Optical time lenses have proven to be very versatile for advanced optical signal processing. Based on a controlled interplay between dispersion and phase-modulation by e.g. four-wave mixing, the processing is phase-preserving, and hence useful for all types of data signals including coherent multi-level modulation formats. This has enabled processing of phase-modulated spectrally efficient data signals, such as orthogonal frequency division multiplexed (OFDM) signals. In that case, a spectral telescope system was used, using two time lenses with different focal lengths (chirp rates), yielding a spectral magnification of the OFDM signal. Utilising such telescopic arrangements, it has become possible to perform a number of interesting functionalities, which will be described in the presentation. This includes conversion from OFDM to Nyquist WDM, compression of WDM channels to a single Nyquist channel and WDM regeneration. These operations require a broad bandwidth nonlinear platform, and novel photonic integrated nonlinear platforms like aluminum gallium arsenide nano-waveguides used for 1.28 Tbaud optical signal processing will be described.
{"title":"Ultrahigh bandwidth signal processing","authors":"L. Oxenløwe","doi":"10.1117/12.2235053","DOIUrl":"https://doi.org/10.1117/12.2235053","url":null,"abstract":"Optical time lenses have proven to be very versatile for advanced optical signal processing. Based on a controlled interplay between dispersion and phase-modulation by e.g. four-wave mixing, the processing is phase-preserving, and hence useful for all types of data signals including coherent multi-level modulation formats. This has enabled processing of phase-modulated spectrally efficient data signals, such as orthogonal frequency division multiplexed (OFDM) signals. In that case, a spectral telescope system was used, using two time lenses with different focal lengths (chirp rates), yielding a spectral magnification of the OFDM signal. Utilising such telescopic arrangements, it has become possible to perform a number of interesting functionalities, which will be described in the presentation. This includes conversion from OFDM to Nyquist WDM, compression of WDM channels to a single Nyquist channel and WDM regeneration. These operations require a broad bandwidth nonlinear platform, and novel photonic integrated nonlinear platforms like aluminum gallium arsenide nano-waveguides used for 1.28 Tbaud optical signal processing will be described.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115727878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Soshenko, V. Vorobyov, Stepan V. Bolshedvorsky, N. Lebedev, A. Akimov, V. Sorokin, A. Smolyaninov
NV center in diamond is attracting a lot of attention in quantum information processing community [1]. Been spin system in clean and well-controlled environment of diamond it shows outstanding performance as quantum memory even at room temperature, spin control with single shot optical readout and possibility to build up quantum registers even on single NV center. Moreover, NV centers could be used as high-resolution sensitive elements of detectors of magnetic or electric field, temperature, tension, force or rotation. For all of these applications collection of the light emitted by NV center is crucial point. There were number of approaches suggested to address this issue, proposing use of surface plasmoms [2], manufacturing structures in diamond [3] etc. One of the key feature of any practically important interface is compatibility with the fiber technology. Several groups attacking this problem using various approaches. One of them is placing of nanodiamonds in the holes of photonic crystal fiber [4], another is utilization of AFM to pick and place nanodiamond on the tapered fiber[5]. We have developed a novel technique of placing a nanodiamond with single NV center on the tapered fiber by controlled transfer of a nanodiamond from one “donor” tapered fiber to the “target” clean tapered fiber. We verify our ability to transfer only single color centers by means of measurement of second order correlation function. With this technique, we were able to double collection efficiency of confocal microscope. The majority of the factors limiting the collection of photons via optical fiber are technical and may be removed allowing order of magnitude improved in collection. We also discuss number of extensions of this technique to all fiber excitation and integration with nanostructures. References: [1] Marcus W. Doherty, Neil B. Manson, Paul Delaney, Fedor Jelezko, Jörg Wrachtrup, Lloyd C.L. Hollenberg , " The nitrogen-vacancy colour centre in diamond," Physics Reports, vol. 528, no. 1, p. 1–45, 2013. [2] A.V. Akimov, A. Mukherjee, C.L. Yu, D.E. Chang, A.S. Zibrov, P.R. Hemmer, H. Park and M.D. Lukin, "Generation of single optical plasmons in metallic nanowires coupled to quantum dots," Nature, vol. 450, p. 402–406, 2007. [3] Michael J. Burek , Yiwen Chu, Madelaine S.Z. Liddy, Parth Patel, Jake Rochman , Srujan Meesala, Wooyoung Hong, Qimin Quan, Mikhail D. Lukin and Marko Loncar High quality-factor optical nanocavities in bulk single-crystal diamond, Nature communications 6718 (2014) [4] Tim Schroder, Andreas W. Schell, Gunter Kewes, Thomas Aichele, and Oliver Benson Fiber-Integrated Diamond-Based Single Photon Source, Nano Lett. 2011, 11, 198-202 [5]Lars Liebermeister, et. al. “Tapered fiber coupling of single photons emitted by a deterministically positioned single nitrogen vacancy center”, Appl. Phys. Lett. 104, 031101 (2014)
