• <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 ?

    An injection-locking diode laser at 671 nm with a wide tuning range up to 6 GHz

    2023-10-11 07:55:34HongFangSong宋紅芳YueShen沈玥andKeLi李可
    Chinese Physics B 2023年9期
    關(guān)鍵詞:李可

    Hong-Fang Song(宋紅芳), Yue Shen(沈玥), and Ke Li(李可),?

    1School of Science,Huzhou University,Huzhou 313000,China

    2Strong-coupling Physics International Research Laboratory,Huzhou University,Huzhou 313000,China

    Keywords: injection lock,diode laser, 6Li atoms

    1.Introduction

    In recent decades, with the development of laser technology, cold-atom physics has become an active forefront research field.Due to their high maneuverability, cold atoms are used in quantum frequency standards,[1,2]quantum information,[3]and quantum precision measurement,[4,5]as well as in the construction of a model system to simulate exotic physical effects or physical systems.[6,7]

    Because of the broad Feshbach resonances, which can be utilized to control inter-atomic interactions precisely,6Li atoms are popular in quantum simulation and quantum manybody physics.[8,9]However,there are several challenges when preparing ultra-cold lithium gas: the high melting point of 180.5°C results in bulky experimental systems for an accompanied atomic furnace maintained at a high temperature above 300°C; and the closely spaced hyperfine structure of6Li leads to less effective sub-Doppler cooling.[10]In Zeeman slowing and laser cooling,[11–15]one needs to prepare narrow-linewidth (<1 MHz) 671 nm lasers to drive the|2S1/2〉→|2P3/2〉quantum transitions of6Li atoms.However,it is hard to find powerful and cost-effective laser sources at 671 nm.The commercially available laser light generated by the external-cavity diode laser(ECDL)has a narrow linewidth that is much less than 1 MHz, but suffers from low emission power (e.g.,<30 mW).The power can be amplified with a tapered amplifier(TA),but it is still less than 500 mW due to technical reasons.The alternative is based on frequency doubling of a 1342 nm laser that can generate high power up to 2.5 W,[15,16]but it costs more.The objective of this study is to search for an alternative method for the preparation of a highpower,cost-effective laser source at 671 nm.

    Injection locking refers to the process of injecting seeding light into the resonator of a slave laser, and forcing the slave laser to emit at the same optical frequency as the seeding light.This technique has very important applications in the construction of a single-frequency, high-power, low-noise and costeffective laser source.It was proposed by Adler in 1946.[17,18]Razavi explained this in terms of phase compensation.[19]Injection locking was first realized in a He–Ne laser by Steier and Stover,who directly injected a beam from a He–Ne laser into another one in 1966.[20]Kobayashi and Kimura effectively carried out injection locking in an AlGaAs doubleheterostructure laser in 1981,[21]which was the first time that injection locking was achieved in a semiconductor laser.Since then,a large number of injection locking procedures in semiconductor lasers have been realized.[21–25]Pagett and his colleagues carried out injection locking at 461 nm with an up to 10-mW seeding laser,[24]and the light was efficiently used in the laser cooling of a strontium Zeeman slower.

    Here,a compact diode laser module is reported,in which the slave laser can be injection locked with less than 2-mW seeding power and can generate 671 nm laser light up to 150 mW.The performance of the injection-locked laser is evaluated by measuring the beat frequency spectrum,power stability and beam quality(M2h=1.30,M2v=1.17).The injectionlocked laser has a wide tuning range up to 6 GHz.Two application examples using the developed injection-locked laser are demonstrated in detail, including resolving the groundstate hyperfine structures and successful Zeeman slowing of6Li atoms.We will further discuss its application in magnetooptic trapping and gray molasses cooling[26]experiments of6Li atoms.

    2.Design and experimental arrangement

    A schematic of the design and experimental arrangement for implementing and assessing the injection-locking diode laser is shown in Fig.1.The area enclosed by a dashed rectangle is the module which adopts the master–slave scheme,with all the elements integrated on a 20 cm by 30 cm aluminum breadboard.The integrated design makes the module portable and flexible for use in different scenarios.Emission of the slave laser is collimated with an aspherical lens(Thorlabs,C230TMD-A) and passes through a half-wave plate (HWP)and an optical isolator in series.The optical isolator is integrated with two polarization beam splitters(PBS),and has a high extinction ratio of about 30 dB.The light passing through the optical isolator is horizontally polarized.A maximized transmission up to 90% at 670 nm through the optical isolator is approached by finely adjusting the HWP.There is still weak light leaking from the reflection port.The PBS on the output port of the isolator is used to inject the seeding light.The seeding light is polarized vertically and directed into the reflection port of the PBS, and then it propagates against the emitting direction of the slave laser.A stable optical path for proper injection locking can be established by maximizing the fiber collection efficiency of the leaked light from the PBS reflection port.This method is based on the principle of optical path reversibility and ensures that the fiber input port on the module is ready for quick injection locking.

