Measuring the Transmission Matrix in Optics: An Approach to the Study and Control of Light Propagation in Disordered Media

Author(s): S. M. Popoff, G. Lerosey, R. Carminati, M. Fink, A. C. Boccara, S. Gigan

Abstract:

“We introduce a method to experimentally measure the monochromatic transmission matrix of a complex medium in optics. This method is based on a spatial phase modulator together with a full-field interferometric measurement on a camera. We determine the transmission matrix of a thick random scattering sample. We show that this matrix exhibits statistical properties in good agreement with random matrix theory and allows light focusing and imaging through the random medium. This method might give important insight into the mesoscopic properties of a complex medium.”

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Publication: Physical Review Letters (subscription required)

Issue/Year/DOI: Phys. Rev. Lett., Volume 104, Issue 10, 100601 (2010)
DOI:10.1103/PhysRevLett.104.100601

Individually controlled multi-focus laser processing for two-photon polymerization

Author(s): Kotaro Obata, Jürgen Koch, and Boris N. Chichkov

Abstract:

“A parallel processing of two-photon polymerization structuring is demonstrated with spatial light modulator. Spatial light modulator generates multi-focus spots on the sample surface via phase modulation technique controlled by computer generated hologram pattern. Each focus spot can be individually controlled in position and laser intensity with computer generated hologram pattern displayed on spatial light modulator. The multi-focus spots two-photon polymerization achieves the fabrication of asymmetric structure. Moreover, smooth sine curved polymerized line with amplitude of 5 μm and a period of 200 μm was obtained by fast switching of CGH pattern.”

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Publication: SPIE Proceedings / Volume 7584 / Nonlinear Processing, (subscription required)

Issue/Year/DOI: Proc. SPIE 7584, 75840L (2010)
doi:10.1117/12.842117

Nonspherical laser-induced cavitation bubbles

Author(s): Kang Yuan Lim, Pedro A. Quinto-Su, Evert Klaseboer, Boo Cheong Khoo, Vasan Venugopalan, Claus-Dieter Ohl

Abstract:

“The generation of arbitrarily shaped nonspherical laser-induced cavitation bubbles is demonstrated with a optical technique. The nonspherical bubbles are formed using laser intensity patterns shaped by a spatial light modulator using linear absorption inside a liquid gap with a thickness of 40 μm. In particular we demonstrate the dynamics of elliptic, toroidal, square, and V-shaped bubbles. The bubble dynamics is recorded with a high-speed camera at framing rates of up to 300 000 frames per second. The observed bubble evolution is compared to predictions from an axisymmetric boundary element simulation which provides good qualitative agreement. Interesting dynamic features that are observed in both the experiment and simulation include the inversion of the major and minor axis for elliptical bubbles, the rotation of the shape for square bubbles, and the formation of a unidirectional jet for V-shaped bubbles. Further we demonstrate that specific bubble shapes can either be formed directly through the intensity distribution of a single laser focus, or indirectly using secondary bubbles that either confine the central bubble or coalesce with the main bubble. The former approach provides the ability to generate in principle any complex bubble geometry.”

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Publication: Physical Review E, (subscription required)

Issue/Year/DOI: Phys. Rev. E, Volume 81, Issue 1, 016308 (2010)
DOI:10.1103/PhysRevE.81.016308

Generating superpositions of higher–order Bessel beams

Author(s): Ruslan Vasilyeu, Angela Dudley, Nikolai Khilo, Andrew Forbes

Abstract:

“We report the first experimental generation of the superposition of higher-order Bessel beams, by means of a spatial light modulator (SLM) and a ring slit aperture. We present illuminating a ring slit aperture with light which has an azimuthal phase dependence, such that the field produced is a superposition of two or more higher-order Bessel beams. The experimentally produced fields are in good agreement with those calculated theoretically. The significance of these fields is that even though one is able to generate fields which carry zero orbital angular momentum, a rotation in the field’s intensity profile as it propagates is observed.”

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Publication: Optics Express (free download)

Issue/Year/DOI: Optics Express, Vol. 17, Issue 26, pp. 23389-23395 (2009)
doi:10.1364/OE.17.023389

Programmable ultrashort-pulsed flying images

Author(s): M. Bock, S. K. Das, and R. Grunwald

Abstract:

“We report the generation of programmable two-dimensional arrangements of ultrashort-pulsed fringe-less Bessel-like beams of extended depth of focus (referred to as needle beams) without truncating apertures. A sub-20-fs Ti:sapphire laser and a liquid-crystal-on-silicon spatial light modulator (LCoS-SLM) of high-fidelity temporal transfer in phase-only operation mode were used in the experiments. Axicon profiles with ultrasmall conical angles were approximated by adapted gray scale distributions. It was demonstrated that digitized image information encoded in amplitudephase maps of the needle beams is propagated over considerably large distances at minimal cross talk without the need for additional relay optics. This experiment represents a physical realization of Saari’s proposal of spatio-temporally nondiffracting “flying images” on a few-femtosecond time scale. ”

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Publication: Optics Express (free download)