金刚石中的NV中心在量子信息处理界备受关注[1]。该自旋系统在清洁、可控的金刚石环境中表现出优异的室温量子记忆性能、单次光学读出自旋控制性能和单次NV中心建立量子寄存器的可能性。此外，NV中心可作为磁场或电场、温度、张力、力或旋转探测器的高分辨率敏感元件。在所有这些应用中，收集NV中心发出的光是关键。有许多方法可以解决这个问题，如使用表面等离子体[2]、金刚石制造结构[3]等。任何实际重要接口的关键特征之一是与光纤技术的兼容性。有几个小组使用不同的方法来解决这个问题。一种是在光子晶体光纤的孔中放置纳米金刚石[4]，另一种是利用AFM在锥形光纤上拾取和放置纳米金刚石[5]。我们开发了一种新的技术，通过控制纳米金刚石从一个“供体”锥形纤维转移到“目标”干净的锥形纤维上，将具有单个NV中心的纳米金刚石放置在锥形纤维上。我们通过测量二阶相关函数来验证我们只传递单个色心的能力。该技术使共聚焦显微镜的采集效率提高了一倍。限制通过光纤收集光子的大多数因素是技术上的，可以消除，使收集的数量级得到改善。我们还讨论了该技术在所有纤维激发和与纳米结构集成方面的扩展。参考文献:[1]Marcus W. Doherty, Neil B. Manson, Paul Delaney, Fedor Jelezko, Jörg Wrachtrup, Lloyd C.L. Hollenberg，“钻石中的氮空位色中心”，物理报告，vol. 528, no. 1。1, p. 1 - 4, 2013。[2]张德德，刘志强，张德德，张志强，刘志强，“金属纳米线与量子点耦合的光等离子体激元的产生”，《光子学报》，vol. 45, p. 391 - 391, 2007。[3]朱一文，马德琳S.Z. Liddy, Michael J. Burek, Jake Rochman, Srujan Meesala，洪宇扬，全齐民，Mikhail D. Lukin, Marko Loncar，单晶金刚石的高质量因子光纳米腔，自然科学学报，2014，[4]Tim Schroder, Andreas W. Schell, Gunter Kewes, Thomas Aichele, Oliver Benson，光纤集成金刚石单光子源，2011,11,198-202“由确定定位的单氮空位中心发射的单光子的锥形光纤耦合”，苹果。理论物理。Lett. 104, 031101 (2014)
{"title":"Toward efficient fiber-based quantum interface (Conference Presentation)","authors":"V. Soshenko, V. Vorobyov, Stepan V. Bolshedvorsky, N. Lebedev, A. Akimov, V. Sorokin, A. Smolyaninov","doi":"10.1117/12.2228692","DOIUrl":"https://doi.org/10.1117/12.2228692","url":null,"abstract":"NV center in diamond is attracting a lot of attention in quantum information processing community [1]. Been spin system in clean and well-controlled environment of diamond it shows outstanding performance as quantum memory even at room temperature, spin control with single shot optical readout and possibility to build up quantum registers even on single NV center. Moreover, NV centers could be used as high-resolution sensitive elements of detectors of magnetic or electric field, temperature, tension, force or rotation. For all of these applications collection of the light emitted by NV center is crucial point. There were number of approaches suggested to address this issue, proposing use of surface plasmoms [2], manufacturing structures in diamond [3] etc. One of the key feature of any practically important interface is compatibility with the fiber technology. Several groups attacking this problem using various approaches. One of them is placing of nanodiamonds in the holes of photonic crystal fiber [4], another is utilization of AFM to pick and place nanodiamond on the tapered fiber[5]. We have developed a novel technique of placing a nanodiamond with single NV center on the tapered fiber by controlled transfer of a nanodiamond from one “donor” tapered fiber to the “target” clean tapered fiber. We verify our ability to transfer only single color centers by means of measurement of second order correlation function. With this technique, we were able to double collection efficiency of confocal microscope. The majority of the factors limiting the collection of photons via optical fiber are technical and may be removed allowing order of magnitude improved in collection. We also discuss number of extensions of this technique to all fiber excitation and integration with nanostructures. References: [1] Marcus W. Doherty, Neil B. Manson, Paul Delaney, Fedor Jelezko, Jörg Wrachtrup, Lloyd C.L. Hollenberg , \" The nitrogen-vacancy colour centre in diamond,\" Physics Reports, vol. 528, no. 1, p. 1–45, 2013. [2] A.V. Akimov, A. Mukherjee, C.L. Yu, D.E. Chang, A.S. Zibrov, P.R. Hemmer, H. Park and M.D. Lukin, \"Generation of single optical plasmons in metallic nanowires coupled to quantum dots,\" Nature, vol. 450, p. 402–406, 2007. [3] Michael J. Burek , Yiwen Chu, Madelaine S.Z. Liddy, Parth Patel, Jake Rochman , Srujan Meesala, Wooyoung Hong, Qimin Quan, Mikhail D. Lukin and Marko Loncar High quality-factor optical nanocavities in bulk single-crystal diamond, Nature communications 6718 (2014) [4] Tim Schroder, Andreas W. Schell, Gunter Kewes, Thomas Aichele, and Oliver Benson Fiber-Integrated Diamond-Based Single Photon Source, Nano Lett. 2011, 11, 198-202 [5]Lars Liebermeister, et. al. “Tapered fiber coupling of single photons emitted by a deterministically positioned single nitrogen vacancy center”, Appl. Phys. Lett. 104, 031101 (2014)","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"75 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130805403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shock waves are well-known nonlinear waves, displaying an abrupt discontinuity. Observation can be made in a lot of physical fields, as in water wave, plasma and nonlinear optics. Shock waves can either break or relax through either catastrophic or regularization phenomena. In this work, we restrain our study to dispersive shock waves. This regularization phenomenon implies the emission of dispersive waves. We demonstrate experimentally and numerically the generation of spatial dispersive shock waves in a nonlocal focusing media. The generation of dispersive shock wave in a focusing media is more problematic than in a defocusing one. Indeed, the modulational instability has to be frustrated to observe this phenomenon. In 2010, the dispersive shock wave was demonstrated experimentally in a focusing media with a partially coherent beam [1]. Another way is to use a nonlocal media [2]. The impact of nonlocality is more important than the modulational instability frustration. Here, we use nematic liquid crystals (NLC) as Kerr-like nonlocal medium. To achieve shock formation, we use the Riemann condition as initial spatial condition (edge at the beam entrance of the NLC cell). In these experimental conditions, we generate, experimentally and numerically, shock waves that relax through the emission of dispersive waves. Associated with this phenomenon, we evidence the emergence of a localized wave that travels through the transverse beam profile. The beam steepness, which is a good indicator of the shock formation, is maximal at the shock point position. This latter follows a power law versus the injected power as in [3]. Increasing the injected power, we found multiple shock points. We have good agreements between the numerical simulations and the experimental results. [1] W. Wan, D. V Dylov, C. Barsi, and J. W. Fleischer, Opt. Lett. 35, 2819 (2010). [2] G. Assanto, T. R. Marchant, and N. F. Smyth, Phys. Rev. A - At. Mol. Opt. Phys. 78, 1 (2008). [3] N. Ghofraniha, L. S. Amato, V. Folli, S. Trillo, E. DelRe, and C. Conti, Opt. Lett. 37, 2325 (2012).
