Terahertz Emitters, Receivers, and Applications IX最新文献

Terahertz Emitters, Receivers, and Applications IX Pub Date : 2018-10-29 DOI: 10.1117/12.2516580

引用次数: 0

Broadband terahertz polarization conversion using metasurfaces (Conference Presentation) 使用超表面的宽带太赫兹偏振转换(会议报告)

Terahertz Emitters, Receivers, and Applications IX Pub Date : 2018-09-18 DOI: 10.1117/12.2322496

Houtong Chen, Chun-Chieh Chang

{"title":"Broadband terahertz polarization conversion using metasurfaces (Conference Presentation)","authors":"Houtong Chen, Chun-Chieh Chang","doi":"10.1117/12.2322496","DOIUrl":"https://doi.org/10.1117/12.2322496","url":null,"abstract":"Two-dimensional metamaterials - metasurfaces - offer tremendous opportunities in realizing exotic optical phenomena and functionalities to address the technological challenges encountered in the terahertz frequency regime. By tailoring the resonant response of basic building blocks as well as their mutual interactions, we are able to effectively control of amplitude, phase, and polarization state of terahertz waves. Here we report the realization of highly efficient polarization conversions including: (1) Reflective linear polarization rotation using an array of anisotropic resonators backed with a ground plane; (2) Transmissive linear polarization rotation using an array of anisotropic resonator array sandwiched by two orthogonal gratings; and (3) Reflective linear-to-circular polarization conversion using two cascading arrays of complementary resonators. They operate over a broad bandwidth more than one octave and approaching two octaves in some cases. We further show that the linear polarization rotation is accompanied by a tunable phase discontinuity, which allows us to demonstrate an ultrathin terahertz flat lens enabling diffraction-limited focusing. The broadband linear-to-circular polarization may also find applications including terahertz circular dichroism spectroscopy and excitation of valley polarization in 2D materials.","PeriodicalId":247740,"journal":{"name":"Terahertz Emitters, Receivers, and Applications IX","volume":"26 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120902260","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}

引用次数: 1

Terahertz quantum metamaterials (Conference Presentation) 太赫兹量子超材料(会议报告)

Terahertz Emitters, Receivers, and Applications IX Pub Date : 2018-09-18 DOI: 10.1117/12.2322181

R. Averitt

引用次数: 0

Evaluation of semiconductor materials and devices by laser-induced terahertz emissions (Conference Presentation) 激光诱导太赫兹辐射对半导体材料和器件的评价(会议报告)

Terahertz Emitters, Receivers, and Applications IX Pub Date : 2018-09-18 DOI: 10.1117/12.2322900

I. Kawayama

引用次数: 0

Polarization characteristics of terahertz wave generated by differential frequency mixing under exciton excitation condition in a semiconductor quantum well (Conference Presentation) 半导体量子阱中激子激励下差频混合产生的太赫兹波的偏振特性(会议报告)

Terahertz Emitters, Receivers, and Applications IX Pub Date : 2018-09-18 DOI: 10.1117/12.2319185

O. Kojima

{"title":"Polarization characteristics of terahertz wave generated by differential frequency mixing under exciton excitation condition in a semiconductor quantum well (Conference Presentation)","authors":"O. Kojima","doi":"10.1117/12.2319185","DOIUrl":"https://doi.org/10.1117/12.2319185","url":null,"abstract":"As continuous wave (CW) terahertz (THz) sources, the differential-frequency-mixing (DFM) has an advantage for the frequency tunability by changing the energy separation of the two lasers. In particular, considering the inhomogeneous width in the quantum conﬁnement systems, use of the exciton lines enables wide frequency tuning. The THz sources with the narrow bandwidth and wide frequency tunability will be applied to the high resolution THz spectroscopy. Recently, we realized the CW-THz wave generation by DFM under the exciton excitation conditions in a GaAs/AlAs multiple quantum well (MQW), which shows the wide frequency tuning range over 18 THz. Therefore, in this work, we report the polarization characteristics of a continuous THz electromagnetic wave generated by DFM due to excitation of two exciton states in the GaAs/AlAs multiple quantum well. As a sample, we used an undoped GaAs/AlAs MQW embedded in a p-i-n structure on a (001) n+-GaAs substrate. The thickness of GaAs and AlAs layer is 7.5 nm. The measurements of the THz wave were carried out at 296 K. As the laser sources, a semiconductor laser and a CW-mode Ti:sapphire laser to change the excitation energy were used. The two beams were focused on the sample surface. Comparing the polarization of the laser beams with that of the THz wave, the conversion process from the laser lights to the THz wave via the exciton states, such as the heavy hole and light hole excitons split by quantum confined effects, will be demonstrated.","PeriodicalId":247740,"journal":{"name":"Terahertz Emitters, Receivers, and Applications IX","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132047612","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}

