• <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
    中文字幕熟女人妻在线| 桃红色精品国产亚洲av| 国产精品久久久人人做人人爽| 变态另类成人亚洲欧美熟女| 国产又黄又爽又无遮挡在线| 久久性视频一级片| АⅤ资源中文在线天堂| 国产极品精品免费视频能看的| 特大巨黑吊av在线直播| 99久久无色码亚洲精品果冻| 久久久久久久久大av| 亚洲成人免费电影在线观看| 人妻丰满熟妇av一区二区三区| 99精品久久久久人妻精品| 国产精品爽爽va在线观看网站| 无遮挡黄片免费观看| 手机成人av网站| 九色国产91popny在线| 麻豆成人午夜福利视频| 久久久久久大精品| 欧美av亚洲av综合av国产av| 欧美日韩精品网址| 欧美大码av| 亚洲人成电影免费在线| 日韩精品青青久久久久久| 久久伊人香网站| 久久久色成人| 国产精品精品国产色婷婷| 亚洲成人中文字幕在线播放| 欧美最新免费一区二区三区 | 亚洲av美国av| 嫩草影视91久久| 免费看光身美女| 亚洲天堂国产精品一区在线| 欧美日韩福利视频一区二区| 中文字幕熟女人妻在线| 久久精品国产自在天天线| 在线观看免费视频日本深夜| 淫妇啪啪啪对白视频| 国产美女午夜福利| 免费看美女性在线毛片视频| 国产主播在线观看一区二区| 国内精品美女久久久久久| 国产熟女xx| 蜜桃久久精品国产亚洲av| 中文乱码字字幕精品一区二区三区 | 亚洲欧美成人综合另类久久久| 成年女人看的毛片在线观看| 少妇的逼水好多| 国产91av在线免费观看| 2021少妇久久久久久久久久久| 国产高清国产精品国产三级 | 建设人人有责人人尽责人人享有的 | 日韩强制内射视频| 久久这里只有精品中国| 欧美三级亚洲精品| 免费看不卡的av| 丝瓜视频免费看黄片| 人妻少妇偷人精品九色| 两个人视频免费观看高清| 国产欧美另类精品又又久久亚洲欧美| 神马国产精品三级电影在线观看| 精品酒店卫生间| 一级毛片aaaaaa免费看小| 美女高潮的动态| 插阴视频在线观看视频| 青春草亚洲视频在线观看| 国产精品久久久久久精品电影| 日韩人妻高清精品专区| 网址你懂的国产日韩在线| 国产色婷婷99| 特大巨黑吊av在线直播| 男人爽女人下面视频在线观看| 狂野欧美激情性xxxx在线观看| 精品国产三级普通话版| 国产精品综合久久久久久久免费| 国产探花极品一区二区| 国产一区有黄有色的免费视频 | av专区在线播放| 熟妇人妻不卡中文字幕| 人妻少妇偷人精品九色| 一个人观看的视频www高清免费观看| 高清av免费在线| 国内揄拍国产精品人妻在线| 日韩人妻高清精品专区| 夫妻性生交免费视频一级片| 午夜免费男女啪啪视频观看| 精品久久久久久久久久久久久| 久久精品国产亚洲网站| 午夜免费激情av| 搡老妇女老女人老熟妇| 少妇的逼好多水| 婷婷六月久久综合丁香| 汤姆久久久久久久影院中文字幕 | 少妇人妻一区二区三区视频| 精品一区二区三区人妻视频| 欧美不卡视频在线免费观看| 秋霞伦理黄片| 尤物成人国产欧美一区二区三区| 少妇人妻精品综合一区二区| 精品久久久精品久久久| 免费看美女性在线毛片视频| 一本—道久久a久久精品蜜桃钙片 精品乱码久久久久久99久播 | 内地一区二区视频在线| 好男人视频免费观看在线| 国产精品日韩av在线免费观看| 亚洲怡红院男人天堂| 黄片无遮挡物在线观看| 两个人的视频大全免费| 亚洲av二区三区四区| 免费av观看视频| 国产成人精品一,二区| 99久国产av精品| 国产黄色视频一区二区在线观看| 97热精品久久久久久| 