• <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 ?

    Raman lasing and other nonlinear effects based on ultrahigh-Q CaF2 optical resonator

    2022-10-26 09:49:24TongXing邢彤EnboXing邢恩博TaoJia賈濤JianglongLi李江龍JiaminRong戎佳敏YanruZhou周彥汝WenyaoLiu劉文耀JunTang唐軍andJunLiu劉俊
    Chinese Physics B 2022年10期
    關(guān)鍵詞:劉俊江龍唐軍

    Tong Xing(邢彤), Enbo Xing(邢恩博), Tao Jia(賈濤), Jianglong Li(李江龍), Jiamin Rong(戎佳敏),Yanru Zhou(周彥汝), Wenyao Liu(劉文耀), Jun Tang(唐軍), and Jun Liu(劉俊)

    Key Laboratory of Electronic Testing Technology,School of Instrument and Electronics,North University of China,Taiyuan 030051,China

    Keywords: whispering gallery mode, crystalline resonator, Raman lasing, nonlinear effects, thermo-optical oscillation,optical frequency combs

    1. Introduction

    Achieving efficient nonlinear optical interactions at low optical power has always been one of the main goals of nonlinear optics.[1–5]Various nonlinear optical effects,such as frequency doubling,[6]frequency mixing,[7]Raman scattering,[8,9]Brillouin scattering,[10]and other effects[11]have broad prospects in optical computing, quantum information processing, precision spectroscopy, optical communication, biological imaging, and many other fields.[12,13]The whispering gallery mode (WGM) resonators are fabricated with a variety of materials including silicon, sapphire, fused silica,fluoride crystalline, lithium ninobate, and other optical glasses. Owing to their ultrahigh quality(Q)factor and small mode volume, optical resonators significantly enhance lightmatter interactions and establish extremely high circulating intracavity intensities, thereby reducing the pump threshold for nonlinear processes. The frequency conversion of the pump light can also be achieved at low power, so the optical resonator becomes an ideal platform to study various nonlinear effects.[14–16]

    Recently, fluoride crystals, such as calcium fluoride(CaF2), magnesium fluoride (MgF2),[17]barium fluoride(BaF2),[18]and strontium fluoride(SrF2)[19]have been equally demonstrated to have ultrahighQin the near-IR, such an ultrahighQattracts extremely great attention in various research fields.[20–22]Another advantage of crystalline materials for the fabrication of the resonators is that they can be stable against humidity, and do not degradeQwhen exposed to atmospheric water vapor. A CaF2resonator withQ >1011at 1550 nm has been fabricated and reported.[23]Such an ultrahighQgreatly reduces the excitation threshold of nonlinear effects in the resonator,and it is easy to obtain laser emission based on nonlinear effects even in materials without significant nonlinearity.[24–26]Therefore, the CaF2resonator with ultrahighQ,small mode volume,high stability,and low noise interference has become the best choice for nonlinear optical applications.[27,28]

    Here, we theoretically analyze the Raman threshold of the CaF2resonator, and obtain the relationship betweenQ,mode volume (Vm) of the resonator, and the Raman threshold. Meanwhile, we experimentally demonstrate Raman lasing, first-order Raman comb, and the second-order Raman lasing in a millimeter size CaF2WGM disk resonator with ultrahigh-Qfactor of 8.43×108at 1550 nm. We also report the observation and characterization of thermal effects due to the negative thermo-optic coefficient and the positive thermo-expansion coefficient. At the same time, the threshold for thermo-optical oscillation is approximately coincident with Raman lasing.With a further increase in pump power,the optical frequency combs range is from 1520 nm to 1650 nm,with a wavelength interval of 4×FSR. And the adjustment of the optical frequency combs can be realized by using the frequency tuning of the pump light,which have great applications in optical communication,biological environment monitoring,spectral analysis,and microwave signal sources.

    2. Theoretical analysis and discussion

    For the first-order Raman lasing output in the optical resonator,the coupled mode equation is established,which is expressed as

    whereEpandERare the pump light energy and stimulated Raman laser energy, respectively,cis the speed of light,neffis the effective refractive index of the resonator,ωpandωRare the pump light frequency and the stimulated Raman laser frequency, respectively, andgR=2.4×10-13m/W[22]is the Raman gain coefficient of the CaF2resonator.

    The mode volume (Vm) of the CaF2resonator is defined as the ratio of the full-space integral of the mode field energy density to the maximum energy density,and is expressed as

    whereE(r) is the electric field vector,n2(r)|E(r)|2is the energy density at a point in the resonator. TheVmaffects the energy density of the WGM in the resonator. A smaller mode volume corresponds to a larger energy density, which enhances the interaction between light and matter and is beneficial to lowering the threshold of nonlinear effects.