    The slave-laser diode (Mitsubishi, ML101J27) is traditionally used in portable high-density optical disc drives and rewritable DVD drives and runs in multi-longitudinal mode.It is installed inside a laser mount (Thorlabs, LDM56/M),which is controlled by both a temperature controller(Thorlabs,TED200C) and a current controller (Thorlabs, LDC205C).The temperature controller has excellent temperature stability of no more than 0.002°C,and the current controller has an accuracy of±0.5 mA.The seeding laser is derived from a master laser, which is a grating-stabilized external-cavity diode laser(TOPTICA,DL Pro 671)with a wavelength centered at 671 nm, a nominal output laser power of 30 mW and a typical linewidth~250 kHz (5 μs integration time).The available laser power measured after the 60 dB optical isolator is~25 mW.A small part of the master-laser emission(<2 mW)is collected into a polarization-maintaining single-mode fiber and guided to the injection-locking module.Figure 1 also shows the experimental arrangement for evaluating the performance of injection-locked lasers.In doing so,the slave laser is split into three parts after it passes straight through the optical isolator.They are used as the light sources for monitoring the longitudinal mode with a Fabry–Pérot cavity(FP cavity), observing the saturation absorption spectrum(SAS)of6Li atoms and frequency beating spectrum separately.Details of each measurement will be described in the following sections.

    Fig.1.A schematic of the design and experimental arrangement.The area on the left enclosed by a dashed rectangle is the injection-locking module.PMSF:polarization maintaining single-mode optical fiber,λ/2:half-wave plate,PBS:polarization beam splitter,AOM:acousto–optic modulator,BS:beam splitter,FP cavity: Fabry–Pérot cavity,Li cell: lithium cell,λ/4: quarter-wave plate.

    3.Approaching injection locking

    To achieve injection locking, the wavelength difference between the master laser and the slave laser needs to be small enough.The slave laser emits laser light with a center wavelength of~660 nm at 25°C,while the emission wavelength of the master laser is centered at~671 nm.The ability to shift the center wavelength of the slave laser up by nearly 10 nm is critical for successful injection locking.We manage to achieve this goal via two-stage wavelength tuning, which is based on the principle that the center wavelength of a laser diode has strong correlations with the temperature and laser current.First, the diode temperature is maintained at 20°C, and the center wavelength is tuned up~3.5 nm(Fig.2(a),black dots)by varying the laser current from 150 mA to 350 mA.Then,it is shifted~6 nm further toward the long wavelength direction by heating the laser diode to a high temperature above 70°C.As shown in Fig.2(a),the free-running slave-laser diode has a center wavelength~670 nm when the temperature and laser current are maintained at 75°C and 300 mA,respectively.

    A more detailed measurement for searching for suitable operating conditions to bring the center wavelength of the slave laser to that of the master laser is shown in Fig.2(a).The wavelength of the slave-laser diode is monitored using a wavemeter (High Finesse, WS6-200).Although the freerunning laser diode emits light in multi-longitudinal mode,the wavemeter shows stable reading at discrete temperature and laser current positions.The points plotted in Fig.2(a)are discrete and nearly follow the same trend for all temperatures with a response parameter~0.0175 nm/mA.It has been verified that once the diodes emit at a wavelength greater than 668 nm they can be successfully injection locked.The dashed line in black in Fig.2(a) marks the wavelength of 668 nm.Upon considering that the performance of electronics inside the laser mount could be worsening,we did not heat the slave laser to temperatures higher than 80°C.

    The slave-laser diode operating at a high temperature has a greater threshold current and a reduced maximum output power.Figure 2(b)shows the results of threshold current measurements at different temperatures.The threshold current of the slave-laser diode is 83 mA at 20°C.It increases to 119 mA,124 mA and 132 mA when the temperature is stabilized at 70°C, 75°C and 80°C, respectively.The emission power increases almost linearly with the current above the threshold,and has an approximate slope efficiency~0.80 W/A at 20°C.At high temperature, ranging from 70°C to 80°C, the slope efficiency shows apparent deviation from the linear approximation and drops to below 0.50 W/A in the current range between 300 mA and 350 mA.The slave laser can still generate 120.3-mW emission power at 80°C when the driving current is set at 345 mA.A quick measurement on nine pieces of the same type of laser diodes shows that they can generate an averaged emission power of about 148.7 mW at 350 mA and 70°C.Their standard power deviation is smaller than 12%.Also, the emission wavelength of each laser diode can be effectively tuned above 668 nm by using the method described above.Therefore, it can be concluded that the data shown in Fig.2 can serve as a reliable reference for the special application using this type of laser diode for injection locking.

    Fig.2.Measurements on the center wavelength and threshold current of the free-running slave-laser diode.(a) Each point refers to a stable wavelength reading on the wavemeter.They are discrete but nearly follow the same trend for all temperatures.(b)The lasing threshold current is ~80 mA at 20 °C,and it shifts to ~130 mA at 80 °C.

    The successful injection-locking signal was monitored using the transmission spectrum from a Fabry–Pérot interferometer(Thorlabs,SA200-5B),which has a 1.5-GHz free spectral range and 7.5-MHz resolution.The cavity length of the interferometer was scanned with an external saw-tooth voltage signal produced by a function generator.The black curve in Fig.3(a) refers to the transmission spectrum of the freerunning state, where the peaks appear in a chaotic pattern.In contrast,the red curve refers to the injection-locking state,which features two narrow transmission peaks with all other side modes diminished completely.After the temperature of the laser diode was maintained above 70°C, we carefully scanned the current of the diode to seek successful locking.Once the locking is achieved,the FP cavity signal turns from a black line to a red line,as shown in Fig.3(a).Based on this method,we have checked each point shown in Fig.2(a)to determine if successful injection locking can be approached.We found that once the stable reading of the wavemeter is above 668 nm,successful injection locking is always achievable.