深爱激情五月婷婷| 国产成人福利小说| 国产一区二区在线观看日韩| 亚洲av国产av综合av卡| 日本免费在线观看一区| 色综合色国产| 国产成人一区二区在线| 国产伦精品一区二区三区四那| 国产综合懂色| 欧美极品一区二区三区四区| 国产乱来视频区| 在线免费十八禁| 最近手机中文字幕大全| 日韩av在线大香蕉| 欧美一区二区亚洲| 97在线视频观看| 亚洲av福利一区| 国产精品一及| eeuss影院久久| 亚洲自拍偷在线| 国产黄色免费在线视频| 国产高潮美女av| av.在线天堂| 美女脱内裤让男人舔精品视频| 免费看光身美女| 久久久久免费精品人妻一区二区| 国产色婷婷99| 男女那种视频在线观看| 别揉我奶头 嗯啊视频| 欧美 日韩 精品 国产| 国产亚洲一区二区精品| 非洲黑人性xxxx精品又粗又长| 精品一区二区三区视频在线| 欧美xxxx黑人xx丫x性爽| 欧美激情在线99| 校园人妻丝袜中文字幕| 听说在线观看完整版免费高清| 亚洲精品色激情综合| av免费在线看不卡| 日韩不卡一区二区三区视频在线| 日本午夜av视频| 日本色播在线视频| 人人妻人人澡欧美一区二区| 91午夜精品亚洲一区二区三区| 永久免费av网站大全| 亚洲欧美一区二区三区黑人 | 亚洲自偷自拍三级| 人体艺术视频欧美日本| 高清视频免费观看一区二区 | 亚洲精品自拍成人| 天天躁夜夜躁狠狠久久av| 纵有疾风起免费观看全集完整版 | 日韩不卡一区二区三区视频在线| av国产免费在线观看| 美女大奶头视频| 国产精品福利在线免费观看| 国产av在哪里看| 日产精品乱码卡一卡2卡三| 国产精品一区二区性色av| 精品熟女少妇av免费看| 全区人妻精品视频| 精品国产一区二区三区久久久樱花 | 天堂av国产一区二区熟女人妻| 免费观看精品视频网站| 亚洲av成人精品一区久久| 在线观看人妻少妇| 观看免费一级毛片| 免费黄频网站在线观看国产| 亚洲av在线观看美女高潮| 亚洲不卡免费看| 直男gayav资源| 亚洲精品一区蜜桃| 亚洲图色成人| 精品人妻一区二区三区麻豆| 国产成人一区二区在线| 国产精品久久久久久久电影| 中文欧美无线码| 亚洲精品国产成人久久av| 80岁老熟妇乱子伦牲交| 网址你懂的国产日韩在线| 男人舔奶头视频| 国产视频首页在线观看| 亚洲成人久久爱视频| 五月天丁香电影| 99热全是精品| 成人二区视频| 特大巨黑吊av在线直播| 别揉我奶头 嗯啊视频| 乱码一卡2卡4卡精品| 日韩电影二区| 精品国内亚洲2022精品成人| 最近中文字幕2019免费版| 亚洲av男天堂| 最近手机中文字幕大全| 超碰97精品在线观看| 久久韩国三级中文字幕| 国产精品人妻久久久影院| 婷婷六月久久综合丁香| 日韩伦理黄色片| 久久久久久久久大av| 国产黄a三级三级三级人| 最近视频中文字幕2019在线8| 日日干狠狠操夜夜爽| 亚洲va在线va天堂va国产| 五月天丁香电影| 免费在线观看成人毛片| 久久久久久久国产电影| 亚洲av成人精品一区久久| 久久久欧美国产精品| 精品酒店卫生间| 国内精品美女久久久久久| 日产精品乱码卡一卡2卡三| 男女下面进入的视频免费午夜| 亚洲精品乱久久久久久| 一级a做视频免费观看| 天美传媒精品一区二区| 国语对白做爰xxxⅹ性视频网站| 国产精品嫩草影院av在线观看| 麻豆精品久久久久久蜜桃| 欧美成人午夜免费资源| 日韩电影二区| 国产成人freesex在线| 国产男女超爽视频在线观看| 日韩欧美 国产精品| 精华霜和精华液先用哪个| 一本—道久久a久久精品蜜桃钙片 精品乱码久久久久久99久播 | 一个人看视频在线观看www免费| 波野结衣二区三区在线| 国产爱豆传媒在线观看| www.