Issue/Year/DOI: Optics Express, Vol. 17, Issue 9, pp. 7465-7478
doi:10.1364/OE.17.007465

Fast parallel diffractive multi-beam femtosecond laser surface micro-structuring

Author(s): Zheng Kuang, Dun Liu, Walter Perrie, Stuart Edwardson, Martin Sharp, Eamonn Fearon, Geoff Dearden, Ken Watkins

Abstract:

“Fast parallel femtosecond laser surface micro-structuring is demonstrated using a spatial light modulator (SLM). The Gratings and Lenses algorithm, which is simple and computationally fast, is used to calculate computer generated holograms (CGHs) producing diffractive multiple beams for the parallel processing. The results show that the finite laser bandwidth can significantly alter the intensity distribution of diffracted beams at higher angles resulting in elongated hole shapes. In addition, by synchronisation of applied CGHs and the scanning system, true 3D micro-structures are created on Ti6Al4V.”

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Publication: Applied Surface Science – viaScienceDirect.com (subscription required)

Issue/Year/DOI: Applied Surface Science, Volume 255, Issues 13-14, 15 April 2009, Pages 6582-6588
doi:10.1016/j.apsusc.2009.02.043

Collisions of Dark Solitons in Elongated Bose-Einstein Condensates

Author(s): S. Stellmer, C. Becker, P. Soltan-Panahi, E.-M. Richter, S. Dörscher, M. Baumert, J. Kronjäger, K. Bongs, and K. Sengstock

Abstract:

“We present experimental data showing the head-on collision of dark solitons generated in an elongated Bose-Einstein condensate. No discernable interaction can be recorded, in full agreement with the fundamental theoretical concepts of solitons as mutually transparent quasiparticles. Our soliton generation technique allows for the creation of solitons with different depths; hence, they can be distinguished and their trajectories be followed. Simulations of the 1D-Gross-Pitaevskii equation have been performed to compare the experiment with a mean-field description.”

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Publication: Physical Review Letters, (subscription required)

Issue/Year/DOI: Phys. Rev. Lett. 101, Issue 12, 120406 (2008)
doi:10.1103/PhysRevLett.101.120406

Universal Optimal Transmission of Light Through Disordered Materials

Author(s): I. M. Vellekoop and A. P. Mosk

Abstract:

“We experimentally demonstrate increased diffuse transmission of light through strongly scattering materials. Wave front shaping is used to selectively couple light to the open transport eigenchannels, specific solutions of Maxwell’s equations which the sample transmits fully, resulting in an increase of up to 44% in the total angle-integrated transmission compared to the case where plane waves are incident. The results for each of several hundreds of experimental runs are in excellent quantitative agreement with random matrix theory. From our measurements we conclude that with perfectly shaped wave fronts the transmission of a disordered sample tends to a universal value of 2/3, regardless of the thickness.”

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Publication: Physical Review Letters (subscription required)

Issue/Year/DOI: Phys. Rev. Lett., Volume 101, Issue 12, 120601 (2008)
DOI:10.1103/PhysRevLett.101.120601

Femtosecond pulse shaping in two dimensions: Towards higher complexity optical waveforms

Author(s): V. R. Supradeepa, Chen-Bin Huang, Daniel E. Leaird, Andrew M. Weiner

Abstract:

“We demonstrate a new Fourier pulse shaping apparatus capable of achieving simultaneous high resolution and broad bandwidth operation by dispersing frequency components in a two dimensional geometry through simultaneous use of a high resolution and a broad bandwidth spectral disperser. We show experimental results which demonstrate significant improvements in achievable waveform complexity (number of controllable temporal/spectral features). We also demonstrate experiments of line-by-line pulse shaping with optical frequency combs. In this regime our configuration would allow significant enhancement of the number of controllable spectral lines which may further enhance recently demonstrated massively parallel approaches to spectroscopic sensing using frequency combs.”

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Publication: Optics Express, (free download)

Issue/Year/DOI: Optics Express, Vol. 16, Issue 16, pp. 11878-11887 (2008)
doi:10.1364/OE.16.011878

Power amplification of a phased array steered laser beam

Author(s): C.A. SchäferCorresponding, O. Matoba, N. Kaya

Abstract:

“Steering a laser beam by an optical phased array provides non-mechanical beam steering, high angular resolution with large apertures. It is therefore considered in several applications such as laser communication and power transmission links between moving objects. However, in many devices the incident power density is limited and the fill factor leads to a high loss of light. These two drawbacks can be overcome by an amplification of the steered beam.

In this paper, we study amplification by a two wave mixing process. The steered beam gets amplified by energy transfer from a pump beam inside a nonlinear medium. By building a telescope setup, the medium can be placed at different positions leading to different characteristics of the amplification process.

We examine amplification in the image and Fourier plane. Then we also propose the Fresnel region as a compromise between the two extremes for the place of the amplification process.”

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Publication: Acta Astronautica – via ScienceDirect.com (subscription required)

Issue/Year/DOI: Acta Astronautica, Volume 63, Issues 1-4, July-August 2008, Pages 334-341
doi:10.1016/j.actaastro.2007.12.052