激波是众所周知的非线性波，表现为突然的不连续。可以在许多物理领域进行观测，如水波、等离子体和非线性光学。激波可以通过灾难性现象或正则化现象破裂或松弛。在这项工作中，我们的研究仅限于色散激波。这种正则化现象意味着色散波的发射。我们用实验和数值方法证明了在非局部聚焦介质中空间色散激波的产生。在聚焦介质中，色散冲击波的产生比在散焦介质中更有问题。实际上，要观察到这种现象，必须克服调制不稳定性。2010年，在部分相干光束聚焦介质中实验证明了色散激波[1]。另一种方法是使用非本地媒体[2]。非定域性的影响比调制不稳定性的挫败更重要。在这里，我们使用向列液晶(NLC)作为类克尔非局部介质。为了实现激波的形成，我们使用黎曼条件作为初始空间条件(NLC单元的光束入口边缘)。在这些实验条件下，我们通过实验和数值产生了通过发射色散波而松弛的激波。与这种现象相关联，我们证明了一个局部波的出现，该波通过横向光束剖面传播。梁的陡度在激波点位置最大，是激波形成的一个很好的指标。后者遵循与注入功率的幂律，如[3]所示。增加注入功率，我们发现了多个冲击点。数值模拟结果与实验结果吻合较好。[1]王文杰，王晓明，王晓明，等。中国农业科学与技术，2010,28(1)。[2]刘建军，刘建军，刘建军，等。Rev. A - At。分子光学物理，78,1(2008)。[3]张建军，张建军，张建军，等。中国科学:地球科学，2012(3)。
{"title":"Traveling solitary wave induced by nonlocality in dispersive shock wave generation (Conference Presentation)","authors":"H. Louis, Vincent Odent, E. Louvergneaux","doi":"10.1117/12.2228541","DOIUrl":"https://doi.org/10.1117/12.2228541","url":null,"abstract":"Shock waves are well-known nonlinear waves, displaying an abrupt discontinuity. Observation can be made in a lot of physical fields, as in water wave, plasma and nonlinear optics. Shock waves can either break or relax through either catastrophic or regularization phenomena. In this work, we restrain our study to dispersive shock waves. This regularization phenomenon implies the emission of dispersive waves. We demonstrate experimentally and numerically the generation of spatial dispersive shock waves in a nonlocal focusing media. The generation of dispersive shock wave in a focusing media is more problematic than in a defocusing one. Indeed, the modulational instability has to be frustrated to observe this phenomenon. In 2010, the dispersive shock wave was demonstrated experimentally in a focusing media with a partially coherent beam [1]. Another way is to use a nonlocal media [2]. The impact of nonlocality is more important than the modulational instability frustration. Here, we use nematic liquid crystals (NLC) as Kerr-like nonlocal medium. To achieve shock formation, we use the Riemann condition as initial spatial condition (edge at the beam entrance of the NLC cell). In these experimental conditions, we generate, experimentally and numerically, shock waves that relax through the emission of dispersive waves. Associated with this phenomenon, we evidence the emergence of a localized wave that travels through the transverse beam profile. The beam steepness, which is a good indicator of the shock formation, is maximal at the shock point position. This latter follows a power law versus the injected power as in [3]. Increasing the injected power, we found multiple shock points. We have good agreements between the numerical simulations and the experimental results. [1] W. Wan, D. V Dylov, C. Barsi, and J. W. Fleischer, Opt. Lett. 35, 2819 (2010). [2] G. Assanto, T. R. Marchant, and N. F. Smyth, Phys. Rev. A - At. Mol. Opt. Phys. 78, 1 (2008). [3] N. Ghofraniha, L. S. Amato, V. Folli, S. Trillo, E. DelRe, and C. Conti, Opt. Lett. 37, 2325 (2012).","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128239646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Versatile and easy to implement methods to generate arbitrary optical waveforms at high repetition rates are of considerable interest with applications in optical communications, all-optical signal processing, instrumentation systems and microwave signal manipulation. While shaping sinusoidal, Gaussian or hyperbolic secant intensity profiles is commonly achieved by means of modulators or mode-locked lasers, other pulse profiles such as parabolic, triangular or flat-top shapes still remain challenging to synthesize. In this context, several strategies were already explored. First, the linear pulse shaping is a common method to carve an initial ultrashort pulse train into the desired shape. The line-by-line shaping of a coherent frequency comb made of tens of spectral components was also investigated to generate more complex structures whereas Fourier synthesis of a few discrete frequencies spectrum was exploited to efficiently generate high-fidelity ultrafast periodic intensity profiles. Besides linear shaping techniques, several nonlinear methods were implemented to benefit from the adiabatic evolution of the intensity pulse profile upon propagation in optical fibers. Other examples of efficient methods are based on the photonic generation involving specific Mach-Zehnder modulators, microwave photonic filters as well as frequency-to-time conversion. In this contribution, we theoretically and experimentally demonstrate a new approach enabling the synthesis of periodic high-repetition rate pulses with various intensity profiles ranging from parabola to triangular and flat-top pulses. More precisely by linear phase and amplitude shaping of only four spectral lines is it possible to reach the targeted temporal profile. Indeed, tailoring the input symmetric spectrum only requires the determination of two physical parameters: the phase difference between the inner and outer spectral sidebands and the ratio between the amplitude of these sidebands. Therefore, a systematic bidimensional analysis provides the optimum parameters and also highlights that switching between the different waveforms is achieved by simply changing the spectral phase between the inner and outer sidebands. We successfully validate this concept with the generation of high-fidelity ultrafast periodic waveforms at 40 GHz by shaping with a liquid cristal on insulator a four sideband comb resulting from a phase-modulated continuous wave. In order to reach higher repetition rates, we also describe a new scenario to obtain the required initial spectrum by taking advantage of the four-wave mixing process occurring in a highly nonlinear fiber. This approach is experimentally implemented at a repetition rate of 80-GHz by use of intensity and phase measurements that stress that full-duty cycle, high-quality, triangular, parabolic or flat-top profiles are obtained in full agreement with numerical simulations. The reconfigurable property of this photonic waveform generator is confirmed. Finall
