabrication technologies has provoked the enormous growth of nanostructures in various applications such as photocatalysis,[1–3]absorption enhancements,[4,5]photonic crystals,[6,7]and other fields.[8]Simultaneously, the fabrication of metal micro-nano structures mainly benefits from the rapid growth of electron beam lithography(EBL)and focused ion beam(FIB)milling.The realization of cost-effective metal nanostructures greatly improves the possibilities of their integration in the optical field. When the characteristic size of the metal nanostructure is of sub-wavelength order, a kind of electromagnetic motion mode of light and electron closely combined under the action of external electromagnetic wave,namely surface plasmons,cannot be ignored.[9]In reality,the structures and devices based on surface plasmons make it possible to manipulate and control photons on the nanoscale,which provides a new solution for realizing smaller,faster,and more efficient nanophotonic devices. Moreover, many applications of metal micro-nano structures,such as absorbers,[10]fiber sensors,[11,12]surface-enhanced Raman,[13–15]are all related to the surface plasmons generated by the close interaction between metal nanostructures and incident light.

    At present, surface plasmons have a considerable application prospect in the fields of optical sensing, due to their high sensitivity to the physical and chemical properties of the environment, as well as their action range can be controlled at the nano level. In addition, surface plasmons based biochemical sensors are also attracting attention because of their advantages of fast detection speed, high specificity, samplefree labeling,[16,17]and online real-time analysis.[17]However,the plasmonic refractive index (RI) sensors based on prism coupling, which has been successfully commercialized, have gradually exhibited drawbacks in miniaturization and integration owing to its bulky volume. In recent years,the integrated grating coupled plasmonic RI sensors have attracted much attention since it is compatible with the portable development concept of future sensors.[18]Moreover, the noise reduction and light collection are other significant improvement advantages because the grating coupling based plasmonic RI sensors can be excited via normal incidence. Therefore, it is of great significance to design grating coupled plasmonic RI sensor with higher sensitivity,a higher figure of merit(FOM),and a more straightforward manufacturing process(easy to manufacture in a large area)to meet the future needs of RI sensing.

    In this work,we propose a novel complementary grating structure for plasmonic RI sensing. Compared with the traditional grating coupled plasmonic RI sensors, our structure can more effectively couple the surface plasmons excited via grating to the environment of the analyte and significantly reduce the full width at half maximum(FWHM),thus improved the FOM. A broadband simulation was performed to extract the structure spectrum characteristics based on TM polarization, and the electric field distributions were obtained using the finite-difference time-domain (FDTD) method. We find that multiple surface plasmon resonance modes can exist in the complementary grating structure. Furthermore,the resonance mode excited via the first-order diffraction coupling of the grating is quite suitable for RI sensing because of its extremely narrow FWHM.The influences of grating geometric variables on resonance behavior are discussed in detail to obtain the appropriate geometric ranges for RI sensing.Finally,the RI sensing performances of the structure are reflected plainly by two important physical parameters,sensitivity and FOM.

    2. Structural design

    The three-dimensional schematic diagram and the twodimensional profile diagram of the structure are respectively shown in Figs. 1(a) and 1(b). The sensing structure is composed of Si grating,Au grating,and glass substrate. The structure is mainly composed of complementary and directly contacted Si and Au gratings. In essence, it is a functional layer based on the Schottky junction,which is advantageous to current silicon electronic devices from the integration point of view. The analyte is located on the upper surface of the entire structure during the actual RI sensing. Here, the RI of the analyte and the period of the Au/Si grating are assumed to be 1 and 1700 nm, respectively, unless otherwise stated. For the convenience of discussion,grating geometric variables are shown in Fig.1(b),which are the Au grating channel width w,Au grating channel depth td,and the thickness of Si film tsin the Si grating.

    Fig.1. The three-dimensional schematic diagram (a) and the twodimensional profile diagram(b)of the complementary grating structure.From top to bottom are Si grating,Au grating,and glass substrate. The black and blue arrows represent the propagation direction and polarization direction of the incident light,respectively.

    As shown by the arrows in Fig.1,this plasmonic structure is excited via vertical incident light with a polarization direction along the periodic direction(TM mode). In the structural design,the purpose of the Au grating is to compensate for the appropriate momentum to excite the surface plasmons propagating along the functional layer composed of complementary gratings. The thickness of the designed Au grating is thick enough; thus,the light transmission of the structure is almost zero in a wide frequency band. The Si grating, complementary to Au grating,has two main objectives. On the one hand,the Si grating makes the contact surface between the analyte and the structure smooth(easy to clean analytes). On the other hand, Si grating can assist Au grating to couple more energy of surface plasmons to the environment of analyte(discussed below). In the numerical simulation, the optical constants of Si and glass substrate (SiO2) are derived from previous experimental values,[19,20]and the dielectric constant of gold is selected from the experimental data supported by the Drude model.[21]