引用次数: 0

Modelling the carrier dynamics of semiconductors to understand their terahertz emission (Conference Presentation) 模拟半导体的载流子动力学以理解它们的太赫兹发射(会议报告)

Terahertz Emitters, Receivers, and Applications IX Pub Date : 2018-09-18 DOI: 10.1117/12.2321155

E. Castro-Camus, M. Alfaro-Gomez, S. C. Corzo-Garcia, A. Hernandez-Serrano, O. Mitrofanov

{"title":"Modelling the carrier dynamics of semiconductors to understand their terahertz emission (Conference Presentation)","authors":"E. Castro-Camus, M. Alfaro-Gomez, S. C. Corzo-Garcia, A. Hernandez-Serrano, O. Mitrofanov","doi":"10.1117/12.2321155","DOIUrl":"https://doi.org/10.1117/12.2321155","url":null,"abstract":"We use a Monte-Carlo model to simulate semi-classical photo-carrier dynamics on bulk InAs, InGaAs and GaAs that leads to terahertz emission after ultrafast photoexcitation. This detailed model has allowed us to understand various aspects of the THz emission process, including the near-field distribution which has been experimentally observed, the role of the excess excitation photon energy, and the relative importance of the surface field driven, diffusive (photo-Dember) and ballistic currents. \u0000In order to understand the near-field emission we coupled a finite-difference time-domain routine to the carrier dynamics simulation, by doing this, we were able to analyse the near terahertz field emission caused by the motion of such carriers even when the excitation is performed at normal incidence. We found that both the current parallel, which has traditionally been assumed not to take part in the emission, and normal to the interface take a relevant role in the terahertz generation. We performed another set of simulations for different bandgaps and excitation-photon energies in order to compare the emission power of all three semiconductors as function of excitation photon energy finding that the carrier excess excitation energy is more relevant to explain their performance difference than their motilities. We conclude that ballistic transport after photoexcitation is the dominant mechanism for terahertz emission instead of diffusion driven or surface field driven charge separation, which were traditionally considered the most relevant mechanisms.","PeriodicalId":247740,"journal":{"name":"Terahertz Emitters, Receivers, and Applications IX","volume":"110 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121529528","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}

引用次数: 0

THz control of magnetism with metamaterials (Conference Presentation) 用超材料控制太赫兹磁场(会议报告)

Terahertz Emitters, Receivers, and Applications IX Pub Date : 2018-09-18 DOI: 10.1117/12.2318098

S. Bonetti

{"title":"THz control of magnetism with metamaterials (Conference Presentation)","authors":"S. Bonetti","doi":"10.1117/12.2318098","DOIUrl":"https://doi.org/10.1117/12.2318098","url":null,"abstract":"Understanding how spins move at pico- and femtosecond time scales is the focus of much of contemporary research in magnetism. I will go through some basic and more advanced concepts in the exciting emerging field of terahertz (THz) magnetism, where electromagnetic radiation in the 0.1-10 THz range, the so-called THz gap, is used to probe or to control spin dynamics at these time scales.\u0000\u0000I will give an overview of the current research in THz magnetism. As illustrating examples, I will briefly discuss how low-intensity THz radiation can be used to probe the fundamentals of spin- dependent transport in the linear regime [1]. I will then describe how intense THz fields can be used to drive coherent and incoherent ultrafast spin dynamics in nonlinear regimes, both with broadband [2] and narrowband radiation [3].\u0000\u0000Finally, I will show some recent implementation of metamaterials [4] aimed at selectively enhancing the terahertz magnetic field in the near-field [5]. I will also illustrate the design of an anti-reflection coating that allows for table-top, femtosecond pump-probe experiments in generic nanostructures surrounded by highly reflective metamaterials [6].\u0000\u0000[1] Z. Jin et al., Nature Physics 11, 761 (2015)\u0000[2] S. Bonetti et al, Physical Review Letters 117, 087205 (2016)\u0000[3] Z. Wang et al., Selective THz control of magnetic order: new opportunities from superradiant undulator sources, Journal of Physics D: Applied Physics, in press (2018)\u0000[4] Hou-Tong Chen et al., Terahertz Science and Technology 1, 42 (2008)\u0000[5] D. Polley, et al. Journal of Physics D: Applied Physics 51, 084001 (2018)\u0000[6] M. Pancaldi et al. Optics Letters 26, 2917 (2018)","PeriodicalId":247740,"journal":{"name":"Terahertz Emitters, Receivers, and Applications IX","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129280755","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}

引用次数: 0