    The basis of Raman laser is stimulated Raman scattering which is a process of obtaining Raman gain in materials through nonlinear effects. In the process of stimulated Raman scattering, photons with red-shifted and blue-shifted frequencies are generated. The lasing threshold occurs when cavity round-trip gain equals round-trip loss. For an intensitydependent gain coefficient,the minimum Raman threshold can be simplified as[21]

    whereλpandλRare the pump light wavelength and the stimulated Raman laser wavelength,respectively,n=1.426 is the refractive index of the CaF2resonator,QPandQRare quality factors for the pump and Raman wavelengths,respectively,andVmis the mode volume. If theQfactor is the same for pump and Raman wavelengths, the Raman threshold is proportional to the ratioVm/Q2. Thus, the low Raman lasing threshold and efficient cascaded operation is made possible by the ultrahigh-Qof the WGM crystalline resonator.

    According to Eq. (4), the relationship between the Raman threshold and theQand theVmcan be obtained. It can be seen from Fig.1 thatQis inversely proportional to the Raman threshold,that is,asQincreases,the Raman threshold gradually decreases;theVmis proportional to the Raman threshold,that is, as the mode volume decreases, the Raman threshold decreases.Therefore,choosing a ultrahigh-Q,small mode volume CaF2resonator can further reduce the Raman threshold.

    Fig. 1. Relationship between mode volume and Q of CaF2 resonator and power threshold for Raman laser generation.

    3. Experimental results and discussion

    3.1. Experimental setup and characterization

    The experimental setup shown in Fig.2(a)is used to characterize the Raman lasing and other nonlinear effects based on the CaF2resonator system. A continuous-wave tunable laser(DLC pro)around 1550 nm with a linewidth of 10 kHz passes through the isolator and enters the CaF2resonator via the fibertaper. The wavelength of the laser is scanned by signal generator (SG) to obtain the transmission spectrum for characterization of the resonator. The fiber-baser polarization controller(PC)is used to optimize the coupling strength.The light out of the fiber taper is connected with the beam splitter to the lownoise photodetector(PD)and wavelength division multiplexer(WDM) respectively. PD convert optical signals into electrical signals and then connect to oscilloscopes (OSC) for data acquisition and analysis processing. The WDM separates the pump laser and the Raman laser,and then connects them to the optical spectrum analyzer(OSA)for display. The CaF2crystalline WGM resonator is fabricated by single point diamond cutting and mechanical polishing method. The radius of the CaF2resonator is 2.48 mm, the thickness is 0.5 mm and the shape of cylinder blanks. The tapered fiber with the diameter of about 2 μm serves as the input and output ports, and the coupling to the CaF2resonator is accomplished by evanescent field coupling using a nano-positioning system. Figure 2(b)is the schematic diagram of fiber coupling in CaF2resonator.Figure 2(c) is the calculatedQfactor for CaF2resonator of 8.43×108and remains stable under normal atmospheric conditions. Once inside the clean room environment or vacuum,theQcan be preserved on a very high level for indefinite amount of time, for which our experiments are conducted in the clean room.

    Fig.2. (a)Diagram of the measurement setup for characterizing the nonlinear optical processes based on high-Q CaF2 optical resonator. (b)Schematic diagram of fiber coupling in CaF2 resonator. (c) The calculated Q for CaF2 resonator of 8.43×108. DLC: pro continuous-wave tunable laser, PC: polarization controller, EDFA: erbium-doped fiber amplifier, PD: photodetector, OSC: oscilloscope, SG: signal generator,OSA:optical spectrum analyzer,WDM:wavelength division multiplexer.

    3.2. Raman lasing measurement

    For Raman lasing measurement,the pump wavelength is 1550.58 nm, and the pump power gradually increases from 100 μW. When the pump power is increased to 33 mW, the first-order Raman laser with the signal to noise ratio(SNR)of 46 dB is observed on the optical spectrum analyzer,as shown in Fig. 3(a). Similarly, when the pump power is gradually increased to 36 mW, the first-order Raman comb appears in Fig.3(b)and the second-order Raman lasing appears when the pump power is increased to 45 mW in Fig.3(c).Raman combs result from the delayed molecular response of the host medium to the laser excitation. Thanks to the low lasing threshold,the first Stokes radiation to longer wavelengths is feasible,resulting in Raman combs. By further enhancing the pump power,the intracavity first Stokes power will be sufficiently high to act as a secondary pump source to enable the second Stokes lasing at 1722.19 nm, as shown in Fig. 3(c). The transition from Fig.3(b)to Fig.3(c)is because the energy coupling from the side modes to the second Stokes,when the second Stokes existed. Since the side modes has lower gain than that of the central mode,so only the central mode survived.[29]

    Fig.3. Observation of cascaded Raman lasing and threshold measurement. (a)First-order Raman lasing at 1631.59 nm. (b)First-order Raman comb generation. (c)Second-order Raman lasing generation. (d)Raman output power as a function of the pump power based on a diameter of 4.96-mm resonator.