    3. Results and discussion

    3.1. Plasmonic responses of the structure

    The black curve in Fig.2 shows the reflection spectrum of the complementary grating structure in a wide wavelength range of 1400 nm to 4000 nm. Here, the geometric parameters of the complementary grating structure are w=400 nm,td=160 nm, and ts=30 nm, respectively. To illustrate the advantages of the complementary grating structure, we also simulate the reflection spectrum of the structure with only Au grating under the same geometric parameters,as shown in the red curve in Fig.2. It can be clearly seen from the comparison that the complementary grating structure with a layer of Si can excite more surface plasmon resonance modes and can effectively reduce the FWHM of the resonance peak. According to the spectral response of the complementary grating structure,the resonance mode excited at 1708 nm has great advantages in RI sensing due to its strong resonance intensity(reflectivity almost 0)and extremely narrow FWHM(about 5.4 nm). It is worth mentioning that the resonance mode at 3189 nm may have application potential in broadband absorption,benefit by its FWHM of nearly 500 nm.

    Fig.2. Reflection spectra of the structures. The black curve shows the reflection spectrum of the complementary grating structure at the geometric variables of w=400 nm,td =160 nm, and ts =30 nm, respectively. The red curve shows the reflection spectrum of the structure with only Au grating under the same geometric parameters.

    To intuitively reveal the resonance mechanism caused by grating coupling,we calculated the electric field distributions of the grating coupling structures for each resonance mode(corresponding to Fig.2)in Fig.3. Figure 3(a)shows the electric field distribution at 1813 nm,which is the only plasmonic resonance mode excited via the structure with only Au grating. Figures 3(b)–3(d) show the electric field distributions of the complementary grating structure at resonance wavelengths of 1558 nm, 1708 nm, and 3189 nm, respectively. As can be seen, in the case of Fig.3(a), the electric fields are found to leak into the environment of the analytes, which is the signature of propagating surface plasmon. It can be confirmed that this mode is caused by the first-order diffraction coupling of the Au grating. For Fig.3(c), one can observe a similar phenomenon in the complementary grating structure and draw the same conclusion. Thus, the 1708 nm mode can be illustratively called propagation-mode in the complementary grating structure. However,it can also be observed that the existence of Si grating in complementary grating structure makes the energy of surface plasmons excited by Au grating more evenly coupled to the environment of analytes. Furthermore, the Si grating that flattens the propagation interface of the surface plasmon is the main reason for reducing the FWHM of the first-order diffraction coupled resonance of Au gratings. Remarkably, both these two characteristics caused by complementary gratings are conducive to RI sensing. Subsequently,it can be observed from Fig.3(b) that the weak resonance of Au/Si interface in the channel of Au grating is the reason for the reflection valley at 1558 nm,and a standing wave is formed in the environment of analyte due to the reflection of the incident light. As shown in Fig.3(d),the large capture of the field energy via the Au grating channel is responsible for the resonance mode at 3189 nm,which can be called channel-mode.

    To further reveal the role of grating on the excitation of surface plasmon resonances,we theoretically verify the simulation results via the 1D grating equation. Incident light scattering on metal nanostructures results in a wide range of directions for the propagation vector. Then, surface plasmon resonance is generated when the following momentum matching conditions are satisfied:[22]

    where k0nsin? is the k-vector of the incident light in the xdirection, and 2πm/P is the additional momentum compensated via 1D grating.More specifically,k0=2π/λ is the propagation constant in free space, nais the RI of the analyte, εmis the complex dielectric constant of the gold, ? is the incident angle, P is the 1D grating period, m are the diffraction orders of 1D gratings and are integers. In the case of normal incidence,the above equation can be reduced to

    where λresrepresents the resonance wavelength.When m=1,the 1708 mode is in good agreement with Eq.(2)obtained via theoretical analysis, which fully testifies that the 1708 mode is excited by the first-order subwavelength diffraction of the grating. The theoretical result is also consistent with the qualitative analysis of the electric field distribution in Fig.3(c).

    Fig.3. The electric field distributions of the structures corresponding to each resonance wavelength in Fig.2 and the white dashed line outlined the structures.The electric field distribution of the structure with only Au grating at the resonance wavelength of(a)1813 nm. The electric field distributions of a complementary grating structure at the resonance wavelengths of(b)1558 nm,(c)1708 nm,and(d)3189 nm,respectively.