    Fig.3.(a)The transmission spectrum of the slave laser measured using a Fabry–Pérot interferometer.The black and red curves refer to the freerunning state and the injection-locking state, respectively.(b) Lock-in current points at different injection powers searched at 75 °C.Each point represents a stable injection-locking state within a narrow current zone(<1.5 mA).The scattered lock-in points span wider ranges at higher injection powers.Dots of the same shape and color lined up in the vertical direction belong to the same lock-in current zone.

    The stable injection-locking state occurs in narrow current zones(<1.5 mA).We have tried to search all the current points that can be firmly locked when the laser temperature was stabilized at 75°C.As shown in Fig.3(b), points lined up in the horizontal direction are searched at a fixed injection power,which spans in a wider range if the injection laser power is fixed at a higher level.According to the measurements shown in Figs.2(b)and 3(b),the injection-locked module working at 75°C that can generate emission power higher than 100 mW has relatively small requirements regarding the laser current(>300 mA)and injection power(>0.5 mW).

    For comparison, we did the same search on the lock-in current zones with the temperature set at 70°C and 80°C,separately.When the seeding power is as high as 1.9 mW,the minimum lock-in current points at 70°C, 75°C and 80°C are 287.52 mA, 196.92 mA and 151.46 mA, respectively.It should be noted that the slave-laser diode could be damaged by high injection power.Based on our experiment,it is always safe for the module to work with an injection power below 2 mW.We have checked the center wavelength of the freerunning slave laser, which has the same current and temperature settings as those where the module can be successfully injection locked.They range from 668 nm to 672 nm, which means that the largest distance that the slave-laser wavelength can be pulled by the seeding light should be about 3 nm.

    4.Measurements and application

    The slave laser’s good performance has been verified via measurement of the beam quality, power stability and frequency components.The beam-quality factor (M2factor) is measured using a completeM2measurement system (Thorlabs, M2MS-BC106N).A small part of the slave laser power is directed into the instrument after the isolator, which is not mentioned in Fig.1.TheM2factor measurement is based on a 250-mm focal length lens, which is placed in front of the entrance of the instrument.TheM2system can automatically capture a series of beam profiles at different axial positions.Figure 4(a) shows the measuredD4σdiameters at each position, and theM2factors in the vertical and horizontal directions are 1.17 and 1.30, respectively.This means that the slave-laser emission is elliptical but close to single transverse mode.An anamorphic prism pair may be used to circularize the beam shape.But the prism pair has low transmission(~80%)and worsens theM2factors;therefore,we abandoned it.In our further experimental application, the elliptical laser beam can be collected into a PMSF fiber with high collect efficiency up to 70%.

    Fig.4.(a)Fitting to obtain the M2 factors according to the D4σ diameter of the beam.The M2 factors in the vertical and horizontal directions are 1.17 and 1.30,respectively.The inset shows the mode profile of the beam.(b)The laser power varies within 1‰for two hours.The inset gives the variation in 5 minutes.(c)The laser current and emission power recorded over a long time around 400 daily operations.In the daily operation,the emission power is maintained at 140 mW by adjusting the driving current.

    Moreover,the power stabilities of the slave laser are also important for daily experimental application.As shown in Fig.4(b), the typical short-term power variation is no more than 1‰.To maintain a 140-mW output power, daily adjustment on the laser current is required, which was recorded for~13 months.As shown in Fig.4(c), we noticed that, except for increasing the laser current by~10 mA after 6-months of running,no further adjustment was required.This may indicate that the laser diode is decaying, but still has a lifetime of more than one year when working at a high temperature of about 70°C.

    To obtain the frequency component information of the slave laser,we have observed the beat frequency spectrum between the slave laser and the master laser.As shown in Fig.1,the slave-laser frequency was shifted down by 110 MHz with an AOM, and then combined with the master laser through a 50:50 beam splitter.To generate the optimum beating signal,their polarizations were carefully adjusted to be in the horizontal plane.The beat signal was detected by a photodiode(Thorlabs,PDA10A2)with 150-MHz bandwidth,and then analyzed by a spectrum analyzer(Keysight,N9010B)with a resolution bandwidth of 100 Hz and span of 100 kHz,as shown in Fig.5.The beat signal is centered at 110 MHz and has a full width at half maximum (FWHM) less than 2 kHz, which is only limited by the resolution of the spectrum analyzer.In this measurement, the results for the injection power of both 0.5 mW and 1.0 mW are quite close, which indicates that significant phase correlation between the slave laser and master laser can be reached at an injection power as low as 0.5 mW.[17]It also denotes that the injection-locked laser is running in purely single-longitudinal mode,with all the other frequency components cleared away within the 150 MHz detection bandwidth.

    Fig.5.The beat frequency spectrum between the slave-laser frequency shifted by an AOM centered at 110 MHz and the master laser at a diode temperature of 70 °C.The slave laser was injected with powers of both 0.5 mW and 1.0 mW.The resolution bandwidth is 100 Hz and the FWHM of the peak is less than 2 kHz.