{"title":"80GHz waveform generator by optical Fourier synthesis of four spectral sidebands (Conference Presentation)","authors":"J. Fatome, K. Hammani, B. Kibler, C. Finot","doi":"10.1117/12.2223382","DOIUrl":"https://doi.org/10.1117/12.2223382","url":null,"abstract":"Versatile and easy to implement methods to generate arbitrary optical waveforms at high repetition rates are of considerable interest with applications in optical communications, all-optical signal processing, instrumentation systems and microwave signal manipulation. While shaping sinusoidal, Gaussian or hyperbolic secant intensity profiles is commonly achieved by means of modulators or mode-locked lasers, other pulse profiles such as parabolic, triangular or flat-top shapes still remain challenging to synthesize. In this context, several strategies were already explored. First, the linear pulse shaping is a common method to carve an initial ultrashort pulse train into the desired shape. The line-by-line shaping of a coherent frequency comb made of tens of spectral components was also investigated to generate more complex structures whereas Fourier synthesis of a few discrete frequencies spectrum was exploited to efficiently generate high-fidelity ultrafast periodic intensity profiles. Besides linear shaping techniques, several nonlinear methods were implemented to benefit from the adiabatic evolution of the intensity pulse profile upon propagation in optical fibers. Other examples of efficient methods are based on the photonic generation involving specific Mach-Zehnder modulators, microwave photonic filters as well as frequency-to-time conversion. In this contribution, we theoretically and experimentally demonstrate a new approach enabling the synthesis of periodic high-repetition rate pulses with various intensity profiles ranging from parabola to triangular and flat-top pulses. More precisely by linear phase and amplitude shaping of only four spectral lines is it possible to reach the targeted temporal profile. Indeed, tailoring the input symmetric spectrum only requires the determination of two physical parameters: the phase difference between the inner and outer spectral sidebands and the ratio between the amplitude of these sidebands. Therefore, a systematic bidimensional analysis provides the optimum parameters and also highlights that switching between the different waveforms is achieved by simply changing the spectral phase between the inner and outer sidebands. We successfully validate this concept with the generation of high-fidelity ultrafast periodic waveforms at 40 GHz by shaping with a liquid cristal on insulator a four sideband comb resulting from a phase-modulated continuous wave. In order to reach higher repetition rates, we also describe a new scenario to obtain the required initial spectrum by taking advantage of the four-wave mixing process occurring in a highly nonlinear fiber. This approach is experimentally implemented at a repetition rate of 80-GHz by use of intensity and phase measurements that stress that full-duty cycle, high-quality, triangular, parabolic or flat-top profiles are obtained in full agreement with numerical simulations. The reconfigurable property of this photonic waveform generator is confirmed. Finall","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116419594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Melik-Gaykazyan, A. Shorokhov, M. Shcherbakov, I. Staude, D. Smirnova, A. Miroshnichenko, I. Brener, D. Neshev, A. Fedyanin, Y. Kivshar
Two series of nanodisk arrays were designed. The first one was fabricated out of a silicon-on-insulator (SOI) wafer using electron-beam lithography and a reactive-ion etching process. The top layer of a SOI wafer is a 260-nm layer of monocrystalline (100)-cut silicon. We consider three square 400x400 μm2 arrays distinguished by the disk diameter values – 340, 345 and 360 nm, respectively; the period of the nanodisk ordering in the array amounted to 2.85 μm – this value allows for regarding the disks as isolated ones in terms of optical coupling. The nanodisk diameter choice specifies the magnetic dipolar (MD) resonance wavelength [1]. The second series of arrays was made of a 130-nm hydrogenated amorphous silicon (a-Si:H) film grown by plasma-enhanced chemical vapor deposition on a thin glass substrate. In order to study the nonlinear optical response of the nanodisks and verify the multipole resonances roles, we conducted third-harmonic generation (THG) spectroscopy measurements using a tunable (1.0-1.5 μm) optical parametric oscillator (200 fs pulses with the repetition rate of 76 MHz) pumped by a Ti:Sapphire laser. The laser beam waist diameter was set at 11 μm by an aspheric lens. The full thickness of both the SOI and glass wafers (∼500 μm each) was less than the waist depth. The resulting peak intensity reached the values of about 1 GW/cm2 in the sample plane. The laser beam polarization was linear as controlled by a Glan-Taylor laser prism. The transmitted and collimated THG signal was selected by a set of blue filters and detected by a photomultiplier tube connected with a lock-in amplifier. This signal was proven to be of TH origin by checking its cubic dependence on the pump power and by direct measurements of its spectrum. It was also verified that the THG beam was polarized parallel to the orientation of the pump beam polarization. It should be pointed out that the penetration depth of the THG into silicon does not exceed the nanodisk height. The experimental technique [2] of nonlinear spectroscopy consists of defining the ratio of the TH signal from the nanostructured area to the successively measured signal from the nearby area where the top layer of silicon was etched away (in the case of the SOI wafer) or to the signal from a reference channel (in the case of the a-Si:H film). These ratios reveal the enhanced third-order optical response; moreover, the dispersion of the silicon nonlinear susceptibility is thereby taken into account. The resultant normalized THG signal represents the nanodisks and their resonant contribution. In this contribution, we have shown the third-harmonic response of silicon nanodisks at their electric and magnetic dipolar resonances. The enhanced up-conversion efficiency at the MD resonance of the nanodisks is observed, whereas the electric dipolar resonance yields less nonlinear conversion. The maximum area-normalized THG enhancement is around 30. In this work, the observed linear and nonlinear spectra ar
{"title":"Third harmonic generation in isolated all dielectric meta-atoms (Conference Presentation)","authors":"E. Melik-Gaykazyan, A. Shorokhov, M. Shcherbakov, I. Staude, D. Smirnova, A. Miroshnichenko, I. Brener, D. Neshev, A. Fedyanin, Y. Kivshar","doi":"10.1117/12.2228249","DOIUrl":"https://doi.org/10.1117/12.2228249","url":null,"abstract":"Two series of nanodisk arrays were designed. The first one was fabricated out of a silicon-on-insulator (SOI) wafer using electron-beam lithography and a reactive-ion etching process. The top layer of a SOI wafer is a 260-nm layer of monocrystalline (100)-cut silicon. We consider three square 400x400 μm2 arrays distinguished by the disk diameter values – 340, 345 and 360 nm, respectively; the period of the nanodisk ordering in the array amounted to 2.85 μm – this value allows for regarding the disks as isolated ones in terms of optical coupling. The nanodisk diameter choice specifies the magnetic dipolar (MD) resonance wavelength [1]. The second series of arrays was made of a 130-nm hydrogenated amorphous silicon (a-Si:H) film grown by plasma-enhanced