    In order to measure the Raman threshold,we plot the Raman output power as a function of pump power in Fig. 3(d).The measurement shows a linear dependency and indicates the pump power threshold is 30 mW for a diameter of 4.96-mm CaF2resonator. We also plot the relationship between the pump power and the cavity absorbed power, as shown in the inset of Fig. 3(d). The actual power entering the resonator is only 9.68%of the pump power, the calculated conversion efficiency is about 5.27%. The power of the Raman lasing peak seems very low is because the attenuator is connected before connecting to the OSA during the experiment. The first-order Raman comb threshold pump power is 36 mW,and the secondorder Raman lasing is 45 mW.The reasons for the low conversion efficiency mainly include the following aspects: (i) the detuning loss caused by the frequency scanning of the pump laser;(ii)the loss at the connection of various devices;(iii)in our experiment, we use the ‘zero-gap’ coupling state, that is,the tapered fiber is attached to the surface of the resonator,the influence of environmental fluctuation noise is suppressed,but reduces theQ.

    Since Raman lasing threshold is proportional toVm/Q2,mode volume to quality factor squared ratio,it is natural to expect improvements in efficiency and threshold for a cavity with higherQfactor. The higher theQ(theoreticalQ ≈1014)and the smaller the mode volume(V-shaped),the lower the Raman threshold(a few μW),so that the crystalline WGM resonators can become efficient and compact Raman converters. Next,we will prepare V-shaped resonator to further reduce the mode volume and thus lower the Raman threshold.

    3.3. Thermal effect and Raman laser

    When the input power increases above 30 mW, a strong heat accumulation occurs inside the resonator, resulting in thermal effect. The heat generated by the absorbed optical power in the mode volume elevates the temperature very rapidly. As the cavity temperature varies,neffandRchange due to the thermo-optic (TO) effect (dn/dT=-1.14×10-5K-1) and thermal expansion (TE) effect (dR/RdT=1.87×10-5K-1), respectively, giving rise to the resonance shift. While taking the direction of the wavelength shift into consideration,we scan the pump laser wavelength in the long to short wavelength direction. The scanning voltage of the laser is 1.5 V,and the scanning frequency is 10 Hz,as shown in the upper picture of Fig.4(a). When the pump light scans into the resonant peak in the long wavelength direction, the thermal effect will push the resonant peak to move in the opposite direction due to the negative TO effect, and the compressed resonant peak will be obtained on the transmission spectrum.On the contrary,when the pump light scans to the short wavelength and enters the resonant peak, the pump light will stay in the resonant peak for a long time,and a broadened resonant peak will be obtained in the transmission spectrum,as shown in the lower picture of Fig.4(a).

    Fig.4. (a)Thermal nonlinear effects in CaF2 resonator. (b)The pump laser and Raman laser from the WDM on the OSC.

    Figure 4(b) uses the wavelength division multiplexer(WDM) to separate the pump laser and the Raman laser, and then connect them to the oscilloscope for simultaneous observation. CaF2resonator has a negative TO coefficient and a positive TE coefficient,these two parameters will cause completely opposite changes in the resonance wavelength, resulting in the fluctuation of the intracavity power, so the output light field exhibits periodic oscillation,that is,thermo-optical oscillation can be generated,as shown in the lower picture of Fig.4(b). When the power reaches the threshold,the intracavity power increases rapidly, the Raman emission power turns into laser oscillation. A higher input pump power results in a longer thermal drift and a higher Raman emission power while the threshold coupled power is maintained. However,different modes have differentQand require different pump power to generate thermal effects. When the pump power is greater than 30 mW, the mode with higherQwill first generate thermo-optic oscillation, while the mode with lowerQdoes not observe the phenomenon,that is,the relatively lowerQdoes not generate Raman laser accordingly. Furthermore,thermal broadening and thermal compression occur in pairs,located on the left and right sides of the triangular wave, respectively. In order to see the paired phenomenon more intuitively, we added triangular waves in Fig. 4(b). And in the experiment,the threshold for generating thermo-optical oscillation is also 30 mW, that is, Raman lasing is always accompanied by thermo-optical oscillations. It was found that the threshold for the oscillations is approximately coincident with Raman lasing threshold.

    3.4. Other nonlinear effects

    As the pump power increases,the energy will be concentrated in the ultrahigh-Qresonator, the resonant frequency of the resonator and the detuning of the pump light will reach a balance point, and then the degenerate four-wave mixing(FWM)effect will appear.Further broadening of the FWM results in an optical frequency combs. When the power reaches the threshold,the intracavity power increases rapidly because the Kerr effect causes a rapid redshift of the resonance wavelength. The wavelength of the pump light power is set to 1550 nm, when the input power is set to 80 mW, after the energy is accumulated in the resonator,the primary comb are generated due to the FWM effect. Since the pump power energy is high enough,the energy in the resonator is further accumulated, and the secondary combs appears due to the cascaded FWM effect.The wavelength range of optical frequency comb extends from 1520 nm to 1650 nm and exceeds 120 nm,as shown in Fig.5(a).

