News Archive OverviewPaper accepted by New J Phys, 11/22/2017, In collaboration with Prof. Jun Mei's group, we studied the topological phases in water wave systems.Prof. Badreddine Assouar is visiting us, 11/19/2017, Prof. Badreddine Assouar from France is visiting us this week. He will give a seminar on Monday afternoon.Paper accepted by Scientific Reports, 11/8/2017, In this paper, we discussed the high directivity of acoustic source emission by an acoustic metamaterial.Paper accepted by Acta Physica Sinica, 11/3/2017, In this paper, we discussed the multiple topological phases in phononic crystals.Xiujuan defended her thesis, 11/1/2017, Xiujuan successfully passed the defense. Congratulations.Prof. Yia-Chung Chang is visiting us, 10/31/2017, Prof. Yia-Chung Chang from Taiwan is visiting us for two weeks. He will attend Xiujuan's defense and give a seminar on this Tuesday afternoon.Paper accepted by J Appl. Phys, 10/26/2017, This is a review and perspective paper on acoustic metamaterials.Paper accepted by Scientific Reports, 10/24/2017, In this paper, we studied the anisotropy in topological phononic crystals and proposed a design for frequency filter.Prof. Baowen Li and Prof. Jose Sanchez-Dehesa are visiting us, 10/22/2017, Prof. Baowen Li from the US and Prof. Jose Sanchez-Dehesa from Spain are visiting our group this week. They will give two seminars on Tuesday afternoon.Welcome new member, 9/10/2017, Dr. Changqing Xu, graduated from Soochow University joined us today as a postdoctoral research fellow. Welcome.Xiujuan was selected to present her poster, 8/23/2017, Today the deputy prime minister of China, Gaoli Zhang, visited KAUST. Xiujuan was selected to present her research to him.Paper published by J Acoust. Soc. Am, 7/6/2017, In this letter, we described a subwavelength structure that can significantly enhance the emission rate of a low frequency acoustic source. The first author is Dr. Jiajun Zhao. Congratulations to Jiajun.Welcome visiting students, 6/15/2017, Ahmed is a KGSP student and Ali comes from KFUPM. Both of them will stay us until the end of August. Welcome.Dr. Wu received the 2017Phononics Young Investigator Award, 6/8/2017, Dr. Wu received the 2017Phononics Young Investigator Award from the International Phononics Society. She gave an award lecture in the Phoninics 2017 conference.Dr. Wu got promoted, 5/2/2017, The promotion will take effective on July 1st, 2017.Paper accepted by Phys. Rev. A, 3/28/2017, In this paper, we discussed multiple topological phase transitions in a simple photonic crystal. We found the edge states are protected by the topological invariants, spin Chern number, and demonstrated robust one-way propagation of a single helical edge state that are immune to magnetic impurities.Paper published by Optics Express, 2/22/2017, In this paper, we introduce an inverse design process of a metamaterial based on an effective medium we derived earlier to perfectly absorb the oblique incident coherent waves.Paper published by Phys. Rev. A, 12/20/2016, In this work, we discussed a so-called energy balanced material, whose material parameters are both imaginary but the refractive index is real. Such a material is non-Hermitian and can perform as a perfect absorber or a laser. The first author is our VSRP student, Ping Bai.CRG 2016 proposal got funded, 11/17/2016, This project involves Prof. Xixiang Zhang at KAUST, Prof. Xiang Zhang at UC Berkeley, Prof. Nick Fang at MIT and Prof. Liang Feng at SUNY at Buffalo. Congratulations! Positions for PhD student and postdoc research fellows are opening now. Intersted candidates please contact Prof. Wu for details. We are looking for candidates with solid background in wave propagation and excellent analytic and numerical skills.Prof. Badreddine Assouar visited us, 10/23/2016, Prof. Assouar is a renowed physicist in acoustics. He visited us in the past week and gave a seminar about acoustic absorption.Prof. Ross McPhedran visited us, 10/17/2016, Prof. McPhedran is a fellow of Australia Academy of Sciences. He visited our group in the past two weeks and gave a seminar about how 500 million years of mother