chemical vapor deposition on a thin glass substrate. In order to study the nonlinear optical response of the nanodisks and verify the multipole resonances roles, we conducted third-harmonic generation (THG) spectroscopy measurements using a tunable (1.0-1.5 μm) optical parametric oscillator (200 fs pulses with the repetition rate of 76 MHz) pumped by a Ti:Sapphire laser. The laser beam waist diameter was set at 11 μm by an aspheric lens. The full thickness of both the SOI and glass wafers (∼500 μm each) was less than the waist depth. The resulting peak intensity reached the values of about 1 GW/cm2 in the sample plane. The laser beam polarization was linear as controlled by a Glan-Taylor laser prism. The transmitted and collimated THG signal was selected by a set of blue filters and detected by a photomultiplier tube connected with a lock-in amplifier. This signal was proven to be of TH origin by checking its cubic dependence on the pump power and by direct measurements of its spectrum. It was also verified that the THG beam was polarized parallel to the orientation of the pump beam polarization. It should be pointed out that the penetration depth of the THG into silicon does not exceed the nanodisk height. The experimental technique [2] of nonlinear spectroscopy consists of defining the ratio of the TH signal from the nanostructured area to the successively measured signal from the nearby area where the top layer of silicon was etched away (in the case of the SOI wafer) or to the signal from a reference channel (in the case of the a-Si:H film). These ratios reveal the enhanced third-order optical response; moreover, the dispersion of the silicon nonlinear susceptibility is thereby taken into account. The resultant normalized THG signal represents the nanodisks and their resonant contribution. In this contribution, we have shown the third-harmonic response of silicon nanodisks at their electric and magnetic dipolar resonances. The enhanced up-conversion efficiency at the MD resonance of the nanodisks is observed, whereas the electric dipolar resonance yields less nonlinear conversion. The maximum area-normalized THG enhancement is around 30. In this work, the observed linear and nonlinear spectra ar","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114142195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A soliton explosion is a dramatic effect, whereby a pulse circulating in a mode-locked laser dissipates and then remarkably reforms within a few roundtrips. Our group recently reported the first observation of such explosions in an all-fibre laser. Here, we expand on our initial work, reporting a detailed numerical and experimental study of the dynamics and characteristics of soliton explosions. Our experiment is based on a passively mode-locked Yb-doped fiber laser, where explosions occur close to the boundary between stable and noise-like operation. To capture the events, we use the dispersive Fourier transformation to record, in real time, the pulse-to-pulse spectra emitted by the laser. We explore a variety of operating conditions by systematically adjusting the laser pump power and its cavity length. We also use a realistic model based on a set of generalized nonlinear Schrodinger equations to simulate the explosion dynamics. We find that the explosion dynamics can be influenced by adjusting the operating conditions. As a general trend, the frequency of the events increases as the conditions move closer to the boundary of unstable operation. In fact, when sufficiently close to the boundary, the “explosions” can even become more frequent than ordinary pulses. Moreover, our simulations reveal that complex features in the spectral and temporal profiles of the explosion events can be explained in terms of a multi-pulsing instability. Finally we have examined how the statistics of the events depend on the laser geometry and also whether such explosions indicate the existence of a “strange attractor”.
{"title":"Experimental observations of soliton explosions in ultrafast fibre lasers (Conference Presentation)","authors":"N. Broderick, A. Runge, M. Erkintalo","doi":"10.1117/12.2227447","DOIUrl":"https://doi.org/10.1117/12.2227447","url":null,"abstract":"A soliton explosion is a dramatic effect, whereby a pulse circulating in a mode-locked laser dissipates and then remarkably reforms within a few roundtrips. Our group recently reported the first observation of such explosions in an all-fibre laser. Here, we expand on our initial work, reporting a detailed numerical and experimental study of the dynamics and characteristics of soliton explosions. Our experiment is based on a passively mode-locked Yb-doped fiber laser, where explosions occur close to the boundary between stable and noise-like operation. To capture the events, we use the dispersive Fourier transformation to record, in real time, the pulse-to-pulse spectra emitted by the laser. We explore a variety of operating conditions by systematically adjusting the laser pump power and its cavity length. We also use a realistic model based on a set of generalized nonlinear Schrodinger equations to simulate the explosion dynamics. We find that the explosion dynamics can be influenced by adjusting the operating conditions. As a general trend, the frequency of the events increases as the conditions move closer to the boundary of unstable operation. In fact, when sufficiently close to the boundary, the “explosions” can even become more frequent than ordinary pulses. Moreover, our simulations reveal that complex features in the spectral and temporal profiles of the explosion events can be explained in terms of a multi-pulsing instability. Finally we have examined how the statistics of the events depend on the laser geometry and also whether such explosions indicate the existence of a “strange attractor”.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129985764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Gilles, J. Nuño, M. Guasoni, B. Kibler, C. Finot, J. Fatome
