Role of edge inclination in optical microdisk resonator for label-free sensing

In this paper we report on the measurement and modelling of enhanced optical refractometric sensors based on whispering-gallery-modes. The devices under test are optical microresonators made of silicon nitride on silicon oxide. In our approach, these microresonators are vertically coupled to a buried waveguide with the aim of creating integrated and cost-effective devices. The optimization analysis is a delicate balance of resonance quality factor and evanescent field overlap with the sorrounding environment to analyze. By numerical simulations we show that the microdisk thickness is critical to yield high figure of merit for the sensor, while edge inclination is less important. We also show that figures of merit as high as 1600/RIU are feasible.Comment: 10 page

Thermal Emission of Silicon at Near-Infrared Frequencies Mediated by Mie Resonances

[EN] Planck's law constitutes one of the cornerstones in physics. It explains the well-known spectrum of an ideal blackbody consisting of a smooth curve, whose peak wavelength and intensity depend on the temperature of the body. This scenario changes drastically, however, when the size of the emitting object is comparable to the wavelength of the emitted radiation. Here we show that a silicon microsphere (2-3 mu m in diameter) heated to around 800 degrees C yields a thermal emission spectrum consisting of pronounced peaks that are associated with Mie resonances. We experimentally demonstrate in the near-infrared the existence of modes with an ultrahigh quality factor, Q, of 400, which is substantially higher than values reported so far, and set a new benchmark in the field of thermal emission. Simulations predict that the thermal response of the microspheres is very fast, about 15 mu s. Additionally, the possibility of achieving light emission above the Planck limit at some frequency ranges is envisaged.This work was supported by several projects of the Spanish Ministry of Economy and Competitiveness (MINECO), Severo Ochoa program for Centers of Excellence (SEV-2016-0683), MAT2015-69669-PM, ENE2013-49984-EXP, ENE2015-74009-JIN (cofunded by the European Regional Development Fund), and of the Spanish Science, Innovation and Universities, PGC2018-099744-B-100. F.R.-M. thanks the financial contribution of MINECO through the program for young researchers support, TEC 2015 2015-74405-JIN. The authors greatly acknowledge the contribution of Prof. Francisco Meseguer for both the fruitful discussions and the revision of the manuscript, and Prof. Marie Louise McCarrey for careful proofreading of the manuscript.Fenollosa Esteve, R.; Ramiro-Manzano, F.; Garín Escrivá, M.; Alcubilla, R. (2019). Thermal Emission of Silicon at Near-Infrared Frequencies Mediated by Mie Resonances. ACS Photonics. 6(12):3174-3179. https://doi.org/10.1021/acsphotonics.9b01513S3174317961

Chaotic dynamics in coupled resonator sequences

Optically induced thermal and free carrier nonlinearities in silicon micro-ring resonator influence their behavior. They can be either deleterious by making them instable and by driving their resonances out of the designed wavelengths, or enabler of different applications. Among the most interesting one, there are optical bistability and self induced oscillations. These lead to all optical logic, signal modulation, optical memories and applications in neural networks. Here, we theoretically and experimentally demonstrate that when many resonators are coupled together, thermal and free carrier nonlinearities induce also chaos. The chaotic dynamics are deeply analyzed using experimentally reconstructed phase space trajectories and the tool of Lyapunov exponents

Unidirectional reflection from an integrated 'taiji' microresonator

We study light transmission and reflection from an integrated microresonator device, formed by a circular microresonator coupled to a bus waveguide, with an embedded S-shaped additional crossover waveguide element that selectively couples counter-propagating modes in a propagation-direction-dependent way. The overall shape of the device resembles a 'taiji' symbol, hence its name. While Lorentz reciprocity is preserved in transmission, the peculiar geometry allows us to exploit the non-Hermitian nature of the system to obtain high-contrast unidirectional reflection with negligible reflection for light incident in one direction and a significant reflection in the opposite direction

Groove-assisted solution growth of lead bromide perovskite aligned nanowires: a simple method towards photoluminescent materials with guiding light properties