    To further verify the linewidth of the slave laser, we use it as the light source for a standard SAS spectrum experiment of6Li atoms.The slave laser is locked with a 1.9-mW seeding laser at 80°C.The optical layout is shown in Fig.1, where the 220-μW probe light is divided from the slave laser.It can drive the 22S1/2–22P3/2transitions of6Li atoms, which are the so-called D2 line transitions,and has a natural linewidth of 2π×5.87 MHz.In this experiment,the master laser is scanned across~6 GHz at 1 Hz.As shown in Fig.6(a), the wide trough is the Doppler-broadened absorption profile related to the D2 line transition of6Li atoms,and the SAS signal of the7Li atoms can be clearly seen on the right wing of the profile.Each SAS peak can be fully resolved when the scanning range is narrowed down to 400 MHz,as shown in the inset of Fig.6(a).The SAS signal has a noise floor of 0.12 mVpp,and a signal amplitude of 59.0 mVpp, resulting in a high signalto-noise ratio of 492.The frequency separation between the two upwards SAS peaks is~228 MHz, which is related to the hyperfine splitting of the 2S1/2ground state of6Li atoms.The three SAS peaks are fitted with a Lorentz profile,yielding FWHM widths of 10.84 MHz, 11.40 MHz and 16.10 MHz,respectively.The wider SAS widths compared to the natural linewidth may be attributed to power broadening.[27]

    Fig.6.(a) The saturation absorption spectrum recorded using the slave laser that is injection locked to the master laser.The lithium cell is heated to 310 °C,and the light is 200 μW in power and 0.5 mm in beam waist.(b) The MOT loading process, with the slave laser as Zeeman cooling light.Time zero is assigned as the time when the MOT starts to work.

    Figure 6(b)demonstrates the accumulation signal of cold6Li atoms in the MOT.The slow atoms that can be captured by the MOT are supplied by a Zeeman slower, in which6Li atoms are slowed down by near-resonant light produced by the injection-locked slave laser.In the experiment, the master laser is locked onto the 22S1/2,F=3/2→22P3/2resonant transition of6Li atoms.The frequency of slowing light is down shifted by 100 MHz with an AOM; therefore, it is red-detuned from the resonance.The first order diffraction efficiency of the AOM is~77%, and the diffracted light is then collected into a PMSF fiber at a collection efficiency of~70%.Finally, the maximum available laser power that can be used as slowing light is~60.0 mW.In the Zeeman-slowing and MOT loading experiment, the number of6Li atoms increases in the MOT rapidly, and saturates at 12.5×108after 50 seconds.

    Compared to the TA chip,which requires a seeding laser power~20 mW,the module reported in our work requires an injection power of no more than 2 mW.By considering that the master laser can provide up to 20 mW of laser power,we can estimate that one master laser can provide seeding light for up to 10 modules.To build a complete cold-atom system working with6Li atoms, three types of laser beams with different frequencies need to be prepared.One of them is for Zeeman slowing,which is described above.The other two are for MOT operation,and they are called the MOT-cooling beam and the MOT-repump beam.[28]Fortunately,the frequency differences between them are from 100 MHz to 300 MHz and fall suitably within the typical frequency modulation range of an AOM.This gives us a special advantage in constructing a6Li cold-atom system for the laser system can be accomplished by building three injection-locking modules with frequency-shifted seeding laser beams derived from a single master laser.It is also applicable to build two more identical injection-locking modules as the laser source for gray molasses cooling of6Li atoms,[26]which is a special laser cooling experiment that is used to prepare a cold6Li cloud to a temperature well below the Doppler cooling limit.[10,29]Moreover,the slave laser has a narrow linewidth that is comparable to the master laser;it can be used as a light source for absorption detection.For an existing laboratory, it is also a good choice to prepare two such modules to prevent experimental interruption caused by laser maintenance or repairs,which could take several months.

    5.Conclusion

    We have developed a compact injection-locking module,which can be used as a 671-nm laser source to supply high power and narrow-linewidth emission for laser cooling and trapping of6Li atoms.We can conclude that injection locking is a technique that combines the narrow linewidth of the seeding light with the high power of the slave laser.The first step is to inject enough seeding-light power into the slavelaser diode against its emitting direction.The frequency difference between the seeding and slave lasers needs to be tuned as small as possible, which can be realized by increasing the temperature and working current of the slave diode.In our research,once the frequency difference is within 3 nm,no more than 1.9-mW injection power is sufficient to achieve successful locking.It can be inferred that if the frequency difference increases,greater injection power may be needed,and a small frequency difference with big injection power can lead to more robust locking.The slave laser can be scanned in a wide range of 6 GHz in the most robust locking situation.The injectionlocking module has been used as a Zeeman slowing beam as a part of our6Li MOT system,which can collect over 109atoms within 50 s.Although the laser diode works at a high temperature above 70°C,the module can operate for at least one year with almost no weakening in performance.Since every component is commercially available and the module has a compact design,it has the unique advantage of fast construction at low cost and can easily serve different experimental purposes,such as the saturation absorption spectrum, Zeeman slowing,MOT beams and gray molasses.

    Acknowledgements

    Project supported by the National Natural Science Foundation of China (Grant Nos.12035006, 12205095, and 12147219) and the Natural Science Foundation of Zhejiang Province(Grant No.LQ21A040001).