The generation of picosecond pulse trains has become of great interest for many scientific applications. However, even though different techniques of nonlinear compression have been developed for optical fibers in the anomalous dispersion regime, only a few exist for normally dispersive fibers. Here, we describe a new method based on the generation of a strong nonlinear focusing effect induced by the cross phase modulation of a high power 40-GHz beat-signal on its orthogonally polarized interleaved weak replica. More precisely, while the normally dispersive defocusing regime induced a nonlinear reshaping of a high power 40-GHz sinusoidal signal into successively parabolic then broad and sharp square pulses, it also progressively close a singularity at its null point characterized by steeper and steeper edges. Here we show that the cross phase modulation induced by this nonlinear dark structure on a weak interleaved orthogonally polarized replica then turns out the normally dispersive regime into a focusing dynamics. This phenomenon is similar to the polarization domain wall effect for which the energy of a domain is strongly localized and bounded by the commutation of both orthogonally polarized waves. In other words, since a particle in a gradually collapsing potential, the energy contained in the weak interleaved component is found to be more and more bounded and is thus forced to temporally compress along the fiber length, thus reshaping the initial beat-signal into a train of well-separated short pulses. We have experimentally validated the present method by demonstrating the temporal compression of an initial 40-GHz beat-signal into a train of well separated pulses in different types of normally dispersive fibers. To this aim, an initial 40-GHz beat-signal is first split into 2 replica for which one is half-period delayed and 10-dB attenuated before polarization multiplexing in such a way to generate a strongly-unbalanced orthogonally-polarized interleaved signal. The resulting signal is then amplified and injected into the fiber under-test. In first fibers of 1 and 2 km (D = -15 ps.km-1.nm-1, γ = 2.3 W-1.km-1, α = 0.2 dB.km-1), we have observed the nonlinear focusing of the initial 40-GHz sinusoidal signal input into a train of 5.5-ps pulses. By decreasing the dispersion coefficient down to D = -2.5 ps.km-1.nm-1 in such a way to exacerbate the nonlinear defocusing effect of the strongest component far beyond the wave breaking, we have successfully compressed the orthogonally polarized 40-GHz beat-signal into well-separated 2.5-ps pulses after 5 km of propagation for a total input power of 28 dBm. We then studied the effect of total power on the compression ratio, and showed that compression is more efficient with higher total power, even after the wave breaking phenomenon. We followed by showing that the power ratio between the two polarization axes is closely linked to the compression factor, as the higher the power difference between the
{"title":"40GHz picosecond pulse source based on a cross-phase modulation induced orthogonal focusing in normally dispersive optical fibers (Conference Presentation)","authors":"M. Gilles, J. Nuño, M. Guasoni, B. Kibler, C. Finot, J. Fatome","doi":"10.1117/12.2227684","DOIUrl":"https://doi.org/10.1117/12.2227684","url":null,"abstract":"The generation of picosecond pulse trains has become of great interest for many scientific applications. However, even though different techniques of nonlinear compression have been developed for optical fibers in the anomalous dispersion regime, only a few exist for normally dispersive fibers. Here, we describe a new method based on the generation of a strong nonlinear focusing effect induced by the cross phase modulation of a high power 40-GHz beat-signal on its orthogonally polarized interleaved weak replica. More precisely, while the normally dispersive defocusing regime induced a nonlinear reshaping of a high power 40-GHz sinusoidal signal into successively parabolic then broad and sharp square pulses, it also progressively close a singularity at its null point characterized by steeper and steeper edges. Here we show that the cross phase modulation induced by this nonlinear dark structure on a weak interleaved orthogonally polarized replica then turns out the normally dispersive regime into a focusing dynamics. This phenomenon is similar to the polarization domain wall effect for which the energy of a domain is strongly localized and bounded by the commutation of both orthogonally polarized waves. In other words, since a particle in a gradually collapsing potential, the energy contained in the weak interleaved component is found to be more and more bounded and is thus forced to temporally compress along the fiber length, thus reshaping the initial beat-signal into a train of well-separated short pulses. We have experimentally validated the present method by demonstrating the temporal compression of an initial 40-GHz beat-signal into a train of well separated pulses in different types of normally dispersive fibers. To this aim, an initial 40-GHz beat-signal is first split into 2 replica for which one is half-period delayed and 10-dB attenuated before polarization multiplexing in such a way to generate a strongly-unbalanced orthogonally-polarized interleaved signal. The resulting signal is then amplified and injected into the fiber under-test. In first fibers of 1 and 2 km (D = -15 ps.km-1.nm-1, γ = 2.3 W-1.km-1, α = 0.2 dB.km-1), we have observed the nonlinear focusing of the initial 40-GHz sinusoidal signal input into a train of 5.5-ps pulses. By decreasing the dispersion coefficient down to D = -2.5 ps.km-1.nm-1 in such a way to exacerbate the nonlinear defocusing effect of the strongest component far beyond the wave breaking, we have successfully compressed the orthogonally polarized 40-GHz beat-signal into well-separated 2.5-ps pulses after 5 km of propagation for a total input power of 28 dBm. We then studied the effect of total power on the compression ratio, and showed that compression is more efficient with higher total power, even after the wave breaking phenomenon. We followed by showing that the power ratio between the two polarization axes is closely linked to the compression factor, as the higher the power difference between the ","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126894805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Simonsen, Y. Tsaturyan, Yannick Seis, S. Schmid, A. Schliesser, E. Polzik
Recent advances in the fabrication of nano- and micromechanical elements enable the realization of high-quality mechanical resonators with masses so small that the forces from optical photons can have a significant impact on their motion. This facilitates a strong interaction between mechanical motion and light, or phonons and photons. This interaction is the corner stone of the field of optomechanics and allows, for example, for ultrasensitive detection and manipulation of mechanical motion using laser light. Remarkably, today these techniques can be extended into the quantum regime, in which fundamental fluctuations of light and mechanics govern the system’s behavior. Micromechanical elements can also interact strongly with other physical systems, which is the central aspect of many micro-electro-mechanical based sensors. Micromechanical elements can therefore act as a bridge between these diverse systems, plus technologies that utilize them, and the mature toolbox of optical techniques that routinely operates at the quantum limit. In a previous work [1], we demonstrated such a bridge by realizing simultaneous coupling