nature inspired photonics research.Dr. Jiajun Zhao joined us, 9/26/2016, Josh obtained his Bachelor's degree from Nanjing University and PhD degree from National University of Singapore. Welcome!Prof. Luke Bennetts visited us, 9/22/2016, Prof. Luke Bennetts is a senior lecturer in Applied Math at the University of Adelaide in Australia. He visited the WCM group from Sept. 19 to 22. He delivered a seminar about Rayleigh-Bloch wave. The details can be found at https://cemse.kaust.edu.sa/events/Pages/AMCS-Seminar-Luke-Bennetts.aspxPaper published by Scientific Reports, 9/2/2016, In this paper, we report an acoustic analogue of Quantum Spin Hall effect, and demonstrate the topological transition and the topological edge states in a two dimensional acoustic crystal composed of triangular array of core-shell cylinders.Paper accepted by Wave Motion, 8/29/2016, In this paper, we developed a fast algorithm to solve large-scale acoustic scattering problem with finite number of scatterers. The first author of the paper is Pierre-David Letourneau. Prof. Josselin Garnier, Prof. Eric Darve, and Prof. George Papanicolaou are the co-authors.Paper published by Europhysics Letters, 5/18/2016, Ping's paper entitled "multi-channel coherent perfect absorber" is published on EPL today. In this work, we studied various cases in which multiple channel perfect absorption is achieved via either multi-layer cylinders or a cluster of cylinders. Congraduation to Ping.Paper accepted by Physical Review Applied, 5/11/2016, Topological insulators have aroused interest in the study of one-way propagation edge state. In many cases the topological transition occurs when the time-reversal symmetry is broken and is not tunable. In this paper, a design of phononic crystal is proposed. It supports topological transition that can be tuned by varying the geometric size and/or the strength of an external velocity field. The results are universal and may expand our ability to tailor acoustic waves.Prof. Mahmoud Hussein is visiting us, 4/11/2016, Prof. Hussein will give two seminars on energy efficiency. Details are available at: https://cemse.kaust.edu.sa/events/Pages/AMCS%20Seminar-Mahmoud-Hussein.aspxPaper accepted by Appl. Phys. Lett, 1/3/2016, The paper entitled "High Transmission Acoustic Focusing by Impedance-matched Acoustic Meta-surfaces" has been accepted for publication in APL. In this paper, we proposed designs for impedance-matched acoustic metasurfaces to focus acoustic waves in water and air. The acoustic lens in water is designed from space-coiling structure, which is know to have huge impedance-mismatch issues. We improved the structure by using a different filling material to make the effective impedance matched to the background. Such structure does not rely on resonance. Therefore, it is broadband. The acoustic lens in air is designed from layered-structures, in which the input impedance is matched to the air. Both types of lenses can support high energy transmission.Joshua Jianjun Zhao is visiting us, 12/28/2015, Joshua Jiajun Zhao from National University of Singapore is visiting us as a visiting student. He is experienced in acoustic metasurfaces.Paper accepted by Appl. Phys. Express, 12/21/2015, In this paper, we propose a design of graphene-based metamaterials to acheive anisotropic zero-index effective medium parameters, which can be used to guide wave in waveguide bends perfectly. The paper is co-authored by visiting student, Zhaoxian Chen, PhD student, Zeguo Chen, Dr. Ying Wu and other collaborators from Nanjing University.Xiujuan defended her proposal, 7/6/2015, Xiujuan successfully passed her PhD proposal defense. Congratulations to her!Paper accepted by Scientific Reports, 12/16/2014, In this manuscript, we derive an analytical solution to the effective medium parameters of a rectangular array of elliptical scatterers. The theory can reproduce the band structure and transmission spectrum. It can be used in designing metamaterials.Paper published by New Journal of Physics, 12/3/2014, The paper was co-authored by Prof. Jun Mei and Dr. Wu. In this work, we designed an acoustic metasurface