    3.2. Structural optimization

    Considering the purpose of using this structure for RI sensing, the following discussion focuses on the 1708 nm mode (propagation-mode), which has strong resonance (low reflectivity)and narrow FWHM,and has extensive interaction with the environment of the analyte. Firstly, the geometric parameters of the structure are optimized, and the geometric parameter tolerance suitable for RI sensing is obtained. Figure 4(a) shows the reflection spectra at the waveband where the propagation-mode is located when w changes from 280 to 680 in a step size of 100 nm with tdand tsfixed at 160 nm and 30 nm, respectively. It can be observed that the resonance wavelengths move towards the shorter wavelength,and the reflectivity decreases first and then increases with the increase of w, while the FWHM presents fluctuation. Hence, a choice of the channel width w of 380 nm(red line)resulted in a decent value of signal contrast. Figure 4(b)shows the reflectivity spectra for w of 380 nm,tsof 30 nm,and variable channel death tdin step size of 20 nm. It can be noticed that the reflectivity decreases to the minimum value and then increases,resulting in an optimal value of 160 nm for td(blue line). Figure 4(c) shows the reflection spectra for w of 380 nm, tdof 160 nm,and with tschanged from 0 nm to 40 nm in step size of 10 nm. It can be observed that with the increase of ts, the resonance wavelength shifts to the long wavelength and is accompanied by the reflectivity gets lower,and the FWHM gradually widened. Here, tsis optimized to be 30 nm (blue line)because there is a trade-off between dip strength and FWHM.

    Fig.4. Influences of(a)channel width w,(b)channel depth td,and(c)Si film thickness ts on the 1708 nm mode(propagation-mode).

    According to the above discussion,the optimum geometric parameters of the complementary grating structure used for RI sensing are w of 380 nm, tdof 160 nm, and tsof 30 nm,respectively. In addition, two important points can be simultaneously derived from the above discussion on the influence of geometric parameters on propagation-mode: (i)in terms of sensing, this structure is capable of exciting the strong resonances with sensing capability in a wide range of grating variables,which reveals a remarkably high tolerance to geometric parameters of the structure in the fields of RI sensing;(ii)the variations of w, td, and tsshow the minor effect on the peak position of the propagation-mode, this is because the change of the geometric parameters does not alter the essence of Au grating diffraction,and further confirms that the propagationmode at 1708 nm is indeed aroused by grating diffraction after compensating optical momentum.

    3.3. The sensing performance of the structure

    Based on the above analysis of the plasmonic responses of the complementary grating structure, the sensing performances of the propagation-mode are discussed in detail. Via introducing two crucial physical parameters, sensitivity (S)and figure of merit (FOM), we follow the common knowledge in the field of RI sensing. The RI sensitivity of a plasmonic sensor is generally reported in nanometers of peak shift per refractive index unit (nm/RIU), i.e., S = ?λ/?n.The sensing precision depends on higher sensitivity and narrower FWHM;thus,the concept of FOM can be derived,i.e.,FOM=S/FWHM.

    Figure 5(a) shows the reflection spectra of the structure under different analyte RI in the waveband where the propagation-mode is located. Here, we assume that the analytes are gases, and their RI varies from 1.0 to 1.1 in step size of 0.02. As shown, the resonance wavelength of the propagation-mode moves to the long-wavelength equidistantly with the even increases of analyte RI.It is also observed that the sensing process is very stable,which is reflected in the fact that the reflectivity and the FWHM of the resonance peaks are almost unchanged.Figure 5(b)shows the relationship between the resonance wavelength and the FOM of the propagationmode with the analyte RI. It is more intuitive to observe that the resonance wavelengths are linearly sensitive to the change of analyte RI.According to the definition of S,the slope of the black line in Fig.5(b)is the value of S and keeps a constant of 1642 nm/RIU.In the range of analyte RI being gas,the FOM is all above 300 RIU?1,and the highest can reach 409 RIU?1.The S of this plasmonic sensor is quite high compared with the RI sensors in recent reports,[23–27]and the FOM is higher than that obtained in other previous studies.[28–31]For Fig.5(a),an interesting phenomenon can also be observed. The mode at about 1558 nm (described in detail in Fig.2) presents insensitive to analyte RI, which indicates the potential application in the RI sensing of self-referenced.[32]The reason can be explained from Fig.3(b), which is the electric field distribution under this mode. One can observe from Fig.3(b)that the region of this weak plasmonic resonance is only confined in the channel of Au grating,and has no effect on the external environment of the analyte.

    Fig.5. (a) Reflective spectra of the complementary grating structure with the optimum geometric parameters when the analyte RI ranges from 1.0 to 1.1 in steps of 0.02. (b)The relationship of resonance wavelengths and FOM with analyte RI in propagation-mode.