[EN] High refractive index nanowires are very attractive because of their waveguiding properties and their multiple applications. In this sense, metal halide perovskites, an emerging and appealing optoelectronic material, have also been tailored into nanowire structures. Here, we present an easy, low-cost and versatile method that has made possible to achieve nanowires of controlled and uniform width. The method has been applied here to all-inorganic and hybrid lead bromide perovskite (CsPbBr3 and CH3NH3PbBr3 respectively) materials. The procedure is based on the spin coating of precursor solutions, at room temperature, on a PDMS replica of the periodic grooves and lands of commercially available Compact Disc (CD) or Digital Versatile Disc (DVD) polycarbonate plates. The method can be applied for the synthesis of other material nanowires before being transferred onto other substrates. The obtained CsPbBr3 and CH3NH3PbBr3 nanowires exhibit high photoluminescence and guiding light properties along the material.The authors would like to gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness (MIMECO) (Severo Ochoa (SEV-2016-0683), MAT2015-69669-P projects) and Generalitat Valenciana (Prometeo II/2017/026 Excellency project). P. A. acknowledges the Fundacion Ramon Areces (XVII Concurso Nacional para la adjudicacion de Ayudas a la Investigacion en Ciencias de la Vida y de la Materia) for its funding. F. R.-M. thanks the financial contribution of the Spanish Ministry of Economy and Competitiveness (MIMECO) through the program for young researchers support (TEC 2015 2015-74405-JIN). Finally, IR also thanks the Electron Microscopy Service of the Universitat Politecnica de Valencia for their support in FESEM image acquisition and FIB milling, as well as Ana Moreno for her help in template preparation.Rodriguez, I.; Fenollosa Esteve, R.; Ramiro Manzano, F.; García-Aboal, R.; Atienzar Corvillo, PE.; Meseguer Rico, FJ. (2019). Groove-assisted solution growth of lead bromide perovskite aligned nanowires: a simple method towards photoluminescent materials with guiding light properties. Materials Chemistry Frontiers. 3(9):1754-1760. https://doi.org/10.1039/c9qm00210cS1754176039Semiconductor nanowires: From next-generation Electronics to Sustainable Energy , ed. W. Lu and J. Xiang , RSC Smart Materials Series, 2015Semiconductor Nanowires, Materials, Synthesis, Characterization and Applications , ed. J. Arbiol and Q. Xiong , Woodhead Publishing , 2015Peng, K.-Q., Wang, X., Li, L., Hu, Y., & Lee, S.-T. (2013). Silicon nanowires for advanced energy conversion and storage. Nano Today, 8(1), 75-97. doi:10.1016/j.nantod.2012.12.009M. Mikolajick and W. M.Weber , Silicon Nanowires in Anisotropic Nanomaterials , ed. Q. Li , Springer , 2015 , pp. 1–25Hasan, M., Huq, M. F., & Mahmood, Z. H. (2013). A review on electronic and optical properties of silicon nanowire and its different growth techniques. SpringerPlus, 2(1). doi:10.1186/2193-1801-2-151Liu, Z., Mi, Y., Guan, X., Su, Z., Liu, X., & Wu, T. (2018). Morphology-Tailored Halide Perovskite Platelets and Wires: From Synthesis, Properties to Optoelectronic Devices. Advanced Optical Materials, 6(17), 1800413. doi:10.1002/adom.201800413Fu, Y., Zhu, H., Chen, J., Hautzinger, M. P., Zhu, X.