12 research outputs found
Enhanced transmission band in periodic media with loss modulation
Copyright (2014) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
The following article appeared in: Applied Physics Letters 105, 204104 (2014); doi: 10.1063/1.4902387 and may be found at: http://dx.doi.org/10.1063/1.490238.We study the propagation of waves in a periodic array of absorbing layers. We report an anomalous increase of wave transmission through the structure related to a decrease of the absorption around the Bragg frequencies. The effect is first discussed in terms of a generic coupled wave model extended to include losses, and its predictions can be applied to different types of waves propagating in media with periodic modulation of the losses at the wavelength scale. The particular case of sound waves in an array of porous layers embedded in air is considered. An experiment designed to test the predictions demonstrates the existence of the enhanced transmission band. (C) 2014 AIP Publishing LLC.The work was supported by Spanish Ministry of Science and Innovation and European Union FEDER through Projects FIS2011-29731-C02-01 and -02, also MAT2009-09438. A.M.Y. would like to thank the Erasmus Mundus Project (WELCOME program) for supporting him. V.R.G. acknowledges financial support from the "Pays-de-la-Loire" through the post-doctoral program.Cebrecos Ruiz, A.; Picó Vila, R.; Romero García, V.; Yasser, AM.; Maigyte, L.; Herrero, R.; Botey, M.... (2014). Enhanced transmission band in periodic media with loss modulation. Applied Physics Letters. 105(20):204104-1-204104-4. doi:10.1063/1.4902387S204104-1204104-410520Figotin, A., & Vitebskiy, I. (2008). Absorption suppression in photonic crystals. Physical Review B, 77(10). doi:10.1103/physrevb.77.104421Figotin, A., & Vitebskiy, I. (2010). Magnetic Faraday rotation in lossy photonic structures. Waves in Random and Complex Media, 20(2), 298-318. doi:10.1080/17455030.2010.482575Erokhin, S. G., Lisyansky, A. A., Merzlikin, A. M., Vinogradov, A. P., & Granovsky, A. B. (2008). Photonic crystals built on contrast in attenuation. Physical Review B, 77(23). doi:10.1103/physrevb.77.233102Kumar, N., Botey, M., Herrero, R., Loiko, Y., & Staliunas, K. (2012). High-directional wave propagation in periodic loss modulated materials. Photonics and Nanostructures - Fundamentals and Applications, 10(4), 644-650. doi:10.1016/j.photonics.2012.06.003Staliunas, K., Herrero, R., & Vilaseca, R. (2009). Subdiffraction and spatial filtering due to periodic spatial modulation of the gain-loss profile. Physical Review A, 80(1). doi:10.1103/physreva.80.013821Kumar, N., Herrero, R., Botey, M., & Staliunas, K. (2013). Flat lensing by periodic loss-modulated materials. Journal of the Optical Society of America B, 30(10), 2684. doi:10.1364/josab.30.002684Psarobas, I. E. (2001). Viscoelastic response of sonic band-gap materials. Physical Review B, 64(1). doi:10.1103/physrevb.64.012303Lee, C.-Y., Leamy, M. J., & Nadler, J. H. (2010). Frequency band structure and absorption predictions for multi-periodic acoustic composites. Journal of Sound and Vibration, 329(10), 1809-1822. doi:10.1016/j.jsv.2009.11.030Laude, V., Escalante, J. M., & Martínez, A. (2013). Effect of loss on the dispersion relation of photonic and phononic crystals. Physical Review B, 88(22). doi:10.1103/physrevb.88.224302Hwan Oh, J., Jae Kim, Y., & Young Kim, Y. (2013). Wave attenuation and dissipation mechanisms in viscoelastic phononic crystals. Journal of Applied Physics, 113(10), 106101. doi:10.1063/1.4795285Hussein, M. I. (2009). Theory of damped Bloch waves in elastic media. Physical Review B, 80(21). doi:10.1103/physrevb.80.212301Andreassen, E., & Jensen, J. S. (2013). Analysis of Phononic Bandgap Structures With Dissipation. Journal of Vibration and Acoustics, 135(4). doi:10.1115/1.4023901Allard, J. F., & Atalla, N. (2009). Propagation of Sound in Porous Media. doi:10.1002/9780470747339Tournat, V., Pagneux, V., Lafarge, D., & Jaouen, L. (2004). Multiple scattering of acoustic waves and porous absorbing media. Physical Review E, 70(2). doi:10.1103/physreve.70.026609Umnova, O., Attenborough, K., & Linton, C. M. (2006). Effects