色视频.com| 夫妻午夜视频| 国产免费视频播放在线视频 | 插逼视频在线观看| 亚洲精品久久久久久婷婷小说| 热99在线观看视频| 有码 亚洲区| 欧美zozozo另类| av女优亚洲男人天堂| 久久草成人影院| 精品久久久噜噜| 天天一区二区日本电影三级| 国产午夜福利久久久久久| 久久99蜜桃精品久久| 国产精品久久久久久精品电影| 激情五月婷婷亚洲| 一个人观看的视频www高清免费观看| 五月天丁香电影| 特大巨黑吊av在线直播| 免费观看精品视频网站| 看免费成人av毛片| 中文天堂在线官网| 日韩不卡一区二区三区视频在线| 夫妻午夜视频| 午夜福利在线观看吧| 少妇熟女欧美另类| 最近最新中文字幕大全电影3| 人妻一区二区av| av天堂中文字幕网| 亚洲真实伦在线观看| 国产 亚洲一区二区三区 | 国产一区二区亚洲精品在线观看| 亚洲国产精品成人综合色| 欧美xxxx性猛交bbbb| 又黄又爽又刺激的免费视频.| 熟妇人妻久久中文字幕3abv| 精品一区二区三区人妻视频| 国产不卡一卡二| 国产精品三级大全| 国产精品久久视频播放| 天堂俺去俺来也www色官网 | 全区人妻精品视频| 国产 一区精品| 男女边吃奶边做爰视频| 亚洲国产最新在线播放| 亚洲成人一二三区av| 欧美97在线视频| .国产精品久久| 亚洲成人精品中文字幕电影| 中文精品一卡2卡3卡4更新| 卡戴珊不雅视频在线播放| 国产中年淑女户外野战色| 男女那种视频在线观看| 国产成人精品福利久久| 亚洲av中文av极速乱| 亚洲精品乱久久久久久| 69av精品久久久久久| 久久精品国产亚洲网站| 国产激情偷乱视频一区二区| 搞女人的毛片| 精品人妻偷拍中文字幕| 免费电影在线观看免费观看| 国产av国产精品国产| 三级国产精品片| 国产探花在线观看一区二区| 国产男女超爽视频在线观看| 久久国产乱子免费精品| 91久久精品国产一区二区三区| 一本久久精品| 精品久久久久久成人av| 亚洲性久久影院| 亚洲国产精品sss在线观看| 色综合站精品国产| 亚洲av免费高清在线观看| 亚洲av在线观看美女高潮| 国产伦一二天堂av在线观看| 国产永久视频网站| av又黄又爽大尺度在线免费看| 亚洲婷婷狠狠爱综合网| 晚上一个人看的免费电影| 中文字幕av在线有码专区| 国产精品一区二区性色av| 亚洲美女视频黄频| 免费观看性生交大片5| 男人和女人高潮做爰伦理| 国产精品美女特级片免费视频播放器| 天堂影院成人在线观看| 免费无遮挡裸体视频| 美女主播在线视频| 综合色丁香网| 久久精品久久久久久久性| 国产精品人妻久久久久久| 国产爱豆传媒在线观看| 又粗又硬又长又爽又黄的视频| 男插女下体视频免费在线播放| 国产乱人偷精品视频| 一个人看的www免费观看视频| av国产免费在线观看| 少妇裸体淫交视频免费看高清| 国产成人aa在线观看| 成人一区二区视频在线观看| 精品一区二区三区人妻视频| 最近最新中文字幕免费大全7| 亚洲婷婷狠狠爱综合网| 高清毛片免费看| 人人妻人人澡人人爽人人夜夜 | 久久99热这里只频精品6学生| 国产乱来视频区| 亚洲欧美日韩东京热| 97人妻精品一区二区三区麻豆| av又黄又爽大尺度在线免费看| 日本免费a在线| 国产黄色视频一区二区在线观看| 老女人水多毛片| 国产乱人视频| 日韩av在线大香蕉| 99热这里只有是精品50| 天堂中文最新版在线下载 | 成人午夜精彩视频在线观看| 人人妻人人澡人人爽人人夜夜 | 久久精品久久久久久噜噜老黄| 欧美精品国产亚洲| 亚洲aⅴ乱码一区二区在线播放| 