    The complementary grating structure we designed can be used not only as a gas RI sensor but also as a liquid RI sensor.Figure 6(a) shows the reflection spectra under the waveband where the propagation-mode is located when the analyte RI varies from 1.3 to 1.4 (within the analyte RI range near liquid). Here,the values of w,td,and tsare the optimized parameters under the grating period equals to 1200 nm. As shown in Fig.6(a), the stable sensing ability of the resonance peak can still be observed, which is shown in the linear sensitivity with the even change of analyte RI and the almost constant FWHM. It is noted that when the structure is used for liquid sensing,the sensing waveband can be the same as that for gas sensing. This is because although the increase of analyte RI will lead to the redshift of the resonance peak,the decrease of the period will lead to the blueshift of that. The flexibility of geometric parameter change is also illustrated when the structure is used for RI sensing. Figure 6(b) shows the sensitivity curve used to calculate S and the relationship between FOM and analyte RI.The sensitivity of the structure used for liquid sensing is estimated to be 1212 nm/RIU,and its FOM is stabilized at about 135 RIU?1. Compared with the structure used in gas sensing, the sensitivity of liquid sensing is obviously reduced. This is due to the decrease of the period,which corresponding to reduce the interaction range between the surface plasmon and the environment of the analyte.

    Fig.6. (a) Reflective spectra of the complementary grating structure when the analyte RI ranges from 1.3 to 1.4 in steps of 0.02.Here,the geometric parameters of the structure are with grating period=1200 nm,w=400 nm, td =180 nm, and ts =30 nm. (b) The relationship of resonance wavelength and FOM with analyte RI in propagation-mode.

    4. Conclusion

    In conclusion, a surface plasmon RI sensor based on a complementary grating structure composed of Au and Si is presented. The effective energy couplings between the surface plasmon and the incident light are fully proved by the detailed discussion of the structure plasmonic responses. A propagation-mode with narrow FWHM and high strength occurs via the first-order diffraction of the complementary grating structure, making it very suitable for RI sensing. After optimizing the geometrical parameters of the structure, the S and the highest FOM of the structure are 1642 nm/RIU and 409 RIU?1,respectively,in the analyte of gas.Moreover,flexible geometric parameters regulation makes the structure can be used for liquid sensing in the same waveband as gas sensing. This plasmonic RI sensor is simple to manufacture and has stable sensing performance in the case of the analytes being gas and liquid. Thus, this sensor can be widely used in biological and chemical RI sensing fields.

