Digital phase conjugation of second harmonic radiation emitted by nanoparticles in turbid media

Author(s): Chia-Lung Hsieh, Ye Pu, Rachel Grange, and Demetri Psaltis

Abstract:

“We demonstrate focusing coherent light on a nanoparticle through turbid media based on digital optical phase conjugation of second harmonic generation (SHG) field from the nanoparticle. A SHG active nanoparticle inside a turbid medium was excited at the fundamental frequency and emitted SHG field as a point source. The SHG emission was scattered by the turbid medium, and the scattered field was recorded by off-axis digital holography. A phase-conjugated beam was then generated by using a phase-only spatial light modulator and sent back through the turbid medium, which formed a nearly ideal focus on the nanoparticle.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 12, pp. 12283-12290 (2010)
DOI: 10.1364/OE.18.012283

Direct creation of a photoinduced metallic structure and its optical properties in the terahertz frequency region

Author(s): Takanori Okada, Kazufumi Ooi, Yosuke Nakata, Koji Fujita, Katsuhisa Tanaka, Koichiro Tanaka

Abstract:

“We investigate the surface electromagnetic characteristics of a photoinduced periodical structure using the attenuated total reflection (ATR) technique in the terahertz frequency region. A wire grating structure is generated at the surface of a silicon prism by irradiation with a spatially modulated, ultrafast pulsed laser. A characteristic minimum due to the excitation of surface waves is observed in the ATR spectrum. The depth profile of the photoinduced carrier layer is also studied. We confirm that the photoinduced structure has metallic properties. This fabrication technique will be developed as a simple method to create “active” structures.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 35, Issue 10, pp. 1719-1721 (2010)
DOI: 10.1364/OL.35.001719

Materials for an Updatable Holographic 3D Display

Author(s): Cory W. Christenson, Pierre-Alexandre Blanche, Savas Tay, Ram Voorakaranam, Tao Gu, Weiping Lin, Peng Wang, Michiharu Yamamoto, Jayan Thomas, Robert A. Norwood, and Nasser Peyghambarian

Abstract:

“Holography is a powerful technique for providing high-resolution, realistic three-dimensional (3D) images without the need for special eyewear. A material that takes full advantage of the potential of holography, including updatability, has not existed. Here, the first updatable holographic 3D display based on a photorefractive polymer is summarized. The performance characteristics of these materials are measured, and how they relate to the development of additional display enhancements such as pulsed writing, white light viewing, and large viewing angle, are discussed.”

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Publication: Journal of Display Technology
Issue/Year: Journal of Display Technology, Issue: 99, pp1-7, (2010)
DOI: 10.1109/JDT.2010.2046620

Image Transmission Through an Opaque Material

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

Abstract:

“Optical imaging relies on the ability to illuminate an object and to collect and make sense of the light it scatters or transmit. Propagation through complex media such as biological tissues was so far believed to degrade the attainable depth as well as the resolution for imaging cite{sebbah2001introduction} because of multiple scattering. This is why such media are usually considered opaque. Recent experiments have demonstrated that multiply scattered light can in fact be harnessed thanks to wavefront control, and even put to profit to surpass what one can achieve within a homogenous medium in terms of focusing. Very recently, we have proven that it is possible to measure the complex mesoscopic optical transmission channels that allow light to traverse through an opaque medium. Here we show that we can optimally exploit those channels to coherently transmit and recover with a high fidelity an arbitrary image, independently of the complexity of the propagation. Our approach gives a general framework for coherent imaging in complex media, going well beyond focusing. It is valid for any linear complex media, and could be extended to several novel photonic materials, whatever the amount of scattering or disorder (from complete disorder to weakly disordered photonic crystals, and from superdiffusive to Anderson localization). ”

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Publication:arXiv.org / physics
Issue/Year:arXiv:1005.0532 (May 2010)

Wavefront control of a multicore ytterbium-doped pulse fiber amplifier by digital holography

Author(s): Mathieu Paurisse, Marc Hanna, Frédéric Druon, and Patrick Georges

Abstract:

“We demonstrate the active wavefront control of a 19-core ytterbium-doped fiber amplifier by the digital holography technique. The output wavefront is corrected even in the presence of large externally induced perturbations, with a measured output Strehl ratio of 0.6 in all cases. The wavefront-controlled multicore fiber is used to amplify 800 ps pulses at 1064 nm at a repetition rate of 40 kHz , and a gain of 23 dB is obtained.”