    猜你喜歡
    李可
    幸福就是有人管有人問
    “媽系老婆”讓我明白:幸福就是有人管
    幸福(2023年20期)2023-10-22 17:41:26
    幸福就是有人管有人問
    “媽系老婆”讓我明白:幸福就是有人管
    婦女(2023年5期)2023-06-11 07:28:17
    Efficient implementation of x-ray ghost imaging based on a modified compressive sensing algorithm
    科技活動周主會場掠影
    科技活動周主會場掠影
    李可從中氣論治消化道腫瘤
    請學(xué)霸伴讀釀悲劇,倆孩子的悲催人生誰來埋單?
    宮保雞丁
    小說月刊(2017年6期)2017-06-14 18:26:37
    国产精品人妻久久久影院| 亚洲欧美激情在线| 69精品国产乱码久久久| 久久久精品免费免费高清| 欧美日韩精品网址| 日韩免费高清中文字幕av| 久久久亚洲精品成人影院| 美女国产高潮福利片在线看| 满18在线观看网站| 久久久久精品性色| 天天躁夜夜躁狠狠久久av| 日韩 亚洲 欧美在线| 男女之事视频高清在线观看 | 精品国产国语对白av| 国产av国产精品国产| 9色porny在线观看| 视频区图区小说| 国产熟女欧美一区二区| 精品国产一区二区三区四区第35| 亚洲五月色婷婷综合| 亚洲欧美精品综合一区二区三区| 日本色播在线视频| 老熟女久久久| 久久久久视频综合| 精品人妻在线不人妻| 国产视频首页在线观看| 国产毛片在线视频| 免费观看性生交大片5| 成人亚洲精品一区在线观看| 99九九在线精品视频| 免费女性裸体啪啪无遮挡网站| 国产老妇伦熟女老妇高清| 色精品久久人妻99蜜桃| 一边摸一边做爽爽视频免费| 如日韩欧美国产精品一区二区三区| 婷婷色av中文字幕| 69精品国产乱码久久久| 高清在线视频一区二区三区| 黄色 视频免费看| 两性夫妻黄色片| 亚洲国产成人一精品久久久| 少妇被粗大猛烈的视频| 久久精品国产a三级三级三级| e午夜精品久久久久久久| 欧美97在线视频| 久久久精品94久久精品| 欧美黄色片欧美黄色片| 啦啦啦在线免费观看视频4| 中文字幕另类日韩欧美亚洲嫩草| 女性被躁到高潮视频| 一级,二级,三级黄色视频| 免费看av在线观看网站| 人人妻人人澡人人看| 国产亚洲av片在线观看秒播厂| 在线观看三级黄色| 亚洲国产看品久久| 久久午夜综合久久蜜桃| 大香蕉久久网| 超碰成人久久| 亚洲精品自拍成人| 秋霞在线观看毛片| 国产欧美日韩综合在线一区二区| 国产野战对白在线观看| 自拍欧美九色日韩亚洲蝌蚪91| 人人妻人人爽人人添夜夜欢视频| 好男人视频免费观看在线| 亚洲七黄色美女视频| 啦啦啦啦在线视频资源| 日本午夜av视频| 人人妻,人人澡人人爽秒播 | 国产不卡av网站在线观看| 高清不卡的av网站| 精品酒店卫生间| 一级毛片我不卡| 欧美日韩亚洲综合一区二区三区_| 亚洲成国产人片在线观看| 久久人人97超碰香蕉20202| 七月丁香在线播放| av视频免费观看在线观看| 午夜免费鲁丝| 香蕉丝袜av| 亚洲av综合色区一区| 国产精品人妻久久久影院| 国产毛片在线视频| 中文字幕精品免费在线观看视频| 国产极品天堂在线| www.自偷自拍.com| 777米奇影视久久| 不卡视频在线观看欧美| 中文字幕精品免费在线观看视频| 中文欧美无线码| 丝袜喷水一区| 亚洲av电影在线观看一区二区三区| 国产又色又爽无遮挡免| 精品卡一卡二卡四卡免费| 汤姆久久久久久久影院中文字幕| 国产精品一国产av| 91aial.com中文字幕在线观看| 亚洲av日韩在线播放| 亚洲精品美女久久久久99蜜臀 | 亚洲欧美色中文字幕在线| 亚洲色图综合在线观看| 日韩av在线免费看完整版不卡| 涩涩av久久男人的天堂| 久久久久久久精品精品| 亚洲七黄色美女视频| 亚洲伊人色综图| 亚洲精品国产色婷婷电影| 90打野战视频偷拍视频| 久久久久久免费高清国产稀缺| 亚洲一级一片aⅴ在线观看| 亚洲伊人久久精品综合| 国产成人精品无人区| 国产成人精品福利久久| 午夜免费男女啪啪视频观看| 极品少妇高潮喷水抽搐| 999久久久国产精品视频| 亚洲国产精品成人久久小说| 99精品久久久久人妻精品| 亚洲精品一二三| 久久精品亚洲熟妇少妇任你| 亚洲美女视频黄频| 国产一卡二卡三卡精品 | 婷婷色av中文字幕| 国产人伦9x9x在线观看| 天天操日日干夜夜撸| 亚洲精品一区蜜桃| 中文字幕av电影在线播放| 18在线观看网站| 两个人免费观看高清视频| 午夜福利影视在线免费观看| 少妇被粗大猛烈的视频| 亚洲在久久综合| 天天躁日日躁夜夜躁夜夜| 美女主播在线视频| 亚洲视频免费观看视频| 欧美日韩av久久| 午夜激情久久久久久久| 五月开心婷婷网| 少妇人妻精品综合一区二区| 中文字幕色久视频| 欧美最新免费一区二区三区| 久久久久久人人人人人| 青青草视频在线视频观看| 亚洲国产欧美一区二区综合| 国产亚洲av片在线观看秒播厂| 9191精品国产免费久久| 国产精品秋霞免费鲁丝片| 久久av网站| 国产亚洲一区二区精品| www.