-Y., & Jin, S. (2019). Metal halide perovskite nanostructures for optoelectronic applications and the study of physical properties. Nature Reviews Materials, 4(3), 169-188. doi:10.1038/s41578-019-0080-9Manser, J. S., Christians, J. A., & Kamat, P. V. (2016). Intriguing Optoelectronic Properties of Metal Halide Perovskites. Chemical Reviews, 116(21), 12956-13008. doi:10.1021/acs.chemrev.6b00136Kitazawa, N., Watanabe, Y., & Nakamura, Y. (2002). Journal of Materials Science, 37(17), 3585-3587. doi:10.1023/a:1016584519829Albero, J., & García, H. (2017). Luminescence control in hybrid perovskites and their applications. Journal of Materials Chemistry C, 5(17), 4098-4110. doi:10.1039/c7tc00714kLongo, G., La-Placa, M.-G., Sessolo, M., & Bolink, H. J. (2017). High Photoluminescence Quantum Yields in Organic Semiconductor-Perovskite Composite Thin Films. ChemSusChem, 10(19), 3788-3793. doi:10.1002/cssc.201701265Richter, J. M., Abdi-Jalebi, M., Sadhanala, A., Tabachnyk, M., Rivett, J. P. H., Pazos-Outón, L. M., … Friend, R. H. (2016). Enhancing photoluminescence yields in lead halide perovskites by photon recycling and light out-coupling. Nature Communications, 7(1). doi:10.1038/ncomms13941De Wolf, S., Holovsky, J., Moon, S.-J., Löper, P., Niesen, B., Ledinsky, M., … Ballif, C. (2014). Organometallic Halide Perovskites: Sharp Optical Absorption Edge and Its Relation to Photovoltaic Performance. The Journal of Physical Chemistry Letters, 5(6), 1035-1039. doi:10.1021/jz500279bWehrenfennig, C., Eperon, G. E., Johnston, M. B., Snaith, H. J., & Herz, L. M. (2013). High Charge Carrier Mobilities and Lifetimes in Organolead Trihalide Perovskites. Advanced Materials, 26(10), 1584-1589. doi:10.1002/adma.201305172Sutherland, B. R., & Sargent, E. H. (2016). Perovskite photonic sources. Nature Photonics, 10(5), 295-302. doi:10.1038/nphoton.2016.62Bi, D., Tress, W., Dar, M. I., Gao, P., Luo, J., Renevier, C., … Hagfeldt, A. (2016). Efficient luminescent solar cells based on tailored mixed-cation perovskites. Science Advances, 2(1). doi:10.1126/sciadv.1501170Jung, H. S., & Park, N.-G. (2014). Perovskite Solar Cells: From Materials to Devices. Small, 11(1), 10-25. doi:10.1002/smll.201402767Zhang, W., Eperon, G. E., & Snaith, H. J. (2016). Metal halide perovskites for energy applications. Nature Energy, 1(6). doi:10.1038/nenergy.2016.48Kim, Y.-H., Wolf, C., Kim, Y.-T., Cho, H., Kwon, W., Do, S., … Lee, T.-W. (2017). Highly Efficient Light-Emitting Diodes of Colloidal Metal–Halide Perovskite Nanocrystals beyond Quantum Size. ACS Nano, 11(7), 6586-6593. doi:10.1021/acsnano.6b07617Veldhuis, S. A., Boix, P. P., Yantara, N., Li, M., Sum, T. C., Mathews, N., & Mhaisalkar, S. G. (2016). Perovskite Materials for Light-Emitting Diodes and Lasers. Advanced Materials, 28(32), 6804-6834. doi:10.1002/adma.201600669Wang, N., Cheng, L., Ge, R., Zhang, S., Miao, Y., Zou, W., … Huang, W. (2016). Perovskite light-emitting diodes based on solution-processed self-organized multiple quantum wells. Nature Photonics, 10(11), 699-704. doi:10.1038/nphoton.2016.185Zhu, H., Fu, Y., Meng, F., Wu, X., Gong, Z., Ding, Q., … Zhu, X.