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Publication: Optics Letters
Issue/Year: Optics Letters, Vol. 35, Issue 9, pp. 1428-1430 (2010)
DOI: 10.1364/OL.35.001428

Digital pre-filtering approach to improve optically reconstructed wavefields in opto-electronic holography

Author(s): Mostafa Agour, Claas Falldorf and Christoph von Kopylow

Abstract:

“We present a method that significantly improves the quality of the optically reconstructed complex amplitude from a spatial light modulator (SLM). This method is based on applying a digital pre-filtering of the SLM’s encoded distribution to compensate the signal distortion caused by the SLM’s finite pixel size. In this approach the complex transmittance is changed in such a way that it compensates the modulation in the Fourier plane. The basic principle of this technique and its experimental verification are described.”

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Publication: Journal of Optics
Issue/Year: Journal of Optics, Vol. 12, Issue 5, 055401 (2010)
DOI: 10.1088/2040-8978/12/5/055401

Phase contrast enhancement in microscopy using spiral phase filtering

Author(s): Guohai Situ, Michael Warber, Giancarlo Pedrini, Wolfgang Osten.

Abstract:

“We demonstrate two methods based on Fourier plane filtering using (a) a fractional spiral phase plate (SPP) and (b) an off-axial SPP for phase contrast enhancement in optical microscopy. In comparison to previous works, a spatially incoherent LED is used in the Köhler illumination as the light source to illuminate the biological specimen. We demonstrate that both these methods can transform the phase specimen into a relief-like view even under such illumination. The degree and orientation of enhancement can be controlled by changing the phase structure of the filter. The SPP is displayed on a phase-only spatial light modulator, and can be integrated into the optical path of standard microscopes.”

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Publication: Optics Communications
Issue/Year: Optics Communications, Volume 283, Issue 7, 1 April 2010, Pages 1273–1277
DOI: 10.1016/j.optcom.2009.11.084

Wide viewing angle holographic display with a multi-spatial light modulator array

Author(s):

Finke, Grzegorz; Kozacki, Tomasz & Kujawi{‘{n}}ska, Ma{l}gorzata

Abstract:

“In the paper we present the design of a wide viewing angle display system capable of displaying digital holograms captured in a rotary CCD configuration. We have discussed the two possible configurations of multi LC SLMs system: with a normal LC SLM illumination and with tilted LC SLMs and parallel illumination. The second system was selected and the tilted plane algorithm, necessary for recalculation of displayed holograms was tested. Finally we have presented and discussed different means of visual perception of holographic images: with an asymmetric diffuser and with an eyepiece.”

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Publication: SPIE Proceedings, Volume 7723
Issue/Year: Proc. SPIE 7723, Optics, Photonics, and Digital Technologies for Multimedia Applications, 77230A , 2010
DOI: 10.1117/12.855778

Phase retrieval by means of a spatial light modulator in the Fourier domain of an imaging system

Author(s): Claas Falldorf, Mostafa Agour, Christoph v. Kopylow, and Ralf B. Bergmann

Abstract:

“We present an experimental configuration for phase retrieval from a set of intensity measurements. The key component is a spatial light modulator located in the Fourier domain of an imaging system. It performs a linear filter operation that is associated to the process of propagation in the image plane. In contrast to the state of the art, no mechanical adjustment is required during the recording process, thus reducing the measurement time considerably. The method is experimentally demonstrated by investigating a wave field scattered by a diffuser, and the results are verified by comparing them to those obtained from standard interferometry.”

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Publication: Applied Optics
Issue/Year: Applied Optics, Vol. 49, Issue 10, pp. 1826-1830 (2010)
DOI: 10.1364/AO.49.001826

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