水蜜桃什么品种好| 高清毛片免费看| 久久久久免费精品人妻一区二区| 亚洲欧美精品自产自拍| 亚洲精品成人久久久久久| 色哟哟·www| 一本久久精品| 女的被弄到高潮叫床怎么办| 欧美变态另类bdsm刘玥| 日本免费在线观看一区| 日韩中字成人| 狂野欧美激情性xxxx在线观看| 美女cb高潮喷水在线观看| 天堂俺去俺来也www色官网 | 国产精品人妻久久久久久| 青春草视频在线免费观看| 日韩一区二区视频免费看| 国产高潮美女av| 亚洲熟妇中文字幕五十中出| 最近手机中文字幕大全| 啦啦啦中文免费视频观看日本| 日韩 亚洲 欧美在线| 日本一本二区三区精品| 国产熟女欧美一区二区| 日韩不卡一区二区三区视频在线| 天天躁日日操中文字幕| 亚洲不卡免费看| 国产精品99久久久久久久久| 国产极品天堂在线| 嫩草影院新地址| 亚洲精品中文字幕在线视频 | 免费av不卡在线播放| 免费观看a级毛片全部| 最近视频中文字幕2019在线8| 亚洲精品成人av观看孕妇| 亚洲欧洲日产国产| 欧美日韩一区二区视频在线观看视频在线 | 午夜免费男女啪啪视频观看| 国产av码专区亚洲av| 欧美日韩在线观看h| a级毛片免费高清观看在线播放| 欧美xxxx黑人xx丫x性爽| 久久精品久久久久久久性| 亚洲,欧美,日韩| 久久精品久久久久久噜噜老黄| 日日摸夜夜添夜夜爱| 亚洲图色成人| 在现免费观看毛片| 日韩电影二区| 汤姆久久久久久久影院中文字幕 | 一区二区三区免费毛片| 国产在线一区二区三区精| 波野结衣二区三区在线| 久久久久久伊人网av| 毛片女人毛片| 成年女人在线观看亚洲视频 | 久久精品国产自在天天线| 卡戴珊不雅视频在线播放| 久久精品熟女亚洲av麻豆精品 | 我要看日韩黄色一级片| 久久久a久久爽久久v久久| 身体一侧抽搐| 国产国拍精品亚洲av在线观看| 好男人在线观看高清免费视频| 免费黄频网站在线观看国产| 欧美日韩综合久久久久久| 亚洲精品色激情综合| 免费在线观看成人毛片| 久久久久免费精品人妻一区二区| 亚洲精品自拍成人| 久久久精品欧美日韩精品| 韩国高清视频一区二区三区| 亚洲国产日韩欧美精品在线观看| av在线观看视频网站免费| 少妇裸体淫交视频免费看高清| 久久草成人影院| 欧美激情久久久久久爽电影| 日韩伦理黄色片| 欧美日韩国产mv在线观看视频 | 寂寞人妻少妇视频99o| 爱豆传媒免费全集在线观看| 男人和女人高潮做爰伦理| 国产色婷婷99| 久久热精品热| 一级毛片久久久久久久久女| 亚洲av电影不卡..在线观看| 人人妻人人澡人人爽人人夜夜 | 国产高清国产精品国产三级 | 日韩,欧美,国产一区二区三区| 欧美日韩精品成人综合77777| 女人十人毛片免费观看3o分钟| 欧美高清性xxxxhd video| 人体艺术视频欧美日本| 亚洲精品色激情综合| 成人性生交大片免费视频hd| 人人妻人人看人人澡| 亚洲欧美精品专区久久| 69av精品久久久久久| 午夜久久久久精精品| 精品一区二区三区人妻视频| 一级毛片电影观看| 天堂俺去俺来也www色官网 | 大话2 男鬼变身卡| 男女国产视频网站| 久久人人爽人人片av| 国产一区二区三区综合在线观看 | 色综合色国产| 日日撸夜夜添| 在线免费十八禁| 国产一区二区三区综合在线观看 | 国产乱人视频| 两个人视频免费观看高清| 丝袜喷水一区| 国产亚洲5aaaaa淫片| 亚洲婷婷狠狠爱综合网| 成年女人在线观看亚洲视频 | 亚洲精品aⅴ在线观看| 在线观看美女被高潮喷水网站| 亚洲精品一区蜜桃| 身体一侧抽搐| 国产黄色小视频在线观看| 老师上课跳d突然被开到最大视频| 