that can control the transmitted wave. It can arbitrarily manipulate the directions of the transmitted wave and can also give total reflection even though the impedance is matched to that of the background. The paper was accepted by NJP in October and is published online today.Xiujuan attended ASME IMECE 2014 and received student paper award, 11/17/2014, Xiujuan went to the conference and presented her first-author paper "Semi-Dirac points in phononic crystals". She received student paper award. Congratulations!Paper accepted by Scientific Reports, 10/24/2014, Dr. Wu's collaborative work with Prof. Minghui Lu at Nanjing University has been accepted for publication by Scientific Reports. In this work, we reported acoustic rainbow trapping by using acoustic coiling up spaces connected to a waveguide. Numercial results are compared with the analytic models, both of which show good trapping effect. It may have applications in frequency selection and filtering.Prof Cheng Wei Qiu is visiting us, 9/22/2014, Prof. Cheng Wei Qiu from National University of Singapore is visiting us today and tomorrow. He will deliver a talk about his work.Paper accepted by Phys. Lett. A, 9/13/2014, A paper entitled "Flat Acoustic Lens by Acoustic Grating with Curled Slits", based on Bingmu's thesis work is accepted by Phys. Lett. A today. Congratulations to Pai and Bingmu.Welcome new member, 9/2/2014, Mr. Zhaoxian Chen from Nanjing University joined us as a visiting student. He will be staying here for three months.Xiujuan attended PIERS in Guangzhou, 8/25/2014, Xiujuan attended PIERS in Guangzhou from August 25 to 28. She gave a talk on the anisotropic effective medium theory. Dr. Wu's semi-Dirac point paper was also presented.Prof. Ping Sheng is visiting us, 8/8/2014, Prof. Ping Sheng from HKUST is visiting us for one week.Welcome new member, 8/7/2014, Mr. Zeguo Chen, graduated from Nanjing University, joined us as a PhD student. Welcome aborad.Prof. Dezhuan Han is visiting us, 8/2/2014, Prof. Dezhuan Han from Chongqing University is visiting us now for one week.Paper published by Applied Physics Letters, 7/11/2014, In this work, we studied a double Dirac cone in a phononic crystals with concentric cylinders. We studied the dispersion relations, effective medium and the energy squeezing effect. The first author is Yan Li.Xiujuan attended META'5 in Singapore, 5/19/2014, Xiujuan gave a poster presentation about her effective medium work. Dr. Wu's PRB on Dirac cone, and OE on semi-Dirac point were also delivered as invited talks.Paper accepted by Nanoscale, 5/5/2014, In the paper entitled "Enhanced extraordinary optical transmission (EOT) through arrays of bridged nanohole-pairs and its sensing applications", we studied the roles played by the bridge between subwavelength nanohole pairs on the enhanced optical transmission.Paper accepted by Europhysics Letters, 5/1/2014, In this paper, we design a phononic crystal with rigid scatterers, which give rise to negative effective mass density over a large frequency regime in the low frequency limit. Small devices can be made from such structures.Paper accepted by Applied Physics Letters, 4/15/2014, In this work, we proposed a type of zero-index medium induced by FP resonances, numerically and experimentally demonstrated its cloaking effect.Welcome visiting research interns, 4/14/2014, Ms. Ping Bai and Mr. Haidong Mou from Prof. Yun Lai's group at Soochow University are visiting us through the VSPR program.Prof. Sheng is visiting us, 4/13/2014, Prof. Ping Sheng from HKUST is visiting KAUST with two of his group members. He will give an AMCS seminar about his recent work and a guest lecture in AMCS 353 on a fundamental problem of group velocity in strongly scattering media.Prof. Chang is visiting us, 3/23/2014, Prof. Yia-Chung Chang, (http://www.rcas.sinica.edu.tw/faculty/yiachang.html) is visiting KAUST. He will give an AMCS seminar (http://cemse.kaust.edu.sa/events/Pages/AMCS-Seminar-Chang.aspx) and discuss with people here.Paper accepted by Scientific Reports, 3/4/2014, In this work, we used the perturbation method that was firstly proposed by us (PRB, 