    猜你喜歡
    張麗萍楊華
    Effect of spin on the instability of THz plasma waves in field-effect transistors under non-ideal boundary conditions
    Molecular dynamics simulations of mechanical properties of epoxy-amine: Cross-linker type and degree of conversion effects
    石磨
    金山(2022年6期)2022-06-24 20:38:53
    楊華作品
    Generation of mid-infrared supercontinuum by designing circular photonic crystal fiber
    汽車ABS控制仿真分析
    A class of two-dimensional rational maps with self-excited and hidden attractors
    A multi-band and polarization-independent perfect absorber based on Dirac semimetals circles and semi-ellipses array?
    Three dimensional nonlinear shock waves in inhomogeneous plasmas with different size dust grains and external magnetized field
    張麗萍 勿忘初心 立己達(dá)人
    美女大奶头黄色视频| 深夜精品福利| 人妻 亚洲 视频| 一区二区日韩欧美中文字幕| 黄片小视频在线播放| 看免费成人av毛片| 久久久国产精品麻豆| 欧美日韩一区二区视频在线观看视频在线| 亚洲av日韩在线播放| 欧美精品人与动牲交sv欧美| 国产精品一国产av| 午夜老司机福利片| 久久久久久久国产电影| 亚洲欧美中文字幕日韩二区| 卡戴珊不雅视频在线播放| a 毛片基地| 国产精品免费视频内射| 亚洲一区中文字幕在线| 777久久人妻少妇嫩草av网站| 欧美日韩av久久| 老司机靠b影院| 十八禁高潮呻吟视频| 男人添女人高潮全过程视频| 少妇被粗大的猛进出69影院| 亚洲国产精品999| 女人久久www免费人成看片| 欧美激情极品国产一区二区三区| 亚洲成人国产一区在线观看 | 亚洲国产欧美在线一区| 国产精品 欧美亚洲| 国产精品女同一区二区软件| 丝袜美足系列| 欧美精品亚洲一区二区| 老汉色∧v一级毛片| 国产亚洲av片在线观看秒播厂| 亚洲人成网站在线观看播放| 久久鲁丝午夜福利片| 欧美日韩一区二区视频在线观看视频在线| 91aial.com中文字幕在线观看| 高清av免费在线| 亚洲欧美清纯卡通| 丝袜喷水一区| 大话2 男鬼变身卡| 国产男女内射视频| 免费在线观看视频国产中文字幕亚洲 | 欧美另类一区| 久久久久精品性色| 秋霞伦理黄片| 午夜日本视频在线| 中国国产av一级| 日韩一区二区三区影片| 尾随美女入室| 亚洲成色77777| 亚洲一卡2卡3卡4卡5卡精品中文| 亚洲熟女精品中文字幕| 99热国产这里只有精品6| 啦啦啦在线观看免费高清www| 黄片播放在线免费| 夜夜骑夜夜射夜夜干| 久久久精品区二区三区| 十八禁高潮呻吟视频| 免费看不卡的av| 国产高清不卡午夜福利| 亚洲激情五月婷婷啪啪| 久久久久精品久久久久真实原创| 欧美日韩亚洲国产一区二区在线观看 | 熟妇人妻不卡中文字幕| 亚洲av日韩精品久久久久久密 | 成人国语在线视频| 精品少妇久久久久久888优播| 我的亚洲天堂| 日韩中文字幕欧美一区二区 | 欧美亚洲 丝袜 人妻 在线| 国产高清国产精品国产三级| 亚洲精品在线美女| av有码第一页| 日本wwww免费看| 在线观看免费高清a一片| 999久久久国产精品视频| 女性生殖器流出的白浆| 久久久精品国产亚洲av高清涩受| 日日爽夜夜爽网站| 秋霞在线观看毛片| tube8黄色片| 中文字幕人妻丝袜一区二区 | 色播在线永久视频| 激情视频va一区二区三区| 午夜影院在线不卡| 18禁国产床啪视频网站| 国产一区二区激情短视频 | 亚洲av在线观看美女高潮| 91成人精品电影| 男女午夜视频在线观看| 亚洲精品久久成人aⅴ小说| 一级毛片黄色毛片免费观看视频| 国产亚洲欧美精品永久| 亚洲欧美日韩另类电影网站| 黄片小视频在线播放| 一区在线观看完整版| 亚洲色图综合在线观看| 97在线人人人人妻| 国产成人精品久久二区二区91 | tube8黄色片| 亚洲一码二码三码区别大吗| 国产片内射在线| 一区二区三区激情视频| 日韩熟女老妇一区二区性免费视频| 少妇人妻久久综合中文| 在线 av 中文字幕| 成人午夜精彩视频在线观看| 国产黄频视频在线观看| 午夜福利视频精品| 在线观看人妻少妇| 中文天堂在线官网| 9色porny在线观看| 免费黄网站久久成人精品| 国产免费现黄频在线看| 可以免费在线观看a视频的电影网站 | 国产精品.