精华液| 亚洲精品aⅴ在线观看| 欧美97在线视频| 老司机影院成人| 最新在线观看一区二区三区 | 午夜91福利影院| 在线观看免费午夜福利视频| 一本一本久久a久久精品综合妖精| 国产乱来视频区| av一本久久久久| 又大又爽又粗| 亚洲人成网站在线观看播放| 最近2019中文字幕mv第一页| 各种免费的搞黄视频| 精品国产乱码久久久久久男人| 老司机靠b影院| 校园人妻丝袜中文字幕| 日韩av不卡免费在线播放| 国产色婷婷99| 欧美精品亚洲一区二区| 一级毛片我不卡| 精品一区二区三区四区五区乱码 | 最近最新中文字幕大全免费视频 | 国产免费又黄又爽又色| 亚洲精品国产av成人精品| 国产精品亚洲av一区麻豆 | 搡老乐熟女国产| 亚洲精品久久久久久婷婷小说| 尾随美女入室| 老汉色∧v一级毛片| 国产免费视频播放在线视频| 99热国产这里只有精品6| 丝袜美腿诱惑在线| 免费看不卡的av| 亚洲精品在线美女| 国精品久久久久久国模美| 看非洲黑人一级黄片| 女性生殖器流出的白浆| 十八禁高潮呻吟视频| 最近手机中文字幕大全| 成年女人毛片免费观看观看9 | 美女高潮到喷水免费观看| 久久人人97超碰香蕉20202| 国语对白做爰xxxⅹ性视频网站| 大码成人一级视频| 国产精品久久久久久人妻精品电影 | 国产黄色免费在线视频| 婷婷色麻豆天堂久久| 麻豆av在线久日| 18在线观看网站| 性少妇av在线| a级毛片在线看网站| 九草在线视频观看| 免费黄频网站在线观看国产| 777久久人妻少妇嫩草av网站| 成人18禁高潮啪啪吃奶动态图| 免费观看a级毛片全部| 亚洲成人av在线免费| 成人午夜精彩视频在线观看| 丰满饥渴人妻一区二区三| 精品少妇内射三级| 美女扒开内裤让男人捅视频| 男女边吃奶边做爰视频| 最近手机中文字幕大全| 国产精品久久久久久精品电影小说| 亚洲精品第二区| 亚洲成人一二三区av| 亚洲专区中文字幕在线 | 成人手机av| 国产黄频视频在线观看| 99国产综合亚洲精品| 亚洲人成网站在线观看播放| 黑人巨大精品欧美一区二区蜜桃| 五月天丁香电影| 人人澡人人妻人| 免费不卡黄色视频| 一级,二级,三级黄色视频| 成人免费观看视频高清| 成年动漫av网址| 纯流量卡能插随身wifi吗| 老司机深夜福利视频在线观看 | 免费看av在线观看网站| 国产在视频线精品| 国产日韩一区二区三区精品不卡| 国产国语露脸激情在线看| 在线看a的网站| 99re6热这里在线精品视频| videos熟女内射| 欧美成人午夜精品| av国产久精品久网站免费入址| 日本猛色少妇xxxxx猛交久久| 精品国产乱码久久久久久小说| 成人毛片60女人毛片免费| 老汉色av国产亚洲站长工具| 亚洲国产毛片av蜜桃av| 亚洲精品在线美女| 色婷婷久久久亚洲欧美| 观看美女的网站| 一级片'在线观看视频| 亚洲天堂av无毛| 制服丝袜香蕉在线| 99re6热这里在线精品视频| 美女午夜性视频免费| 飞空精品影院首页| 下体分泌物呈黄色| 国精品久久久久久国模美| 男女边吃奶边做爰视频| 国产成人91sexporn| 国产极品天堂在线| 狠狠婷婷综合久久久久久88av| 捣出白浆h1v1| 考比视频在线观看| 国产乱人偷精品视频| 麻豆精品久久久久久蜜桃| av不卡在线播放| 嫩草影院入口| 丰满迷人的少妇在线观看| 最新在线观看一区二区三区 | 欧美成人精品欧美一级黄| 久久精品亚洲熟妇少妇任你| 91精品伊人久久大香线蕉| 国产亚洲最大av| 自拍欧美九色日韩亚洲蝌蚪91| 日韩不卡一区二区三区视频在线| 亚洲激情五月婷婷啪啪| 欧美日韩一区二区视频在线观看视频在线| 午夜福利,免费看| 成人午夜精彩视频在线观看| av在线老鸭窝| 亚洲欧美激情在线| av女优亚洲男人天堂| 精品久久久精品久久久| 亚洲国产精品一区三区| 日本猛色少妇xxxxx猛交久久| 亚洲一级一片aⅴ在线观看| 日韩伦理黄色片| 91aial.com中文字幕在线观看| 天天躁夜夜躁狠狠久久av| 黄频高清免费视频| 欧美日本中文国产一区发布| 美女午夜性视频免费| 一个人免费看片子| 