    The pump wavelength is swept from short to long wavelengths while gradually increasing the power from 100 μW to 80 mW. When a sideband appears near the pump wavelength, stop increasing the pump power, detuning the pump wavelength from blue to the resonance peak, and observe the change of the comb teeth. At this time, several symmetrical spectrum lines appear around the pump wavelength,which are mainly composed of multiple FSRs. When the pump wavelength gradually approaches the resonance peak from blue detuning, the main combs have strong sideband effects and excite regular and gradually denser secondary combs. With the further reduction of the detuning amount of the pump wavelength, the sideband effect continues to strengthen, and more spectrum can be generated. The secondary combs next to the main comb continue to expand,the spectrum becomes denser,and finally an optical frequency comb is formed. The modulation of the optical frequency combs can be achieved by using the frequency tuning of the pump light.

    The power and mode spacing of the optical frequency comb are not uniform, which is caused by the changed temperature of the resonator absorbed optical power and the existence of abundant resonance modes in the CaF2resonator,and the interaction between different modes. This temperature change leads to a modification of the refractive index of calcium fluoride which affects the optical path length of the resonator modes. In order to reduce the influence on the optical frequency comb,it is necessary to improve the fabrication process and continuously modify the shape to prepare a V-type crystal resonator. In addition, the mutual coupling of other nonlinear effects and the optical frequency comb effect will also produce some burrs,thus affecting the comb mode spacing. Therefore, it is necessary to precisely control the power to reduce the influence of other nonlinear effects in the experiment.

    Fig.5.(a)Optical frequency combs with wavelength range from 1520 nm to 1650 nm in CaF2 resonator.(b)The influence of frequency tuning on optical frequency combs.

    4. Conclusion

    In conclusion, we theoretically analyzed the Raman threshold of the CaF2resonator, and obtained theQis inversely proportional to the Raman threshold,the mode volume(Vm) of the resonator is proportional to the Raman threshold,therefore,choosing an ultrahighQ,small mode volume CaF2resonator can further reduce the Raman threshold.Meanwhile,we experimentally demonstrated Raman lasing,first-order Raman comb,and the second-order Raman lasing in a CaF2disk resonator with a diameter of 4.96 mm and an ultrahighQof 8.43×108at 1550-nm wavelength. At the same time,we also observed thermal effects in CaF2disk resonators,and obtained the threshold for thermo-optical oscillations is approximately coincident with Raman lasing. With a further increase in pump power,we observed optical frequency combs with wavelengths from 1520 nm to 1650 nm,with the range greater than 120 nm and a wavelength interval of 4×FSR. This work provides a comprehensive understanding of the Raman lasing and other nonlinear effects,which has great applications in optical communication, biological environment monitoring, spectral analysis,and microwave signal sources.

    Acknowledgements

    Project supported by the National Natural Science Foundation of China(Grant Nos.51727808,51922009,52005457,and 62004179) and the Fund from the Key Laboratory of Quantum Sensing and Precision Measurement of Shanxi Province,China(Grant No.201905D121001).