久久久| 日本wwww免费看| 老司机深夜福利视频在线观看 | 精品亚洲成a人片在线观看| 天堂中文最新版在线下载| 欧美日韩亚洲国产一区二区在线观看 | 亚洲自偷自拍图片 自拍| 日韩 欧美 亚洲 中文字幕| 久久久亚洲精品成人影院| 搡老乐熟女国产| 悠悠久久av| 人人妻人人澡人人爽人人夜夜| 亚洲精品乱久久久久久| 一二三四在线观看免费中文在| 人人妻人人爽人人添夜夜欢视频| 亚洲欧美成人综合另类久久久| 一区二区三区乱码不卡18| 欧美在线黄色| av在线观看视频网站免费| 久久97久久精品| av在线app专区| 成人毛片60女人毛片免费| 亚洲精品国产色婷婷电影| 欧美 日韩 精品 国产| 国产免费现黄频在线看| 亚洲精品国产一区二区精华液| 精品少妇一区二区三区视频日本电影 | 超色免费av| 丁香六月欧美| 午夜影院在线不卡| 国产精品偷伦视频观看了| 国产成人a∨麻豆精品| 亚洲国产毛片av蜜桃av| 汤姆久久久久久久影院中文字幕| 黄色毛片三级朝国网站| 免费少妇av软件| 免费高清在线观看视频在线观看| 王馨瑶露胸无遮挡在线观看| 国产成人系列免费观看| 亚洲精品久久久久久婷婷小说| 啦啦啦在线免费观看视频4| 涩涩av久久男人的天堂| 日韩av在线免费看完整版不卡| 日韩成人av中文字幕在线观看| 韩国精品一区二区三区| 亚洲一码二码三码区别大吗| 久久久久久久精品精品| 男女午夜视频在线观看| 国产精品国产三级专区第一集| 久久 成人 亚洲| 国产成人系列免费观看| 如日韩欧美国产精品一区二区三区| 9191精品国产免费久久| 久久久精品免费免费高清| 美女主播在线视频| 在现免费观看毛片| 91精品三级在线观看| 色吧在线观看| 欧美成人午夜精品| 黑丝袜美女国产一区| 成人三级做爰电影| 蜜桃国产av成人99| 亚洲欧美精品自产自拍| 精品一区二区三区av网在线观看 | 久久精品亚洲av国产电影网| 精品久久久精品久久久| 久久av网站| 99久久精品国产亚洲精品| a 毛片基地| 在线天堂中文资源库| 亚洲国产欧美在线一区| 如何舔出高潮| 高清黄色对白视频在线免费看| 久久人人爽av亚洲精品天堂| av在线老鸭窝| 欧美日韩视频精品一区| 美女福利国产在线| 纯流量卡能插随身wifi吗| 精品国产国语对白av| 成年av动漫网址| 国产亚洲精品第一综合不卡| 国产精品二区激情视频| 日韩人妻精品一区2区三区| 一级毛片电影观看| 97人妻天天添夜夜摸| 午夜福利一区二区在线看| 亚洲美女黄色视频免费看| 国产精品三级大全| 精品卡一卡二卡四卡免费| 国产在线一区二区三区精| 精品国产露脸久久av麻豆| 亚洲欧洲精品一区二区精品久久久 | 亚洲国产精品国产精品| 亚洲精品久久久久久婷婷小说| av国产久精品久网站免费入址| 久久狼人影院| 久久久久精品久久久久真实原创| 亚洲精品第二区| videosex国产| 搡老乐熟女国产| 国产亚洲精品第一综合不卡| 一区在线观看完整版| 国产老妇伦熟女老妇高清| 亚洲国产日韩一区二区| √禁漫天堂资源中文www| 久久久久久人人人人人| av网站免费在线观看视频| 一二三四中文在线观看免费高清| 午夜福利一区二区在线看| 精品一区二区免费观看| 亚洲精品在线美女| 伊人亚洲综合成人网| 毛片一级片免费看久久久久| 亚洲成人国产一区在线观看 | 热99国产精品久久久久久7| 精品少妇黑人巨大在线播放| 亚洲综合色网址| 欧美日韩亚洲高清精品| 国产极品天堂在线| 亚洲四区av| 国产欧美亚洲国产| 成人影院久久| 青春草视频在线免费观看| 欧美日韩一级在线毛片| 国产精品免费视频内射| 精品免费久久久久久久清纯 | 亚洲av成人不卡在线观看播放网 | 狠狠婷婷综合久久久久久88av| 亚洲情色 制服丝袜| 欧美97在线视频| 成人国产麻豆网| 日韩一区二区三区影片| 纵有疾风起免费观看全集完整版| 99九九在线精品视频| 久久亚洲国产成人精品v| 亚洲av福利一区| 伊人久久大香线蕉亚洲五| 视频在线观看一区二区三区| 亚洲自偷自拍图片 自拍| 19禁男女啪啪无遮挡网站| 一级毛片电影观看| 国产xxxxx性猛交| 免费在线观看黄色视频的| 国产亚洲av高清不卡| 肉色欧美久久久久久久蜜桃| 91精品国产国语对白视频| 国产精品久久久人人做人人爽| 成人国语在线视频| 亚洲av成人不卡在线观看播放网 | 亚洲国产欧美一区二区综合| 婷婷色综合www| av有码第一页| 天美传媒精品一区二区| 亚洲成人国产一区在线观看 | 午夜激情av网站| 国产精品av久久久久免费| 