-Y. (2015). Lead halide perovskite nanowire lasers with low lasing thresholds and high quality factors. Nature Materials, 14(6), 636-642. doi:10.1038/nmat4271Harwell, J. R., Whitworth, G. L., Turnbull, G. A., & Samuel, I. D. W. (2017). Green Perovskite Distributed Feedback Lasers. Scientific Reports, 7(1). doi:10.1038/s41598-017-11569-3Jia, Y., Kerner, R. A., Grede, A. J., Rand, B. P., & Giebink, N. C. (2017). Continuous-wave lasing in an organic–inorganic lead halide perovskite semiconductor. Nature Photonics, 11(12), 784-788. doi:10.1038/s41566-017-0047-6Xing, G., Mathews, N., Lim, S. S., Yantara, N., Liu, X., Sabba, D., … Sum, T. C. (2014). Low-temperature solution-processed wavelength-tunable perovskites for lasing. Nature Materials, 13(5), 476-480. doi:10.1038/nmat3911Zhang, S., Audebert, P., Wei, Y., Al Choueiry, A., Lanty, G., Bréhier, A., … Deleporte, E. (2010). Preparations and Characterizations of Luminescent Two Dimensional Organic-inorganic Perovskite Semiconductors. Materials, 3(5), 3385-3406. doi:10.3390/ma3053385Shoaib, M., Zhang, X., Wang, X., Zhou, H., Xu, T., Wang, X., … Pan, A. (2017). Directional Growth of Ultralong CsPbBr3 Perovskite Nanowires for High-Performance Photodetectors. Journal of the American Chemical Society, 139(44), 15592-15595. doi:10.1021/jacs.7b08818Xing, J., Liu, X. F., Zhang, Q., Ha, S. T., Yuan, Y. W., Shen, C., … Xiong, Q. (2015). Vapor Phase Synthesis of Organometal Halide Perovskite Nanowires for Tunable Room-Temperature Nanolasers. Nano Letters, 15(7), 4571-4577. doi:10.1021/acs.nanolett.5b01166Gu, L., Tavakoli, M. M., Zhang, D., Zhang, Q., Waleed, A., Xiao, Y., … Fan, Z. (2016). 3D Arrays of 1024-Pixel Image Sensors based on Lead Halide Perovskite Nanowires. Advanced Materials, 28(44), 9713-9721. doi:10.1002/adma.201601603Wang, Y., Sun, X., Shivanna, R., Yang, Y., Chen, Z., Guo, Y., … Shi, J. (2016). Photon Transport in One-Dimensional Incommensurately Epitaxial CsPbX3 Arrays. Nano Letters, 16(12), 7974-7981. doi:10.1021/acs.nanolett.6b04297Park, K., Lee, J. W., Kim, J. D., Han, N. S., Jang, D. M., Jeong, S., … Song, J. K. (2016). Light–Matter Interactions in Cesium Lead Halide Perovskite Nanowire Lasers. The Journal of Physical Chemistry Letters, 7(18), 3703-3710. doi:10.1021/acs.jpclett.6b01821Chen, J., Fu, Y., Samad, L., Dang, L., Zhao, Y., Shen, S., … Jin, S. (2016). Vapor-Phase Epitaxial Growth of Aligned Nanowire Networks of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I). Nano Letters, 17(1), 460-466. doi:10.1021/acs.nanolett.6b04450Zhou, H., Yuan, S., Wang, X., Xu, T., Wang, X., Li, H., … Pan, A. (2016). Vapor Growth and Tunable Lasing of Band Gap Engineered Cesium Lead Halide Perovskite Micro/Nanorods with Triangular Cross Section. ACS Nano, 11(2), 1189-1195. doi:10.1021/acsnano.6b07374Wang, X., Zhou, H., Yuan, S., Zheng, W., Jiang, Y., Zhuang, X., … Pan, A. (2017). Cesium lead halide perovskite triangular nanorods as high-gain medium and effective cavities for multiphoton-pumped lasing. Nano Research, 10(10), 3385-3395. doi:10.1007/s12274-017-1551-1Oksenberg, E., Sanders, E., Popovitz-Biro, R., Houben, L., & Joselevich, E. (2017). Surface-Guided CsPbBr3 Perovskite Nanowires on Flat and Faceted Sapphire with Size-Dependent Photoluminescence and Fast Photoconductive Response. Nano Letters, 18(1), 424-433. doi:10.1021/acs.nanolett.7b04310Chen, J., Luo, Z., Fu, Y., Wang, X., Czech, K. J., Shen, S., … Jin, S. (2019). Tin(IV)-Tolerant Vapor-Phase Growth and Photophysical Properties of Aligned Cesium Tin Halide Perovskite (CsSnX3; X = Br, I) Nanowires. ACS Energy Letters, 4(5), 1045-1052. doi:10.1021/acsenergylett.9b00543Eaton, S. W., Lai, M., Gibson, N. A., Wong, A. B., Dou, L., Ma, J., … Yang, P. (2016). Lasing in robust cesium lead halide perovskite nanowires. Proceedings of the National Academy of Sciences, 113(8), 1993-1998. doi:10.1073/pnas.1600789113Tavakoli, M. M., Waleed, A., Gu, L., Zhang, D., Tavakoli, R., Lei, B., … Fan, Z. (2017). A non-catalytic vapor growth regime for organohalide perovskite nanowires using anodic aluminum oxide templates. Nanoscale, 9(18), 5828-5834. doi:10.1039/c7nr00444cIm, J.