86, 035141) to study a double Dirac cone induced by accidental quadrupole-degenerate states in the center of the Brillouin zone. The slope of the linear dispersion and the reduced Hamiltonian are derived. Numerical simulation results show the unique wave propagation behaviors including the Talbot effect. The paper is accepted by Scientific Reports, a journal publised by Nature Publishing Group, and the first-author is Zeguo Chen, an MS student.Paper accepted by Phys. Rev. B, 2/12/2014, "Homogenization scheme for acoustic metamaterials" has been accepted for publication on Physical Review B. In this work, we used the surface response and Green Theorem to obtain effective medium theory that is accurate even beyond the conventional long wavelength constraint.Paper accepted by Optics Express, 1/10/2014, Dr. Wu's recent paper "A semi-Dirac point and an electromagnetic topological transition in a dielectric photonic crystal" got accepted by Optics Express today. In this paper, she studied the classical semi-Dirac point and revealed the relation between a semi-Dirac point and an electromagnetic topological transition. This is the first observation of semi-Dirac point in classical systems. She investigated the linear-parabolic disperion relations and the effective medium of the system. She also demonstrated the drastic change in the wave manipulation behavior across the semi-Dirac point.Dr. Wu attended International Workshop on Wave Functional Materials, 11/12/2013,The workshop was held in Suzhou from 8 to 11 November. Dr. Wu gave a talk there and discussed with many leading scientists in the field.Dr. Wu attended the ISAPS, 10/21/2013, Dr. Wu attended the International symposium on the theory and application of artificial periodic structures in Changsha, China from October 18 to 20. She gave a talk on the k.p method for Dirac and Dirac-like cones in phononic crystals.Welcome Dr. Yanlong Xu join us, 10/20/2013, Dr. Yanlong Xu, graduated from Xi'an Jiaotong University, joined us today. He is focused on the mechanical waves in phononic crystals.Paper published by AIP Advances, 10/18/2013, The paper entitled "A new type of artificial structure to achieve broadband omnidirectional acoustic absorption" has been published online today on AIP Advances. The work was jointly conducted by Dr. Wu and her collaborators at Nanjing University in China. It gives a design for broadband acoustic absorption material based on transformation acoustics.Paper accepted by Europhysics Letters, 10/15/2013, The paper entitled "A lumped model for rotational modes in periodic solid composites" by Pai Peng, Sharefa Asiri, Xiujuan Zhang, Yan Li and Ying Wu has been accepted by Europhysics Letters. In this paper, we reported the modified lumped model that can treat roational motion in metamaterials and reveals the transition from metamaterial to phononic crystals while adjusting the material parameters.Welcome new members, 9/1/2013, Today is the first day of the new semester. Let's welcome two new PhD students: Ms. Xiujuan Zhang and Ms. Rasha Aljadhdali. Ms. Zhang graduated from South China University of Technology with a Master's degree and Ms. Aljadhdali obtained her MS from KAUST.Dr. Wu organized a special session in PIRES, 8/14/2013, PIERS is held at Stockholm from 12 Aug to 15 Aug. Dr. Wu organized a special session on effective medium today.Prof. Ping Sheng is visiting us, 7/26/2013, Prof. Ping Sheng and his PhD student Min Yang will be staying with us for two weeks. Prof. Sheng will give a short course on localization, hopping conduction, graphene. We will be working together on elastic meta-waves.Welcome new members, 6/8/2013, Rasha, Dalal, and Zainab start to do their summmer Directed Research with us today. Welcome and hope they can have a fruitful summer.Bingmu defended her thesis today, 5/7/2013, Bingmu defeneded her thesis entitled " Focusing of acoustic waves through sonic material with subwavelength structures" More than 20 people attended her presentation. Prof. David Keyes and Prof. Gerard Schuster were on her thesis committee. They gave very good comments on her thesis work.Prof. Josselin Garnier and Pierre-David Letourneau visited us, 5/6/2013, Prof. Josselin Garnier from Université Paris VII and doctor-to-be Pierre-David Letourneau form Stanford University gave excellent talks in the workshop. After the workshop, both of them visited us for discussion on different interesting research topics. Pierre will move to Columbia University for his new faculty appointment after his graduation. Congratulations to Pierre and best wishes for him!International workshop on Multiscale Modeling, Simulation and Inversion kicked off today! 