亚洲av电影在线观看一区二区三区| 黄色 视频免费看| 精品少妇黑人巨大在线播放| 老鸭窝网址在线观看| 亚洲综合色网址| 我要看黄色一级片免费的| 青春草视频在线免费观看| 成人黄色视频免费在线看| a 毛片基地| 香蕉丝袜av| 黄色怎么调成土黄色| 久久久久网色| 在线观看国产h片| 最近2019中文字幕mv第一页| avwww免费| 亚洲激情五月婷婷啪啪| 午夜免费鲁丝| 免费黄网站久久成人精品| 国产有黄有色有爽视频| 男女边吃奶边做爰视频| 亚洲成人一二三区av| videosex国产| 在线观看三级黄色| 麻豆乱淫一区二区| 看十八女毛片水多多多| 在线观看三级黄色| 亚洲精品在线美女| 国产精品一区二区在线观看99| xxx大片免费视频| 一级黄片播放器| 亚洲成色77777| 丰满乱子伦码专区| 亚洲精品在线美女| 久久女婷五月综合色啪小说| 天天操日日干夜夜撸| 国产成人精品久久久久久| 午夜久久久在线观看| 亚洲精品成人av观看孕妇| 亚洲,欧美,日韩| 性少妇av在线| 亚洲综合精品二区| 日本欧美视频一区| 国产精品.久久久| 黄片无遮挡物在线观看| 午夜久久久在线观看| 欧美精品亚洲一区二区| 成年人午夜在线观看视频| 亚洲国产精品成人久久小说| 精品视频人人做人人爽| 国产精品女同一区二区软件| 大片免费播放器 马上看| 亚洲第一av免费看| 久久久精品区二区三区| 男女床上黄色一级片免费看| 久久久久精品久久久久真实原创| 纯流量卡能插随身wifi吗| 国产精品一国产av| 丝袜在线中文字幕| 中文字幕人妻熟女乱码| 午夜精品国产一区二区电影| 99热国产这里只有精品6| 老司机靠b影院| 91国产中文字幕| 侵犯人妻中文字幕一二三四区| 国产精品久久久久久人妻精品电影 | 极品少妇高潮喷水抽搐| 性少妇av在线| 亚洲伊人色综图| 少妇被粗大猛烈的视频| 熟妇人妻不卡中文字幕| 久久久精品国产亚洲av高清涩受| 999久久久国产精品视频| 婷婷色综合大香蕉| 18禁观看日本| 少妇人妻 视频| 亚洲精品国产av蜜桃| 99精品久久久久人妻精品| 婷婷成人精品国产| 婷婷色综合大香蕉| 亚洲美女搞黄在线观看| 免费不卡黄色视频| 在线观看人妻少妇| 最近最新中文字幕免费大全7| 国产深夜福利视频在线观看| 亚洲av男天堂| 亚洲成人免费av在线播放| 国产麻豆69| 久久精品国产a三级三级三级| 精品国产乱码久久久久久小说| 亚洲成人一二三区av| 如日韩欧美国产精品一区二区三区| 在线观看www视频免费| 大香蕉久久成人网| 韩国高清视频一区二区三区| 亚洲天堂av无毛| 国产一级毛片在线| 国产国语露脸激情在线看| 伊人久久大香线蕉亚洲五| 亚洲欧美成人综合另类久久久| 伊人久久大香线蕉亚洲五| 亚洲美女视频黄频| 午夜福利视频在线观看免费| 成年女人毛片免费观看观看9 | 国产在线免费精品| 久久性视频一级片| 久久热在线av| av在线app专区| 天天躁夜夜躁狠狠久久av| 人妻人人澡人人爽人人| 欧美日韩亚洲综合一区二区三区_| 热re99久久国产66热| 99re6热这里在线精品视频| 看免费av毛片| 女性生殖器流出的白浆| 日韩免费高清中文字幕av| 国产av码专区亚洲av| 美国免费a级毛片| 免费女性裸体啪啪无遮挡网站| 热99国产精品久久久久久7| 免费观看人在逋| 无限看片的www在线观看| 亚洲欧美精品自产自拍| 亚洲欧美精品综合一区二区三区| 在线观看免费日韩欧美大片| 中文字幕亚洲精品专区| 国产成人免费观看mmmm| 在线观看一区二区三区激情| 国产精品三级大全| 人人妻人人爽人人添夜夜欢视频| 一二三四中文在线观看免费高清| 国产熟女欧美一区二区| 亚洲国产精品成人久久小说| 亚洲av欧美aⅴ国产| 日韩免费高清中文字幕av| 欧美日本中文国产一区发布| 亚洲成国产人片在线观看| www日本在线高清视频| 男女床上黄色一级片免费看| 男女高潮啪啪啪动态图| 亚洲国产精品国产精品| 一级,二级,三级黄色视频| 国产1区2区3区精品| 国产精品麻豆人妻色哟哟久久| 美女主播在线视频| 精品少妇一区二区三区视频日本电影 | 中文字幕人妻丝袜一区二区 | 在线观看免费视频网站a站| 日韩一卡2卡3卡4卡2021年| 亚洲精品国产区一区二| 国产女主播在线喷水免费视频网站| 最近中文字幕高清免费大全6| 亚洲人成网站在线观看播放| xxx大片免费视频| av线在线观看网站| 亚洲av国产av综合av卡| 超碰成人久久| 精品国产一区二区三区久久久樱花| 看免费av毛片| av视频免费观看在线观看| 亚洲国产中文字幕在线视频| 高清视频免费观看一区二区| 美女福利国产在线| 男女免费视频国产| 欧美成人午夜精品| 视频区图区小说| 亚洲成人免费av在线播放| 国产男人的电影天堂91| 午夜福利乱码中文字幕| 国产精品一区二区在线不卡| 国产精品.