-H., Luo, J., Franckevičius, M., Pellet, N., Gao, P., Moehl, T., … Park, N.-G. (2015). Nanowire Perovskite Solar Cell. Nano Letters, 15(3), 2120-2126. doi:10.1021/acs.nanolett.5b00046Wong, A. B., Lai, M., Eaton, S. W., Yu, Y., Lin, E., Dou, L., … Yang, P. (2015). Growth and Anion Exchange Conversion of CH3NH3PbX3 Nanorod Arrays for Light-Emitting Diodes. Nano Letters, 15(8), 5519-5524. doi:10.1021/acs.nanolett.5b02082Deng, H., Dong, D., Qiao, K., Bu, L., Li, B., Yang, D., … Song, H. (2015). Growth, patterning and alignment of organolead iodide perovskite nanowires for optoelectronic devices. Nanoscale, 7(9), 4163-4170. doi:10.1039/c4nr06982jSpina, M., Bonvin, E., Sienkiewicz, A., Náfrádi, B., Forró, L., & Horváth, E. (2016). Controlled growth of CH3NH3PbI3 nanowires in arrays of open nanofluidic channels. Scientific Reports, 6(1). doi:10.1038/srep19834Ashley, M. J., O’Brien, M. N., Hedderick, K. R., Mason, J. A., Ross, M. B., & Mirkin, C. A. (2016). Templated Synthesis of Uniform Perovskite Nanowire Arrays. Journal of the American Chemical Society, 138(32), 10096-10099. doi:10.1021/jacs.6b05901Deng, W., Huang, L., Xu, X., Zhang, X., Jin, X., Lee, S.-T., & Jie, J. (2017). Ultrahigh-Responsivity Photodetectors from Perovskite Nanowire Arrays for Sequentially Tunable Spectral Measurement. Nano Letters, 17(4), 2482-2489. doi:10.1021/acs.nanolett.7b00166Wang, S., Wang, K., Gu, Z., Wang, Y., Huang, C., Yi, N., … Song, Q. (2017). Solution-Phase Synthesis of Cesium Lead Halide Perovskite Microrods for High-Quality Microlasers and Photodetectors. Advanced Optical Materials, 5(11), 1700023. doi:10.1002/adom.201700023Petrov, A. A., Pellet, N., Seo, J.-Y., Belich, N. A., Kovalev, D. Y., Shevelkov, A. V., … Graetzel, M. (2016). New Insight into the Formation of Hybrid Perovskite Nanowires via Structure Directing Adducts. Chemistry of Materials, 29(2), 587-594. doi:10.1021/acs.chemmater.6b03965Fu, Y., Zhu, H., Stoumpos, C. C., Ding, Q., Wang, J., Kanatzidis, M. G., … Jin, S. (2016). Broad Wavelength Tunable Robust Lasing from Single-Crystal Nanowires of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I). ACS Nano, 10(8), 7963-7972. doi:10.1021/acsnano.6b03916Zhang, D., Eaton, S. W., Yu, Y., Dou, L., & Yang, P. (2015). Solution-Phase Synthesis of Cesium Lead Halide Perovskite Nanowires. Journal of the American Chemical Society, 137(29), 9230-9233. doi:10.1021/jacs.5b05404Zhang, D., Yu, Y., Bekenstein, Y., Wong, A. B., Alivisatos, A. P., & Yang, P. (2016). Ultrathin Colloidal Cesium Lead Halide Perovskite Nanowires. Journal of the American Chemical Society, 138(40), 13155-13158. doi:10.1021/jacs.6b08373Fu, Y., Zhu, H., Schrader, A. W., Liang, D., Ding, Q., Joshi, P., … Jin, S. (2016). Nanowire Lasers of Formamidinium Lead Halide Perovskites and Their Stabilized Alloys with Improved Stability. Nano Letters, 16(2), 1000-1008. doi:10.1021/acs.nanolett.5b04053Liu, P., He, X., Ren, J., Liao, Q., Yao, J., & Fu, H. (2017). Organic–Inorganic Hybrid Perovskite Nanowire Laser Arrays. ACS Nano, 11(6), 5766-5773. doi:10.1021/acsnano.7b01351Lee, M. M., Teuscher, J., Miyasaka, T., Murakami, T. N., & Snaith, H. J. (2012). Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites. Science, 338(6107), 643-647. doi:10.1126/science.1228604Niu, G., Guo, X., & Wang, L. (2015). Review of recent progress in chemical stability of perovskite solar cells. Journal of Materials Chemistry A, 3(17), 8970-8980. doi:10.1039/c4ta04994bBerhe, T. A., Su, W.-N., Chen, C.-H., Pan, C.-J., Cheng, J.-H., Chen, H.-M., … Hwang, B.-J. (2016). Organometal halide perovskite solar cells: degradation and stability. Energy & Environmental Science, 9(2), 323-356. doi:10.1039/c5ee02733kBrunetti, B., Cavallo, C., Ciccioli, A., Gigli, G., & Latini, A. (2016). On the Thermal and Thermodynamic (In)Stability of Methylammonium Lead Halide Perovskites. Scientific Reports, 6(1). doi:10.1038/srep31896Conings, B., Drijkoningen, J., Gauquelin, N., Babayigit, A., D’Haen, J., D’Olieslaeger, L., … Boyen, H.-G. (2015). Intrinsic Thermal Instability of Methylammonium Lead Trihalide Perovskite. Advanced Energy Materials, 5(15), 1500477. doi:10.1002/aenm.201500477Kulbak, M., Gupta, S., Kedem, N., Levine, I., Bendikov, T., Hodes, G., & Cahen, D. (2015). Cesium Enhances Long-Term Stability of Lead Bromide Perovskite-Based Solar Cells. The Journal of Physical Chemistry Letters, 7(1), 167-172. doi:10.1021/acs.jpclett.5b02597Saliba, M., Matsui, T., Seo, J.-Y., Domanski, K., Correa-Baena, J.-P., Nazeeruddin, M. K., … Grätzel, M. (2016). Cesium-containing triple cation perovskite solar cells: improved stability, reproducibility and high efficiency. Energy & Environmental Science, 9(6), 1989-1997. doi:10.1039/c5ee03874jService, R. F. (2016). Cesium fortifies next-generation solar cells. Science, 351(6269), 113-114. doi:10.1126/science.351.6269.113Kang, J., & Wang, L.-W. (2017). High Defect Tolerance in Lead Halide Perovskite CsPbBr3. The Journal of Physical Chemistry Letters, 8(2), 489-493. doi:10.1021/acs.jpclett.6b02800Pazos-Outón, L. M., Szumilo, M., Lamboll, R., Richter, J. M., Crespo-Quesada, M., Abdi-Jalebi, M., … Deschler, F. (2016). Photon recycling in lead iodide perovskite solar cells. Science, 351(6280), 1430-1433. doi:10.1126/science.aaf1168Dursun, I., Zheng, Y., Guo, T., De Bastiani, M., Turedi, B., Sinatra, L., … Malko, A. V. (2018). Efficient Photon Recycling and Radiation Trapping in Cesium Lead Halide Perovskite Waveguides. ACS Energy Letters, 3(7), 1492-1498. doi:10.1021/acsenergylett.8b00758F. Ramiro-Manzano , R.García-Aboal , R.Fenollosa , S.Basi , I.Rodriguez , P.Atienzar and F.Meseguer , Optical properties of organic/inorganic perovskite microcrystals through the characterization of Fabry–Pérot resonances, 2019, submittedRamiro-Manzano, F., Bonet, E., Rodriguez, I., & Meseguer, F. (2010). Colloidal Crystal Thin Films Grown into Corrugated Surface Templates. Langmuir, 26(7), 4559-4562. doi:10.1021/la904396mGarcía-Aboal, R., Fenollosa, R., Ramiro-Manzano, F., Rodríguez, I., Meseguer, F., & Atienzar, P. (2018). Single Crystal Growth of Hybrid Lead Bromide Perovskites Using a Spin-Coating Method. ACS Omega, 3(5), 5229-5236. doi:10.1021/acsomega.8b00447Fenollosa, R., Garín, M., & Meseguer, F. (2016). Spherical silicon photonic microcavities: From amorphous to polycrystalline. Physical Review B, 93(23). doi:10.1103/physrevb.93.23530