    猜你喜歡
    劉俊江龍唐軍
    創(chuàng)新企業(yè)民主管理途徑的探索
    劉俊
    唐軍治療圍絕經(jīng)期失眠經(jīng)驗(yàn)總結(jié)
    Unpinning the spiral waves by using parameter waves*
    美食鑒定師
    In fluence of Ni/Mn ratio on magnetostructural transformation and magnetocaloric effect in Ni48?x Co2Mn38+x Sn12(x=0,1.0,1.5,2.0, and 2.5)ferromagnetic shape memory alloys?
    我和你打個(gè)賭
    唐軍 留守少年的逆襲
    江龍出口斯里蘭卡19.5米鋼鋁引航船順利下水
    廣東造船(2014年3期)2014-04-29 10:32:09
    江龍為廣東省水利廳建造的43.2m鋼鋁執(zhí)法船成功交付
    廣東造船(2014年3期)2014-04-29 10:32:09
    亚洲欧美色中文字幕在线| 欧美激情极品国产一区二区三区| 日韩人妻精品一区2区三区| 最新在线观看一区二区三区 | 成人三级做爰电影| 99久久99久久久精品蜜桃| 飞空精品影院首页| 宅男免费午夜| 国产黄色免费在线视频| 欧美少妇被猛烈插入视频| 色婷婷久久久亚洲欧美| 999久久久国产精品视频| 国产成人一区二区在线| 亚洲av国产av综合av卡| 搡老乐熟女国产| 亚洲国产精品成人久久小说| avwww免费| 制服丝袜香蕉在线| 国产精品秋霞免费鲁丝片| 午夜免费鲁丝| 国产精品蜜桃在线观看| 大香蕉久久网| 99精品久久久久人妻精品| 久久人人爽av亚洲精品天堂| 婷婷色av中文字幕| 欧美日本中文国产一区发布| 波多野结衣一区麻豆| 久久久久人妻精品一区果冻| 天堂俺去俺来也www色官网| 成人午夜精彩视频在线观看| 亚洲精品视频女| 美女扒开内裤让男人捅视频| 水蜜桃什么品种好| 亚洲人成网站在线观看播放| 交换朋友夫妻互换小说| xxx大片免费视频| 中文字幕精品免费在线观看视频| 在线观看人妻少妇| 国产高清不卡午夜福利| 操出白浆在线播放| 热re99久久国产66热| 欧美日韩亚洲高清精品| 久久久国产精品麻豆| 99精品久久久久人妻精品| av在线播放精品| 欧美亚洲日本最大视频资源| 色94色欧美一区二区| 国产一区二区三区av在线| 伦理电影免费视频| 婷婷成人精品国产| 成人亚洲精品一区在线观看| 久久久久视频综合| 亚洲欧美一区二区三区国产| 亚洲精品一二三| 日韩一本色道免费dvd| 又粗又硬又长又爽又黄的视频| 高清欧美精品videossex| 十八禁高潮呻吟视频| 免费高清在线观看日韩| 国产亚洲欧美精品永久| 国语对白做爰xxxⅹ性视频网站| 九九爱精品视频在线观看| www.av在线官网国产| 美女主播在线视频| 91精品国产国语对白视频| 黄色怎么调成土黄色| 麻豆精品久久久久久蜜桃| 国产成人午夜福利电影在线观看| 国产一区二区三区av在线| 黑人欧美特级aaaaaa片| 婷婷成人精品国产| 欧美最新免费一区二区三区| 亚洲色图 男人天堂 中文字幕| 欧美久久黑人一区二区| 99热全是精品| 19禁男女啪啪无遮挡网站| 亚洲一卡2卡3卡4卡5卡精品中文| 国产视频首页在线观看| 亚洲国产欧美日韩在线播放| 欧美最新免费一区二区三区| 一边亲一边摸免费视频| 午夜激情av网站| 国产午夜精品一二区理论片| 欧美人与性动交α欧美精品济南到| 久久青草综合色| 国产精品蜜桃在线观看| 亚洲av日韩精品久久久久久密 | 一本—道久久a久久精品蜜桃钙片| 一级毛片我不卡| 在线观看人妻少妇| 这个男人来自地球电影免费观看 | 五月开心婷婷网| 99热国产这里只有精品6| 中文字幕高清在线视频| 亚洲国产精品国产精品| 欧美在线一区亚洲| 国产精品女同一区二区软件| 韩国精品一区二区三区| av网站免费在线观看视频| 国产亚洲午夜精品一区二区久久| 免费黄色在线免费观看| 国产一卡二卡三卡精品 | 国产 精品1| 国产av一区二区精品久久| 午夜日本视频在线| 免费观看性生交大片5| 久久人人97超碰香蕉20202| 老司机影院毛片| 色吧在线观看| 丝袜脚勾引网站| 久久久欧美国产精品| 欧美精品一区二区免费开放| av国产久精品久网站免费入址| 国产亚洲精品第一综合不卡| 久久天躁狠狠躁夜夜2o2o | 亚洲欧美日韩另类电影网站| 在线观看人妻少妇| 老汉色av国产亚洲站长工具| 最近中文字幕2019免费版| 