日日啪夜夜爽| 久久人人97超碰香蕉20202| 蜜桃国产av成人99| 青春草国产在线视频| 狂野欧美激情性bbbbbb| 国产精品嫩草影院av在线观看| 精品少妇内射三级| 日日摸夜夜添夜夜爱| 黑人欧美特级aaaaaa片| 搡老乐熟女国产| av一本久久久久| 免费av中文字幕在线| 成人三级做爰电影| 在线观看三级黄色| av又黄又爽大尺度在线免费看| 十分钟在线观看高清视频www| 菩萨蛮人人尽说江南好唐韦庄| 哪个播放器可以免费观看大片| 在线天堂最新版资源| av视频免费观看在线观看| 九色亚洲精品在线播放| 99九九在线精品视频| 欧美日韩国产mv在线观看视频| 极品少妇高潮喷水抽搐| 免费高清在线观看日韩| 亚洲色图 男人天堂 中文字幕| 欧美中文综合在线视频| 9191精品国产免费久久| 国产xxxxx性猛交| 国产精品 国内视频| 两个人看的免费小视频| 欧美成人精品欧美一级黄| 免费观看av网站的网址| 免费在线观看黄色视频的| 亚洲成人手机| 欧美日韩国产mv在线观看视频| 国产精品久久久久成人av| 午夜日韩欧美国产| 老司机深夜福利视频在线观看 | 欧美黑人精品巨大| 秋霞伦理黄片| 亚洲欧美成人精品一区二区| 深夜精品福利| 精品酒店卫生间| 亚洲成人av在线免费| 中文字幕人妻丝袜制服| 51午夜福利影视在线观看| 亚洲精品乱久久久久久| a级毛片黄视频| 搡老岳熟女国产| 中文字幕另类日韩欧美亚洲嫩草| 在线天堂最新版资源| 国产精品一区二区在线观看99| 精品酒店卫生间| 成人亚洲欧美一区二区av| 天堂中文最新版在线下载| 交换朋友夫妻互换小说| 十八禁人妻一区二区| 91国产中文字幕| 在线观看免费视频网站a站| 久久久精品免费免费高清| 一级爰片在线观看| 国产亚洲av片在线观看秒播厂| 日韩 欧美 亚洲 中文字幕| 午夜免费男女啪啪视频观看| 男女床上黄色一级片免费看| 19禁男女啪啪无遮挡网站| 国产高清不卡午夜福利| 亚洲欧美一区二区三区黑人| 久久天躁狠狠躁夜夜2o2o | 宅男免费午夜| 国产在线免费精品| 国产av精品麻豆| 久久久久久久久久久免费av| 久久鲁丝午夜福利片| 中文字幕另类日韩欧美亚洲嫩草| 男的添女的下面高潮视频| 男的添女的下面高潮视频| 又大又爽又粗| 99热国产这里只有精品6| 十分钟在线观看高清视频www| 一级片'在线观看视频| 精品第一国产精品| 嫩草影院入口| 成年人午夜在线观看视频| 在线观看www视频免费| av线在线观看网站| 欧美av亚洲av综合av国产av | 国产国语露脸激情在线看| 国产男人的电影天堂91| 国产成人av激情在线播放| 亚洲婷婷狠狠爱综合网| 欧美精品亚洲一区二区| 晚上一个人看的免费电影| 亚洲少妇的诱惑av| 国产午夜精品一二区理论片| 女人久久www免费人成看片| 欧美xxⅹ黑人| 亚洲天堂av无毛| 中文精品一卡2卡3卡4更新| 综合色丁香网| 免费在线观看视频国产中文字幕亚洲 | 日韩欧美精品免费久久| 97精品久久久久久久久久精品| 晚上一个人看的免费电影| 精品一区二区三卡| 中文字幕人妻丝袜一区二区 | 成人漫画全彩无遮挡| 咕卡用的链子| 啦啦啦啦在线视频资源| 亚洲国产毛片av蜜桃av| 在线精品无人区一区二区三| 国产熟女欧美一区二区| 成人手机av| 一级片'在线观看视频| 亚洲,一卡二卡三卡| 色婷婷久久久亚洲欧美| 欧美 日韩 精品 国产| 成年动漫av网址| 午夜福利在线免费观看网站| 老鸭窝网址在线观看| 99精品久久久久人妻精品| 国产成人啪精品午夜网站| 嫩草影院入口| 亚洲欧美激情在线| 欧美精品高潮呻吟av久久| 99国产精品免费福利视频| 国产女主播在线喷水免费视频网站| 99香蕉大伊视频| 国产极品粉嫩免费观看在线| 亚洲国产中文字幕在线视频| 99九九在线精品视频| 亚洲精品中文字幕在线视频| 日韩电影二区| 久久久国产精品麻豆| 亚洲精品av麻豆狂野| 色吧在线观看| 国产av国产精品国产| 亚洲成人手机| 热re99久久精品国产66热6| 精品亚洲成a人片在线观看| 精品少妇黑人巨大在线播放| 亚洲av欧美aⅴ国产| 操出白浆在线播放| 成人影院久久| 2021少妇久久久久久久久久久| 亚洲av综合色区一区| 成人午夜精彩视频在线观看| 欧美激情高清一区二区三区 | 好男人视频免费观看在线| 亚洲精品第二区| 美女午夜性视频免费| 人人妻人人澡人人爽人人夜夜| 国产极品天堂在线| 美女扒开内裤让男人捅视频| 日韩欧美精品免费久久| 国产爽快片一区二区三区| 热99久久久久精品小说推荐| 国产伦人伦偷精品视频| 亚洲天堂av无毛| 国产精品女同一区二区软件| 国产黄色视频一区二区在线观看| 国产亚洲av片在线观看秒播厂| 午夜福利免费观看在线| 中文字幕人妻熟女乱码| 日本av手机在线免费观看| 午夜激情av网站| 日韩视频在线欧美| 天堂8中文在线网| 99久国产av精品国产电影| 国产亚洲精品第一综合不卡| 国产一区二区激情短视频 | 自线自在国产av| 一级爰片在线观看| 欧美日韩亚洲综合一区二区三区_| 一区二区av电影网| 午夜福利视频精品| 久久久久久人人人人人| 欧美人与善性xxx| 操出白浆在线播放| 青青草视频在线视频观看| 丰满饥渴人妻一区二区三| 蜜桃在线观看..