Single Crystal Growth of Hybrid Lead Bromide Perovskites Using a Spin-Coating Method

[EN] Synthesis and studies of single crystals of hybrid perovskite are important for achieving a better understanding of the optoelectronic phenomena occurring in this material and for improving ongoing applications. Here, we report on the growth of micrometer-size single crystals of methylammonium lead bromide (MAPbBr3) using the spin coating deposition method on a quartz substrate. We studied the influence of the rotation speed and the use of three different additives N-cyclohexyl-2-pyrrolidone, dimethyl sulfoxide, and 4-tert-butylpyridine on the crystal size and shape. The introduction of an additive in the precursor solution is revealed to be very useful for obtaining crystals with well-defined geometries and for decreasing the amount of defects. In this way, high-quality single crystals that sustain optical resonating modes were obtained and characterized by transmittance and photoluminescence measurements.Financial support from the Spanish Ministry of Economy and Competitiveness (Severo Ochoa, SEV-2016-0683), Intramural CSIC project 201680I006, and Fundacion Ramon Areces (XVII Concurso Nacional para la adjudicacion de Ayudas a la Investigacion en Ciencias de la Vida y de la Materia) is gratefully acknowledged. Financial support was also provided by the Spanish Ministry of Economy and Competitiveness (Mineco) of Spain (TEC2015-74405-JIN), MAT2015-69669-P, and regional government grant PrometeoII/2017/026.García-Aboal, R.; Fenollosa Esteve, R.; Ramiro Manzano, F.; Rodriguez, I.; Messeguer Rico, FJ.; Atienzar Corvillo, PE. (2018). Single Crystal Growth of Hybrid Lead Bromide Perovskites Using a Spin-Coating Method. ACS Omega. 3(5):5229-5236. https://doi.org/10.1021/acsomega.8b00447S522952363