18在线观看网站| 亚洲美女黄色视频免费看| 日韩一卡2卡3卡4卡2021年| 免费久久久久久久精品成人欧美视频| 欧美日韩视频高清一区二区三区二| 久久青草综合色| 久久精品亚洲熟妇少妇任你| 麻豆精品久久久久久蜜桃| tube8黄色片| 亚洲人成网站在线观看播放| 国产精品av久久久久免费| 国产精品 国内视频| 最新在线观看一区二区三区 | 亚洲av综合色区一区| 黄色一级大片看看| 啦啦啦在线观看免费高清www| 超碰成人久久| 丝瓜视频免费看黄片| 成人午夜精彩视频在线观看| 国产成人精品在线电影| 中文天堂在线官网| 波多野结衣一区麻豆| 精品久久蜜臀av无| 天堂8中文在线网| 午夜激情av网站| 天天影视国产精品| 欧美激情高清一区二区三区 | 亚洲国产成人一精品久久久| 80岁老熟妇乱子伦牲交| 欧美最新免费一区二区三区| 一区二区三区精品91| 精品久久蜜臀av无| 色播在线永久视频| 韩国高清视频一区二区三区| 久久狼人影院| 久久女婷五月综合色啪小说| 91国产中文字幕| 久久久久国产一级毛片高清牌| 久久青草综合色| 色婷婷久久久亚洲欧美| 嫩草影视91久久| 亚洲男人天堂网一区| 午夜日本视频在线| 国产视频首页在线观看| 国产精品久久久久久精品古装| 精品人妻熟女毛片av久久网站| 亚洲一区二区三区欧美精品| av电影中文网址| 久久久精品免费免费高清| 亚洲美女黄色视频免费看| 午夜91福利影院| 久久精品熟女亚洲av麻豆精品| 街头女战士在线观看网站| 午夜91福利影院| 久久精品熟女亚洲av麻豆精品| 91aial.com中文字幕在线观看| av国产久精品久网站免费入址| 男女无遮挡免费网站观看| 在线观看免费日韩欧美大片| 一本久久精品| 深夜精品福利| 菩萨蛮人人尽说江南好唐韦庄| 国产精品熟女久久久久浪| 亚洲成人国产一区在线观看 | 国产免费视频播放在线视频| 秋霞伦理黄片| 18在线观看网站| 少妇猛男粗大的猛烈进出视频| 在线观看人妻少妇| 成人手机av| 看免费av毛片| 成年动漫av网址| 哪个播放器可以免费观看大片| 亚洲国产最新在线播放| 无遮挡黄片免费观看| 亚洲一码二码三码区别大吗| 少妇猛男粗大的猛烈进出视频| 精品国产一区二区三区四区第35| 亚洲一卡2卡3卡4卡5卡精品中文| 免费在线观看视频国产中文字幕亚洲 | 免费观看a级毛片全部| av在线播放精品| 国产一区有黄有色的免费视频| 精品免费久久久久久久清纯 | 波多野结衣一区麻豆| 搡老乐熟女国产| 久久久久久免费高清国产稀缺| 99re6热这里在线精品视频| 亚洲精品视频女| 99久久精品国产亚洲精品| 精品少妇久久久久久888优播| 一级a爱视频在线免费观看| 精品亚洲乱码少妇综合久久| 午夜免费男女啪啪视频观看| 久久免费观看电影| 9色porny在线观看| 久热爱精品视频在线9| 91成人精品电影| 老司机影院毛片| 欧美日韩视频精品一区| 精品国产一区二区三区久久久樱花| 18在线观看网站| 国产成人啪精品午夜网站| 天天添夜夜摸| 精品午夜福利在线看| 热99国产精品久久久久久7| 乱人伦中国视频| 久久国产精品大桥未久av| 日韩制服骚丝袜av| 男女国产视频网站| 老汉色∧v一级毛片| 19禁男女啪啪无遮挡网站| 日韩伦理黄色片| 国产男人的电影天堂91| 欧美日韩av久久| 国产色婷婷99| 美女大奶头黄色视频| 伦理电影免费视频| 青春草国产在线视频| 欧美黑人精品巨大| videosex国产| e午夜精品久久久久久久| 亚洲精品国产av成人精品| 国产亚洲精品第一综合不卡| 十八禁网站网址无遮挡| 中文字幕人妻熟女乱码| 最近中文字幕高清免费大全6| 国产亚洲一区二区精品| 99国产精品免费福利视频| 欧美日韩视频精品一区| 综合色丁香网| 男人舔女人的私密视频| 黑丝袜美女国产一区| xxx大片免费视频| 国产无遮挡羞羞视频在线观看| 亚洲久久久国产精品| 中文欧美无线码| 亚洲,一卡二卡三卡| 亚洲av成人不卡在线观看播放网 | 亚洲情色 制服丝袜| 久久久久久免费高清国产稀缺| 欧美黑人欧美精品刺激| 国产精品 国内视频| 久久热在线av| 国产成人欧美| videosex国产| 国产成人欧美在线观看 | 国产日韩一区二区三区精品不卡| 丰满饥渴人妻一区二区三| 精品人妻熟女毛片av久久网站| 成人国产麻豆网| 美国免费a级毛片| 精品一区二区三卡| 午夜日本视频在线| 免费观看性生交大片5| 亚洲少妇的诱惑av| 国产成人精品久久久久久| 色综合欧美亚洲国产小说| 一二三四在线观看免费中文在| 男女床上黄色一级片免费看| 美女主播在线视频| 久久精品国产综合久久久| videos熟女内射| 