of porous covering on sound attenuation by periodic arrays of cylinders. The Journal of the Acoustical Society of America, 119(1), 278-284. doi:10.1121/1.2133715Romero-García, V., Sánchez-Pérez, J. V., & Garcia-Raffi, L. M. (2010). Evanescent modes in sonic crystals: Complex dispersion relation and supercell approximation. Journal of Applied Physics, 108(4), 044907. doi:10.1063/1.3466988Christensen, J., Romero-García, V., Picó, R., Cebrecos, A., de Abajo, F. J. G., Mortensen, N. A., … Sánchez-Morcillo, V. J. (2014). Extraordinary absorption of sound in porous lamella-crystals. Scientific Reports, 4(1). doi:10.1038/srep04674Kogelnik, H., & Shank, C. V. (1972). Coupled‐Wave Theory of Distributed Feedback Lasers. Journal of Applied Physics, 43(5), 2327-2335. doi:10.1063/1.166149
Enhanced sensing and conversion of ultrasonic Rayleigh waves by elastic metasurfaces
Recent years have heralded the introduction of metasurfaces that advantageously combine the vision of sub-wavelength wave manipulation, with the design, fabrication and size advantages associated with surface excitation. An important topic within metasurfaces is the tailored rainbow trapping and selective spatial frequency separation of electromagnetic and acoustic waves using graded metasurfaces. This frequency dependent trapping and spatial frequency segregation has implications for energy concentrators and associated energy harvesting, sensing and wave filtering techniques. Different demonstrations of acoustic and electromagnetic rainbow devices have been performed, however not for deep elastic substrates that support both shear and compressional waves, together with surface Rayleigh waves; these allow not only for Rayleigh wave rainbow effects to exist but also for mode conversion from surface into shear waves. Here we demonstrate experimentally not only elastic Rayleigh wave rainbow trapping, by taking advantage of a stop-band for surface waves, but also selective mode conversion of surface Rayleigh waves to shear waves. These experiments performed at ultrasonic frequencies, in the range of 400–600 kHz, are complemented by time domain numerical simulations. The metasurfaces we design are not limited to guided ultrasonic waves and are a general phenomenon in elastic waves that can be translated across scales
Collimation and imaging behind a woodpile photonic crystal
We investigate different linear effects that appear in the light beam propagation behind a three-dimensional woodpile photonic crystal. On one hand we report and analyse experimental observation of narrow and well collimated laser beam formation behind the photonic crystal. We show that this collimation depends on the input laser beam focusing conditions. On the other hand we also report the first theoretical and numerical observation double imaging formation behind the photonic crystal. That conclusion comes from the idea that the spatial dispersion possess multiple branches (Bloch branches), generally of different curvatures, for a fixed frequency
Formation of collimated beams behind the woodpile photonic crystal
We experimentally observe formation of narrow laser beams behind the woodpile photonic crystal, when the beam remains well collimated in free propagation behind the crystal. We show that the collimation depends on the input laser beam's focusing conditions, and we interpret theoretically the observed effect by calculating the spatial dispersion of propagation eigenmodes and by numerical simulation of paraxial propagation model
Laser polymerization of photonic crystals for collimation of beams at visible wavelengths
Three-dimensional photonic crystals with woodpile structure are demonstrated to exhibit collimation of light beams behind the photonic structure. Woodpile structure photonic crystals with longitudinal modulation periods in a range of 7.4 - 7.8 μm, and transverse periods of 1 μm were fabricated using laser multi-photon polymerization technique in a negative-tone photoresist. As expected from theoretical predictions, the beams propagating along the axis of period variation collimate behind the crystal, which is a first experimental observation of the phenomenon