A fully integrated high-Q Whispering-Gallery Wedge Resonator

Microresonator devices which posses ultra-high quality factors are essential for fundamental investigations and applications. Microsphere and microtoroid resonators support remarkably high Q's at optical frequencies, while planarity constrains preclude their integration into functional lightwave circuits. Conventional semiconductor processing can also be used to realize ultra-high-Q's with planar wedge-resonators. Still, their full integration with side-coupled dielectric waveguides remains an issue. Here we show the full monolithic integration of a wedge-resonator/waveguide vertically-coupled system on a silicon chip. In this approach the cavity and the waveguide lay in different planes. This permits to realize the shallow-angle wedge while the waveguide remains intact, allowing therefore to engineer a coupling of arbitrary strength between these two. The precise size-control and the robustness against post-processing operation due to its monolithic integration makes this system a prominent platform for industrial-scale integration of ultra-high-Q devices into planar lightwave chips.Comment: 6 pages, 4 figure

Optical properties of organic/inorganic perovskite microcrystals through the characterization of Fabry-Perot resonances

[EN] A precise knowledge of the optical properties, specifically the refractive index, of organic/inorganic perovskites, is essential for pushing forward the performance of the current photovoltaic devices that are being developed from these materials. Here we show a robust method for determining the real and the imaginary part of the refractive index of MAPbBr(3) thin films and micrometer size single crystals with planar geometry. The simultaneous fit of both the optical transmittance and the photoluminescence spectra to theoretical models defines unambiguously the refractive index and the crystal thickness. Because the method relies on the optical resonance phenomenon occurring in these microstructures, it can be used to further develop optical microcavities from perovskites or from other optical materials.This work was supported by the Spanish ministry of Economy, Industry and Competitiveness (MINECO) through the projects TEC2015-74405-JIN, MAT2015-69669-P as well as the regional projects of both Provincia Autonoma di Trento (PAT) of Italy, through the call Grandi Progetti 2012: SIQURO and the Comunidad Valenciana of Spain project PrometeoII/2014/026.Ramiro Manzano, F.; García-Aboal, R.; Fenollosa Esteve, R.; Biasi, S.; Rodriguez, I.; Atienzar Corvillo, PE.; Meseguer Rico, FJ. (2020). Optical properties of organic/inorganic perovskite microcrystals through the characterization of Fabry-Perot resonances. Dalton Transactions. 49(36):12798-12804. https://doi.org/10.1039/d0dt02254c1279812804493

Porous silicon microcavities: Synthesis, characterization, and application to photonic barcode devices

[EN] We have recently developed a new type of porous silicon we name as porous silicon colloids. They consist of almost perfect spherical silicon nanoparticles with a very smooth surface, able to scatter (and also trap) light very efficiently in a large-span frequency range. Porous silicon colloids have unique properties because of the following: (a) they behave as optical microcavities with a high refractive index, and (b) the intrinsic photoluminescence (PL) emission is coupled to the optical modes of the microcavity resulting in a unique luminescence spectrum profile. The PL spectrum constitutes an optical fingerprint identifying each particle, with application for biosensing. In this paper, we review the synthesis of silicon colloids for developing porous nanoparticles. We also report on the optical properties with special emphasis in the PL emission of porous silicon microcavities. Finally, we present the photonic barcode concept. © 2012 Ramiro-Manzano et al.This work has been partially supported by the Spanish CICyT projects, FIS2009-07812, Consolider CSD2007-046, and PROMETEO/2010/043.Ramiro Manzano, F.; Fenollosa Esteve, R.; Xifre Perez, E.; Garín Escrivá, M.; Meseguer Rico, FJ. (2012). Porous silicon microcavities: Synthesis, characterization, and application to photonic barcode devices. Nanoscale Research Letters. 7:497-1-497-6. https://doi.org/10.1186/1556-276X-7-497S497-1497-6

Packing confined hard spheres denser with adaptive prism phases

[EN] We show that hard spheres confined between two parallel hard plates pack denser with periodic adaptive prismatic structures which are composed of alternating prisms of spheres. The internal structure of the prisms adapts to the slit height which results in close packings for a range of plate separations, just above the distance where three intersecting square layers fit exactly between the plates. The adaptive prism phases are also observed in real-space experiments on confined sterically stabilized colloids and in Monte Carlo simulations at finite pressure. © 2012 American Physical Society.We thank Elvira Bonet, Moises Garin, and Kevin Mutch for helpful discussions. This work was partially supported by the DFG within the SFB TR6 (Project D1), and by the Spanish CICyT Projects FIS2009-07812 and PROMETEO/2010/043. F. R.-M. acknowledges the support from the EU Marie Curie Project APPCOPTOR-275150 (FP7-PEOPLE-2010-IEF).Oguz, EC.; Merechal, M.; Ramiro Manzano, F.; Rodríguez, M.; Messina, R.; Meseguer Rico, FJ.; Loewen, H. (2012). Packing confined hard spheres denser with adaptive prism phases. Physical Review Letters. 109(21):218301-1-218301-5. https://doi.org/10.1103/PhysRevLett.109.218301S218301-1218301-51092