国产av精品麻豆| xxx大片免费视频| 麻豆乱淫一区二区| 日本黄色日本黄色录像| 中文天堂在线官网| 日韩av免费高清视频| 亚洲欧洲精品一区二区精品久久久 | 最近手机中文字幕大全| 日韩电影二区| 美女大奶头黄色视频| 亚洲精品av麻豆狂野| 午夜福利一区二区在线看| 香蕉国产在线看| 久久精品亚洲熟妇少妇任你| 亚洲欧美成人精品一区二区| 日本一区二区免费在线视频| 美国免费a级毛片| 日韩欧美一区视频在线观看| 日本av免费视频播放| 一级毛片我不卡| 考比视频在线观看| 欧美日韩一级在线毛片| 老司机深夜福利视频在线观看 | 伦理电影免费视频| 久久久久久久国产电影| 大话2 男鬼变身卡| 人人妻人人添人人爽欧美一区卜| 自线自在国产av| 欧美日韩综合久久久久久| 女人精品久久久久毛片| 777久久人妻少妇嫩草av网站| 亚洲欧美成人精品一区二区| 午夜老司机福利片| 嫩草影院入口| 男女无遮挡免费网站观看| 成人手机av| 99re6热这里在线精品视频| 亚洲av成人精品一二三区| 99久国产av精品国产电影| 国产伦理片在线播放av一区| 国产一区二区在线观看av| a级毛片黄视频| 九草在线视频观看| 狂野欧美激情性xxxx| 国产乱来视频区| 亚洲av电影在线进入| 一边亲一边摸免费视频| 天天影视国产精品| 色吧在线观看| 午夜影院在线不卡| 亚洲精品乱久久久久久| 天天影视国产精品| 国产亚洲欧美精品永久| 秋霞伦理黄片| 国产片内射在线| h视频一区二区三区| 在线观看三级黄色| 久久精品熟女亚洲av麻豆精品| 国产精品人妻久久久影院| 久久精品国产a三级三级三级| 99热国产这里只有精品6| 美女视频免费永久观看网站| 男女免费视频国产| 人人澡人人妻人| 亚洲精品国产区一区二| 国产成人一区二区在线| 又大又黄又爽视频免费| 无限看片的www在线观看| 80岁老熟妇乱子伦牲交| 人人妻人人澡人人看| 不卡av一区二区三区| 尾随美女入室| 最近最新中文字幕免费大全7| 亚洲欧美精品综合一区二区三区| 伦理电影大哥的女人| 午夜久久久在线观看| 国产爽快片一区二区三区| 国产成人精品无人区| 精品少妇久久久久久888优播| 免费少妇av软件| 哪个播放器可以免费观看大片| 国产片特级美女逼逼视频| 在线天堂中文资源库| 中文精品一卡2卡3卡4更新| 亚洲精品国产av蜜桃| 18在线观看网站| 无限看片的www在线观看| 黄色视频不卡| 日韩中文字幕视频在线看片| 国产日韩欧美在线精品| 亚洲欧洲日产国产| 熟女av电影| 亚洲情色 制服丝袜| 欧美黑人欧美精品刺激| av在线播放精品| 欧美激情极品国产一区二区三区| 亚洲婷婷狠狠爱综合网| 黑丝袜美女国产一区| 丰满少妇做爰视频| 国产免费福利视频在线观看| 日韩 亚洲 欧美在线| 欧美精品人与动牲交sv欧美| 久热爱精品视频在线9| 日韩大码丰满熟妇| 国产成人欧美| 日韩制服骚丝袜av| 搡老岳熟女国产| 亚洲综合色网址| 国产xxxxx性猛交| 免费久久久久久久精品成人欧美视频| 赤兔流量卡办理| 在线观看国产h片| 宅男免费午夜| 久久97久久精品| 久久久国产精品麻豆| 国产免费一区二区三区四区乱码| 国产av码专区亚洲av| 日韩免费高清中文字幕av| 国产免费福利视频在线观看| 一级a爱视频在线免费观看| 亚洲av国产av综合av卡| 美女视频免费永久观看网站| 日韩制服骚丝袜av| 天天躁狠狠躁夜夜躁狠狠躁| 多毛熟女@视频| 人妻 亚洲 视频| www.熟女人妻精品国产| 人妻一区二区av| 看免费av毛片| 国产av精品麻豆| 热99国产精品久久久久久7| 天天操日日干夜夜撸| 老司机在亚洲福利影院| 1024视频免费在线观看| 丝袜在线中文字幕| 性少妇av在线| 久久国产精品男人的天堂亚洲| 国产精品三级大全| 午夜福利,免费看| 啦啦啦中文免费视频观看日本| 女人久久www免费人成看片| 久久精品国产综合久久久| 国产伦人伦偷精品视频| a 毛片基地| 婷婷色麻豆天堂久久| 热re99久久精品国产66热6| 别揉我奶头~嗯~啊~动态视频 | 妹子高潮喷水视频| 国产欧美日韩综合在线一区二区| 高清在线视频一区二区三区| 欧美日韩亚洲国产一区二区在线观看 | 亚洲av在线观看美女高潮| 七月丁香在线播放| 男人添女人高潮全过程视频| 9色porny在线观看| 成人免费观看视频高清| 色婷婷久久久亚洲欧美| 大香蕉久久成人网| 国产一级毛片在线| 欧美亚洲 丝袜 人妻 在线| 国产片特级美女逼逼视频| 在线天堂最新版资源| 丰满迷人的少妇在线观看| 波多野结衣av一区二区av| 黄片无遮挡物在线观看| 黄色视频在线播放观看不卡| 人体艺术视频欧美日本| 