| 国产精品国产三级专区第一集| 午夜久久久在线观看| 日韩 亚洲 欧美在线| 久久久精品免费免费高清| 亚洲国产欧美一区二区综合| 国产亚洲午夜精品一区二区久久| 美女国产高潮福利片在线看| 美女中出高潮动态图| 国产成人精品无人区| 亚洲精品国产一区二区精华液| 亚洲精品日本国产第一区| 男女无遮挡免费网站观看| 美女大奶头黄色视频| www.精华液| 国产亚洲av高清不卡| 国产成人一区二区在线| 国产精品一国产av| 一区二区三区四区激情视频| 三上悠亚av全集在线观看| 90打野战视频偷拍视频| av片东京热男人的天堂| 美国免费a级毛片| 国产成人系列免费观看| 国产免费福利视频在线观看| 一边亲一边摸免费视频| 精品少妇一区二区三区视频日本电影 | 精品久久久精品久久久| 少妇精品久久久久久久| 国产福利在线免费观看视频| 国产视频首页在线观看| 久久狼人影院| 2018国产大陆天天弄谢| 久久久久久人妻| 最新的欧美精品一区二区| 国产在视频线精品| 亚洲精品美女久久久久99蜜臀 | 99久久精品国产亚洲精品| 老司机靠b影院| 国产有黄有色有爽视频| 多毛熟女@视频| 晚上一个人看的免费电影| 色网站视频免费| 国产男人的电影天堂91| 国产精品国产三级国产专区5o| 啦啦啦 在线观看视频| 日本wwww免费看| 99久国产av精品国产电影| 国产不卡av网站在线观看| 中文字幕人妻熟女乱码| 人妻人人澡人人爽人人| 两个人免费观看高清视频| 国产精品一国产av| 天天躁日日躁夜夜躁夜夜| 午夜免费观看性视频| 国产精品成人在线| 午夜日韩欧美国产| 男女无遮挡免费网站观看| 成人手机av| 天堂俺去俺来也www色官网| 亚洲人成电影观看| 最近2019中文字幕mv第一页| 欧美激情高清一区二区三区 | 亚洲,欧美精品.| 美女扒开内裤让男人捅视频| 日日啪夜夜爽| av免费观看日本| 国产乱来视频区| 电影成人av| 五月天丁香电影| 看十八女毛片水多多多| 日韩av免费高清视频| 三上悠亚av全集在线观看| 永久免费av网站大全| 亚洲色图综合在线观看| 天天影视国产精品| 亚洲熟女精品中文字幕| 色婷婷久久久亚洲欧美| 亚洲精品美女久久av网站| 成人国产av品久久久| 又大又黄又爽视频免费| 午夜激情av网站| 亚洲av日韩精品久久久久久密 | 亚洲,欧美精品.| 日韩大片免费观看网站| 一区二区三区激情视频| 免费观看人在逋| 精品一区二区三区av网在线观看 | 亚洲美女视频黄频| 久久久久国产精品人妻一区二区| 国产精品.久久久| 精品午夜福利在线看| 欧美日韩亚洲高清精品| 欧美精品人与动牲交sv欧美| 少妇猛男粗大的猛烈进出视频| 日韩视频在线欧美| 国产欧美日韩综合在线一区二区| 下体分泌物呈黄色| 欧美最新免费一区二区三区| 两个人看的免费小视频| 日本欧美视频一区| 又大又黄又爽视频免费| 侵犯人妻中文字幕一二三四区| 女人久久www免费人成看片| 一级毛片电影观看| 日本91视频免费播放| 两性夫妻黄色片| 老司机在亚洲福利影院| 欧美日韩综合久久久久久| 黑人欧美特级aaaaaa片| 久久精品熟女亚洲av麻豆精品| 国产精品秋霞免费鲁丝片| 黄网站色视频无遮挡免费观看| 最近最新中文字幕大全免费视频 | 在线观看三级黄色| av线在线观看网站| 亚洲天堂av无毛| 国产亚洲av高清不卡| 成人毛片60女人毛片免费| av国产久精品久网站免费入址| 精品少妇黑人巨大在线播放| svipshipincom国产片| 一个人免费看片子| bbb黄色大片| 亚洲成人一二三区av| 亚洲一区二区三区欧美精品| 久久精品亚洲熟妇少妇任你| 色94色欧美一区二区| 91老司机精品| 国产一卡二卡三卡精品 | 在线观看免费午夜福利视频| 亚洲三区欧美一区| 久久久精品94久久精品| 高清在线视频一区二区三区| 成人黄色视频免费在线看| 精品少妇一区二区三区视频日本电影 | 高清在线视频一区二区三区| 观看av在线不卡| 免费看av在线观看网站| 亚洲av国产av综合av卡| 男人爽女人下面视频在线观看|