between an electronic LC circuit and a quantum-noise limited optical interferometer. The coupling was mediated by a mechanical oscillator forming a mechanically compliant capacitor biased with a DC voltage. The latter enhances the electromechanical interaction all the way to the strong coupling regime. That scheme allowed optical detection of electronic signals with effective noise temperatures far below the actual temperature of the mechanical element. On-chip integration of the electrical, mechanical and optical elements is necessary for an implementation of the transduction scheme that is viable for commercial applications. Reliable assembly of a strongly coupled electromechanical device, and inclusion of an optical cavity for enhanced optical readout, are key features of the new platform. Both can be achieved with standard cleanroom fabrication techniques. We will furthermore present ongoing work to couple our transducer to an RF or microwave antenna, for low-noise detection of electromagnetic signals, including sensitive measurements of magnetic fields in an MRI detector. Suppression of thermomechanical noise is a key feature of electro-optomechanical transducers, and, more generally, hybrid systems involving mechanical degrees of freedom. We have shown that engineering of the phononic density of states allows improved isolation of the relevant mechanical modes from their thermal bath [2], enabling coherence times sufficient to realize quantum-coherent optomechanical coupling. This proves the potential of the employed platform for complex transducers all the way into the quantum regime. References: [1] Bagci et al, Nature 507, 81–85, (06 March 2014) [2] Tsaturyan, et al., Optics Express, Vol. 22, Issue 6, pp. 6810-6821 (2014)
纳米和微机械元件制造的最新进展使高质量的机械谐振器得以实现，其质量如此之小，以至于光子的力可以对它们的运动产生重大影响。这促进了机械运动与光，或声子与光子之间的强烈相互作用。这种相互作用是光力学领域的基石，并且允许使用激光进行超灵敏检测和操纵机械运动。值得注意的是，今天这些技术可以扩展到量子状态，在量子状态中，光和力学的基本波动控制着系统的行为。微机械元件也可以与其他物理系统强烈相互作用，这是许多基于微机电的传感器的核心方面。因此，微机械元件可以作为这些不同系统之间的桥梁，以及利用它们的技术，以及在量子极限下常规操作的成熟光学技术工具箱。在之前的工作[1]中，我们通过实现电子LC电路和量子噪声限制光学干涉仪之间的同时耦合来演示这种桥。耦合由一个机械振荡器介导，形成一个带有直流电压偏置的机械柔性电容器。后者将机电相互作用一直增强到强耦合状态。该方案允许光学检测电子信号的有效噪声温度远低于机械元件的实际温度。芯片上集成的电气，机械和光学元件是必要的转导方案的实施是可行的商业应用。强耦合机电设备的可靠组装以及用于增强光学读出的光学腔是新平台的关键特征。两者都可以通过标准的洁净室制造技术来实现。我们将进一步介绍正在进行的工作，将我们的换能器与射频或微波天线耦合，用于电磁信号的低噪声检测，包括MRI检测器中磁场的敏感测量。热机械噪声的抑制是光电机械换能器的一个关键特征，更普遍的是，涉及机械自由度的混合系统。我们已经证明，态声子密度的工程可以改善相关机械模式与其热浴的隔离[2]，使相干时间足够实现量子相干光力学耦合。这证明了所采用的复杂换能器平台一直进入量子状态的潜力。参考文献:[1]Bagci et al.， Nature 507,81 - 85，(2014年3月6日)[2]Tsaturyan et al.， Optics Express Vol. 22, Issue 6, pp. 6810-6821 (2014)
{"title":"On-chip RF-to-optical transducer (Conference Presentation)","authors":"A. Simonsen, Y. Tsaturyan, Yannick Seis, S. Schmid, A. Schliesser, E. Polzik","doi":"10.1117/12.2229012","DOIUrl":"https://doi.org/10.1117/12.2229012","url":null,"abstract":"Recent advances in the fabrication of nano- and micromechanical elements enable the realization of high-quality mechanical resonators with masses so small that the forces from optical photons can have a significant impact on their motion. This facilitates a strong interaction between mechanical motion and light, or phonons and photons. This interaction is the corner stone of the field of optomechanics and allows, for example, for ultrasensitive detection and manipulation of mechanical motion using laser light. Remarkably, today these techniques can be extended into the quantum regime, in which fundamental fluctuations of light and mechanics govern the system’s behavior. Micromechanical elements can also interact strongly with other physical systems, which is the central aspect of many micro-electro-mechanical based sensors. Micromechanical elements can therefore act as a bridge between these diverse systems, plus technologies that utilize them, and the mature toolbox of optical techniques that routinely operates at the quantum limit. In a previous work [1], we demonstrated such a bridge by realizing simultaneous coupling between an electronic LC circuit and a quantum-noise limited optical interferometer. The coupling was mediated by a mechanical oscillator forming a mechanically compliant capacitor biased with a DC voltage. The latter enhances the electromechanical interaction all the way to the strong coupling regime. That scheme allowed optical detection of electronic signals with effective noise temperatures far below the actual temperature of the mechanical element. On-chip integration of the electrical, mechanical and optical elements is necessary for an implementation of the transduction scheme that is viable for commercial applications. Reliable assembly of a strongly coupled electromechanical device, and inclusion of an optical cavity for enhanced optical readout, are key features of the new platform. Both can be achieved with standard cleanroom fabrication techniques. We will furthermore present ongoing work to couple our transducer to an RF or microwave antenna, for low-noise detection of electromagnetic signals, including sensitive measurements of magnetic fields in an MRI detector. Suppression of thermomechanical noise is a key feature of electro-optomechanical transducers, and, more generally, hybrid systems involving mechanical degrees of freedom. We have shown that engineering of the phononic density of states allows improved isolation of the relevant mechanical modes from their thermal bath [2], enabling coherence times sufficient to realize quantum-coherent optomechanical coupling. This proves the potential of the employed platform for complex transducers all the way into the quantum regime. References: [1] Bagci et al, Nature 507, 81–85, (06 March 2014) [2] Tsaturyan, et al., Optics Express, Vol. 22, Issue 6, pp. 6810-6821 (2014)","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133137398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Geiger, I. Dutta, D. Savoie, B. Fang, Carlos Guarrido Alzar, B. Venon, A. Landragin
We report the first operation of a cold atom inertial sensor without dead time. Dead times in conventional cold atom interferometers originate from the preparation of a cold atom source prior to its injection in the interferometer and where information on inertial signals is lost. We use a sequence where we simultaneously prepare a cold atom source and operate a light pulse atom interferometer to circumvent the dead time limitation. Therefore the sensor continuously captures all the dynamics with respect to an inertial frame. We show that the continuous operation does not degrade the sensitivity and stability of the atom interferometer, by demonstrating a rotation sensitivity level of less than 1 nrad/s after 10 000 s of integration time. Such a sensitivity level improves previous results by more than an order of magnitude and opens applications of cold atom gyroscopes in inertial navigation and geophysics.