免费观看性生交大片5| 亚洲精品一二三| 精品午夜福利在线看| 99久久人妻综合| 99精品久久久久人妻精品| 青春草国产在线视频| 亚洲精品aⅴ在线观看| 嫩草影院入口| 看免费成人av毛片| 两个人看的免费小视频| 欧美变态另类bdsm刘玥| 国产成人欧美在线观看 | 精品国产国语对白av| 女性生殖器流出的白浆| 日韩成人av中文字幕在线观看| 亚洲欧美日韩另类电影网站| 男女边摸边吃奶| 亚洲av综合色区一区| 精品久久久久久电影网| 午夜免费观看性视频| 天美传媒精品一区二区| 老汉色av国产亚洲站长工具| xxxhd国产人妻xxx| 成年人免费黄色播放视频| 91老司机精品| 久久亚洲国产成人精品v| 丰满乱子伦码专区| 精品视频人人做人人爽| 各种免费的搞黄视频| 精品亚洲乱码少妇综合久久| 操出白浆在线播放| 老汉色∧v一级毛片| 久久99精品国语久久久| 国产av一区二区精品久久| av网站在线播放免费| 搡老岳熟女国产| 中国三级夫妇交换| 极品少妇高潮喷水抽搐| 日韩一卡2卡3卡4卡2021年| 日韩制服丝袜自拍偷拍| 成人黄色视频免费在线看| 亚洲成人一二三区av| 欧美精品一区二区免费开放| 亚洲三区欧美一区| 日韩人妻精品一区2区三区| a级毛片黄视频| 丝袜人妻中文字幕| 久久精品国产a三级三级三级| 高清av免费在线| 精品人妻熟女毛片av久久网站| 女人爽到高潮嗷嗷叫在线视频| 色精品久久人妻99蜜桃| 久久久久久久国产电影| 美女扒开内裤让男人捅视频| 久久精品国产亚洲av涩爱| 亚洲欧美清纯卡通| 91国产中文字幕| 极品少妇高潮喷水抽搐| 中文字幕最新亚洲高清| 天天添夜夜摸| 国产精品免费视频内射| 精品国产一区二区久久| 欧美变态另类bdsm刘玥| 色播在线永久视频| 亚洲精品日韩在线中文字幕| 亚洲伊人色综图| 一边亲一边摸免费视频| 岛国毛片在线播放| 老司机在亚洲福利影院| 别揉我奶头~嗯~啊~动态视频 | 精品久久蜜臀av无| 丁香六月天网| 日本午夜av视频| 国产无遮挡羞羞视频在线观看| 欧美日韩视频精品一区| 悠悠久久av| 最黄视频免费看| 欧美成人精品欧美一级黄| 成人黄色视频免费在线看| 飞空精品影院首页| 久久精品久久久久久噜噜老黄| 三上悠亚av全集在线观看| 99香蕉大伊视频| 九九爱精品视频在线观看| bbb黄色大片| 高清在线视频一区二区三区| 成人国产av品久久久| 亚洲伊人色综图| 七月丁香在线播放| 久久久国产欧美日韩av| 日韩制服骚丝袜av| 91成人精品电影| 国产一区亚洲一区在线观看| 成人午夜精彩视频在线观看| 在线观看国产h片| 不卡视频在线观看欧美| 亚洲精品av麻豆狂野| 波野结衣二区三区在线| 人妻人人澡人人爽人人| 国产女主播在线喷水免费视频网站| 九色亚洲精品在线播放| 人体艺术视频欧美日本| 亚洲四区av| 国产精品 国内视频| 亚洲三区欧美一区| 一区在线观看完整版| 自线自在国产av| 国产成人免费观看mmmm| 亚洲第一av免费看| 国产精品免费大片| 考比视频在线观看| 国产成人av激情在线播放| 老汉色av国产亚洲站长工具| 亚洲精品av麻豆狂野| 亚洲av电影在线进入| 国产在视频线精品| 亚洲欧美一区二区三区黑人| 一二三四在线观看免费中文在| 中文欧美无线码| 国产爽快片一区二区三区| 成人国产av品久久久| 尾随美女入室| 在线观看免费高清a一片| 黄频高清免费视频| 久久久久国产精品人妻一区二区| 一区在线观看完整版| 国产日韩欧美亚洲二区| 亚洲国产中文字幕在线视频| 亚洲久久久国产精品| 一级毛片我不卡| 亚洲一区二区三区欧美精品| 久久久久久人人人人人| 国产精品秋霞免费鲁丝片| 精品一区二区三卡| 欧美日韩视频高清一区二区三区二| 成人亚洲欧美一区二区av| 欧美日韩精品网址| 99精品久久久久人妻精品| 欧美精品高潮呻吟av久久| 国产高清国产精品国产三级| 亚洲在久久综合| 老司机深夜福利视频在线观看 | 国产精品久久久人人做人人爽| xxxhd国产人妻xxx| 国产熟女欧美一区二区| www日本在线高清视频| 日韩av不卡免费在线播放| 另类精品久久| 亚洲伊人久久精品综合| 国产av一区二区精品久久| 最近中文字幕高清免费大全6| 色网站视频免费| 国产黄色视频一区二区在线观看| 在线观看免费日韩欧美大片| 国产在线一区二区三区精| www.精华液| 高清视频免费观看一区二区| 少妇猛男粗大的猛烈进出视频| 男女之事视频高清在线观看 | 久久精品久久精品一区二区三区| 欧美最新免费一区二区三区| 亚洲国产精品成人久久小说| 香蕉国产在线看| 新久久久久国产一级毛片| 黑人猛操日本美女一级片| 成年人免费黄色播放视频|