久久久| 夜夜骑夜夜射夜夜干| 母亲3免费完整高清在线观看| 在线免费观看不下载黄p国产| 欧美日韩视频精品一区| videos熟女内射| 国产激情久久老熟女| 国产伦理片在线播放av一区| 国产1区2区3区精品| 免费观看人在逋| 国产精品一区二区精品视频观看| 制服诱惑二区| 在线观看人妻少妇| 国产成人免费无遮挡视频| 成人免费观看视频高清| 老司机影院成人| 国产精品国产三级专区第一集| 欧美日韩亚洲高清精品| 狂野欧美激情性xxxx| 亚洲人成网站在线观看播放| 啦啦啦视频在线资源免费观看| 国产av精品麻豆| 9热在线视频观看99| 黄片无遮挡物在线观看| 男女午夜视频在线观看| 丰满乱子伦码专区| 大香蕉久久网| av不卡在线播放| 日韩av不卡免费在线播放| 国产成人欧美| 一本—道久久a久久精品蜜桃钙片| avwww免费| 人人妻人人添人人爽欧美一区卜| 国产精品av久久久久免费| 国产精品99久久99久久久不卡 | 亚洲图色成人| 各种免费的搞黄视频| 亚洲人成网站在线观看播放| 少妇猛男粗大的猛烈进出视频| 黑丝袜美女国产一区| 黄色视频在线播放观看不卡| 最黄视频免费看| 亚洲欧美色中文字幕在线| 制服人妻中文乱码| 久久精品人人爽人人爽视色| 欧美日韩精品网址| 国产熟女午夜一区二区三区| 午夜福利视频在线观看免费| 久久影院123| 女性生殖器流出的白浆| 一边摸一边抽搐一进一出视频| 日本av免费视频播放| 丁香六月天网| 丰满迷人的少妇在线观看| 久久国产精品大桥未久av| 欧美日韩av久久| 美女主播在线视频| 精品国产一区二区三区四区第35| 久久久久久久精品精品| 欧美最新免费一区二区三区| 免费黄色在线免费观看| 日韩精品有码人妻一区| 天天躁狠狠躁夜夜躁狠狠躁| 国产高清国产精品国产三级| 97精品久久久久久久久久精品| 观看av在线不卡| 日本欧美视频一区| 日本av手机在线免费观看| 免费女性裸体啪啪无遮挡网站| 久久人人爽人人片av| 亚洲国产av影院在线观看| 成人午夜精彩视频在线观看| av卡一久久| a级毛片在线看网站| 亚洲精品国产av蜜桃| 一边亲一边摸免费视频| 啦啦啦 在线观看视频| 欧美国产精品va在线观看不卡| 制服诱惑二区| 日韩视频在线欧美| 国产av国产精品国产| 满18在线观看网站| 天堂俺去俺来也www色官网| 精品久久久久久电影网| 久久久欧美国产精品| 99久久99久久久精品蜜桃| 亚洲国产欧美一区二区综合| 丝瓜视频免费看黄片| 欧美国产精品一级二级三级| 国产一卡二卡三卡精品 | 黄片小视频在线播放| 人妻人人澡人人爽人人| 欧美精品一区二区免费开放| 巨乳人妻的诱惑在线观看| 免费观看性生交大片5| 亚洲七黄色美女视频| 性色av一级| 日韩中文字幕视频在线看片| 国产在线视频一区二区| 一边摸一边抽搐一进一出视频| 欧美日韩福利视频一区二区| 国产精品香港三级国产av潘金莲 | 精品亚洲乱码少妇综合久久| 久久午夜综合久久蜜桃| 欧美日韩亚洲综合一区二区三区_| 韩国高清视频一区二区三区| 国产一区亚洲一区在线观看| 在线天堂中文资源库| 国产精品久久久久久精品电影小说| 69精品国产乱码久久久| 日韩 欧美 亚洲 中文字幕| 国精品久久久久久国模美| 国产成人精品无人区| 久久久久久久国产电影| 激情五月婷婷亚洲| 国产熟女欧美一区二区| 美女视频免费永久观看网站| 日本猛色少妇xxxxx猛交久久| 午夜福利免费观看在线| 亚洲熟女毛片儿| 各种免费的搞黄视频| 欧美日本中文国产一区发布| 水蜜桃什么品种好| 99热网站在线观看| 国产av一区二区精品久久| 午夜91福利影院| 一级片免费观看大全| 亚洲av在线观看美女高潮| 成人漫画全彩无遮挡| 久久人妻熟女aⅴ| 女人被躁到高潮嗷嗷叫费观| 国产男女内射视频| 久久国产精品大桥未久av| 在线观看www视频免费| 成人三级做爰电影| 国产成人精品在线电影| 久久精品久久久久久久性| 久久久久视频综合| 国产成人精品福利久久| 一级黄片播放器| 各种免费的搞黄视频| 岛国毛片在线播放| 国产亚洲av高清不卡| 成年女人毛片免费观看观看9 | a级毛片在线看网站| av在线app专区| 精品少妇久久久久久888优播| 欧美精品人与动牲交sv欧美| 精品人妻一区二区三区麻豆| 日韩成人av中文字幕在线观看| 欧美精品人与动牲交sv欧美| 国产日韩欧美亚洲二区| 久久青草综合色| 视频在线观看一区二区三区| 欧美精品高潮呻吟av久久| 国产成人免费无遮挡视频| 国产精品国产三级专区第一集| 日本欧美视频一区| 大片免费播放器 马上看| 亚洲美女黄色视频免费看| 精品一品国产午夜福利视频| 一级毛片我不卡| 婷婷色综合大香蕉| 久久天堂一区二区三区四区| 老司机亚洲免费影院| 日韩制服骚丝袜av| 亚洲在久久综合| 97精品久久久久久久久久精品| 狂野欧美激情性xxxx| 看十八女毛片水多多多| 啦啦啦啦在线视频资源| √禁漫天堂资源中文www|