永久免费av网站大全| 国产精品久久久久久av不卡| 久久久欧美国产精品| 精品久久久久久电影网| 建设人人有责人人尽责人人享有的 | 伦精品一区二区三区| 国产精品人妻久久久影院| 如何舔出高潮| 日韩一本色道免费dvd| 久久午夜福利片| 国产伦一二天堂av在线观看| 亚洲熟妇中文字幕五十中出| 国产91av在线免费观看| 日日啪夜夜撸| 日本一二三区视频观看| 看免费成人av毛片| or卡值多少钱| 欧美97在线视频| 精品国产三级普通话版| 99热6这里只有精品| 永久网站在线| 天天躁日日操中文字幕| 亚洲,欧美,日韩| 男女边吃奶边做爰视频| 老师上课跳d突然被开到最大视频| 亚洲国产精品专区欧美| 别揉我奶头 嗯啊视频| 看非洲黑人一级黄片| 免费看日本二区| 国产 一区精品| 三级国产精品片| 一区二区三区高清视频在线| 亚洲欧美日韩卡通动漫| 亚洲人成网站在线观看播放| 在线免费观看的www视频| 18禁动态无遮挡网站| 三级男女做爰猛烈吃奶摸视频| 超碰av人人做人人爽久久| 国产伦理片在线播放av一区| 狂野欧美激情性xxxx在线观看| 国产在线男女| 激情五月婷婷亚洲| 日韩一区二区视频免费看| 日本猛色少妇xxxxx猛交久久| 欧美97在线视频| 久久人人爽人人爽人人片va| 日韩视频在线欧美| 亚洲av福利一区| 亚洲国产成人一精品久久久| 日韩av不卡免费在线播放| 男人和女人高潮做爰伦理| 欧美三级亚洲精品| 高清欧美精品videossex| 一级毛片黄色毛片免费观看视频| 18禁在线无遮挡免费观看视频| 国产精品.久久久| 中国国产av一级| 日韩欧美一区视频在线观看 | 日本与韩国留学比较| 女人十人毛片免费观看3o分钟| 真实男女啪啪啪动态图| 国产精品综合久久久久久久免费| 日韩强制内射视频| 欧美高清性xxxxhd video| 身体一侧抽搐| 欧美性感艳星| 久久久久久久久久久丰满| 日韩欧美 国产精品| 日韩成人av中文字幕在线观看| 精品亚洲乱码少妇综合久久| 永久网站在线| 国产精品精品国产色婷婷| 蜜桃久久精品国产亚洲av| 成人毛片60女人毛片免费| 视频中文字幕在线观看| videos熟女内射| 欧美精品一区二区大全| 欧美zozozo另类| 日韩一区二区视频免费看| 日本wwww免费看| 久久精品国产亚洲网站| 国产精品1区2区在线观看.| 日韩强制内射视频| 亚洲人成网站高清观看| 欧美日韩精品成人综合77777| 亚洲av电影不卡..在线观看| 精品国产三级普通话版| 国产久久久一区二区三区| 亚洲国产精品专区欧美| 国产综合懂色| 久久人人爽人人爽人人片va| 国产欧美日韩精品一区二区| 国产高清国产精品国产三级 | 成人无遮挡网站| av在线蜜桃| 综合色丁香网| 亚洲三级黄色毛片| 精品久久久久久久久亚洲| 麻豆乱淫一区二区| 成人毛片60女人毛片免费| 一级二级三级毛片免费看| 简卡轻食公司| 精品国产露脸久久av麻豆 | 别揉我奶头 嗯啊视频| 色吧在线观看| 大又大粗又爽又黄少妇毛片口| 在线免费观看的www视频| 青春草视频在线免费观看| 国国产精品蜜臀av免费| 欧美日本视频| 久久精品久久精品一区二区三区| 久久久久国产网址| 午夜福利在线观看吧| 精品熟女少妇av免费看| 成人性生交大片免费视频hd| freevideosex欧美| 欧美成人精品欧美一级黄| 国产精品av视频在线免费观看| 在线观看人妻少妇| 男女边吃奶边做爰视频| 国产精品99久久久久久久久| 国产在视频线精品| 久久久久久九九精品二区国产| 久99久视频精品免费| 免费观看av网站的网址| 插阴视频在线观看视频|