{"title":"Continuous cold atom inertial sensor with 1 nrad.s-1 rotation stability(Conference Presentation)","authors":"R. Geiger, I. Dutta, D. Savoie, B. Fang, Carlos Guarrido Alzar, B. Venon, A. Landragin","doi":"10.1117/12.2228533","DOIUrl":"https://doi.org/10.1117/12.2228533","url":null,"abstract":"We report the first operation of a cold atom inertial sensor without dead time. Dead times in conventional cold atom interferometers originate from the preparation of a cold atom source prior to its injection in the interferometer and where information on inertial signals is lost. We use a sequence where we simultaneously prepare a cold atom source and operate a light pulse atom interferometer to circumvent the dead time limitation. Therefore the sensor continuously captures all the dynamics with respect to an inertial frame. We show that the continuous operation does not degrade the sensitivity and stability of the atom interferometer, by demonstrating a rotation sensitivity level of less than 1 nrad/s after 10 000 s of integration time. Such a sensitivity level improves previous results by more than an order of magnitude and opens applications of cold atom gyroscopes in inertial navigation and geophysics.","PeriodicalId":285152,"journal":{"name":"SPIE Photonics Europe","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126037068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Kalchmair, R. Gansch, P. Genevet, T. Zederbauer, D. Macfarland, H. Detz, A. Andrews, W. Schrenk, G. Strasser, F. Capasso, M. Lončar
Photonic crystal slabs have been subject to research for more than a decade, yet the existence of bound states in the radiation continuum (BICs) in photonic crystals has been reported only recently [1]. A BIC is formed when the radiation from all possible channels interferes destructively, causing the overall radiation to vanish. In photonic crystals, BICs are the result of accidental phase matching between incident, reflected and in-plane waves at seemingly random wave vectors [2]. While BICs in photonic crystals have been discussed previously using reflection measurements, we reports for the first time in-situ measurements of the bound states in the continuum in photonic crystal slabs. By embedding a photodetector into a photonic crystal slab we were able to directly observe optical BICs. The photonic crystal slabs are processed from a GaAs/AlGaAs quantum wells heterostructure, providing intersubband absorption in the mid-infrared wavelength range. The generated photocurrent is collected via doped contact layers on top and bottom of the suspended photonic crystal slab. We were mapping out the photonic band structure by rotating the device and by acquiring photocurrent spectra every 5°. Our measured photonic bandstructure revealed several BICs, which was confirmed with a rigorously coupled-wave analysis simulation. Since coupling to external fields is suppressed, the photocurrent measured by the photodetector vanishes at the BIC wave vector. To confirm the relation between the measured photocurrent and the Q-factor we used temporal coupled mode theory, which yielded an inverse proportional relation between the photocurrent and the out-coupling loss from the photonic crystal. Implementing a plane wave expansion simulation allowed us to identify the corresponding photonic crystal modes. The ability to directly measure the field intensity inside the photonic crystal presents an important milestone towards integrated opto-electronic BIC devices. Potential applications range include nonlinear optics, nano-optics, sensing and optical computing. This research was supported by the Austrian Science Fund FWF (Grant No. F2503-N17), the PLATON project 35N, the “Gesellschaft für Mikro- und Nanoelektronik” GMe and the European Research Council (Grant no. 639109). [1] C.W. Hsu et al. “Observation of trapped light within the radiation continuum”, Nature 499, 188 (2013) [2] Y. Yang Y et al., “Analytical Perspective for Bound States in the Continuum in Photonic Crystal Slabs”, Phys Rev Lett 113, 037401 (2014)
光子晶体板的研究已经进行了十多年，但光子晶体中辐射连续体(bic)中束缚态的存在直到最近才被报道[1]。当来自所有可能通道的辐射发生破坏性干扰，导致整体辐射消失时，BIC就形成了。在光子晶体中，bic是入射波、反射波和平面波在看似随机的波矢量上偶然相位匹配的结果[2]。虽然光子晶体中的BICs先前已经使用反射测量进行了讨论，但我们首次报道了在光子晶体板中连续统中的束缚态的原位测量。通过将光电探测器嵌入光子晶体板中，我们能够直接观察光学bic。光子晶体板由GaAs/AlGaAs量子阱异质结构加工而成，在中红外波长范围内提供子带间吸收。产生的光电流通过悬浮光子晶体板顶部和底部的掺杂接触层收集。我们通过旋转器件和每5°获取光电流光谱来绘制光子带结构。我们测量的光子带结构显示了几个bic，并通过严格耦合波分析模拟证实了这一点。由于与外场的耦合被抑制，光电探测器测量的光电流在BIC波矢量处消失。为了确定测量的光电流与q因子之间的关系，我们使用了时间耦合模式理论，该理论得出了光电流与光子晶体的外耦合损耗成反比关系。通过平面波展开模拟，我们可以识别出相应的光子晶体模式。直接测量光子晶体内部场强的能力是集成光电BIC器件的一个重要里程碑。潜在的应用范围包括非线性光学、纳米光学、传感和光计算。本研究由奥地利科学基金(FWF)资助。F2503-N17)， PLATON项目35N，“德国纳米电子技术研究与发展协会”(Gesellschaft fr Mikro- und Nanoelektronik)和欧洲研究理事会(批准号:639109)。[1]徐春伟等，“辐射连续介质中捕获光的观测”，《自然》，49,188(2013).[2]杨勇等，“光子晶体板连续介质中束缚态的分析”，物理学报，113,037401 (2014)
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