5/3/2013 The purpose of this workshop is to discuss the scientific developments, challenges and difficulties in multiscale waveform modeling, simulation and inversion in important industrial applications ranging from seismic imaging and inversion to metamaterial properties to medical tomography. The synergy among these applications will allow transferring the knowledge from one area to another. For details, please visit: http://emang.kaust.edu.sa/Pages/Workshop.aspxPaper accepted by Applied Physics Letters, 4/21/2013, Paper entitled "Total reflection and cloaking by zero index metamaterials loaded with rectangular dielectric defects" got accepted by Applied Physics Letters. In this paper, we analyzed the transmission properity of a zero index metamaterial embedded with rectangular dielectric defects and gave a closed form solution as well as the conditions on total transmission and reflection.Prof. Ping Sheng gave a talk, 4/5/2013, Prof. Ping Sheng, a renowned physicist, gave a very interesting guest lecture about dynamic mass density and their progresses in acoustic metamaterials during his visit to KAUST. He started from the definition of mass density, talked about resonances, explained 3 generations of low-frequency-sound-proof metamaterials.Prof. Yan-Feng Chen from Nanjing University visited us, 3/24/2013, Prof. Yan-Feng Chen, head of the Material Scineces department at Nanjing University, visited us from 21 Mar to 24 Mar. He gave a talk about their progresses in acoustic and optical metamaterials.Paper accepted by Optics Express, 3/7/2013, Yan did the calculation for various cases of accidental degeneracy in photonic crystals when she visited here last year. She sumarized and analyzed the condition for the occurance of linear dispersion relation. The paper was submitted on Jan 4th and got accepted today.Prof. C. T. Chan is visiting us, 1/19/2013, Prof. C. T. Chan is visiting us from Jan 19 to Jan 25. He is invited by KAUST WEP team to give a Science-Fiction lecture series. He will also be staying with us for a couple of days.Prof. Li from University of Nevada is visiting us, 12/7/2012, Prof. Li Jichun, a computational mathematician, is visiting our group now. He is a pioneer in numerical simulations of metamaterials. We seek for common interests in conducting cutting-edge research on metamaterials in both physics and numerical simulations.Dr. Wu visited Nanjing University, 10/25/2012, During the Eid break, Dr. Wu visited Prof. Liang and Prof. Lu as well as their labs at Nanjing University and discussed with them the possible collaboration opportunities. Dr. Wu was impressed very much by their progresses.Dr. Wu gave a lecture, 10/9/2012, Dr. Wu gave a lecture in the Earth Science weekly seminar series. In the talk, she introduced some recent developments in elastic waves and metamaterials.Paper accepted by Physical Review B, 10/2/2012, Our paper entitled "Lumped model for rotational modes in phononic crystals" was accepted by PRB. Congratulations to Pai! In this work, we developed a lumped model that can be used to describe the local rotations in phononic crystlas. The model is based on the mass-spring harmonic system, which is simple and is able to capture the essence of physics of the rotational modes.Paper accepted by Advanced Materials, 9/20/2012, The paper entitled "The bio-assembled nano-composites in conch shells exhibit giant electret hysteresis" has been accepted by Advanced Materials, a high impact journal in material sciences.Website established, 9/18/2012, Welcome to visit this newly established website about our research group.
