High-Flexibility Control of Structured Light with Combined Adaptive Optical Systems

Combining the specific advantages of high-resolution liquid-crystal-on-silicon spatial light modulators (LCoS-SLMs) and reflective or refractive micro-electro-mechanical systems (MEMS) presents new prospects for the generation of structured light fields. In particular, adaptive self-apodization schemes can significantly reduce diffraction by low-loss spatial filtering. The concept enables one to realize low-dispersion shaping of nondiffracting femtosecond wavepackets and to temporally switch, modulate or deflect spatially structured beams. Adaptive diffraction management by structured illumination is demonstrated for piezo-based and thermally actuated axicons, spiral phase plates (SPPs) and Fresnel bi-mirrors. Improved non-collinear autocorrelation with angular-tunable Fresnel-bi-mirrors via self-apodized illumination and phase contrast of an SLM is proposed. An extension of the recently introduced nondiffractive Talbot effect to a tunable configuration by combining an SLM and a fluid lens is reported. Experimental results for hexagonal as well as orthogonal array beams are presented.

Generation of high-uniformity and high-resolution Bessel beam arrays through all-dielectric metasurfaces

Bessel beam arrays are progressively attracting attention in recent years due to their remarkable non-diffracting nature and parallel manipulation capabilities in diverse applications. However, the poor phase discretization of conventional approaches such as spatial light modulators leads to low numerical aperture (NA) beam arrays due to the limitation imposed by the Nyquist sampling theorem and poor uniformity of the beam intensity. The key contribution of this study is to experimentally demonstrate the generation of high-uniformity and high-resolution Bessel beam arrays by utilizing all-dielectric metasurfaces. This is attained by optimizing the design of the supercell of a Dammann grating, particularly decreasing each supercell of the grating to a proper size. We demonstrate a 4 × 4 array of Bessel beams with a subwavelength transverse dimension (570 nm, ∼0.9λ) and a large NA of 0.4 for each beam in the array, while maintaining a relatively high uniformity intensity (52.40%) for the array. Additionally, the Bessel beam arrays are generated in a broadband range through the proposed all-dielectric metasurfaces. Our results are of great significance and particularly useful for applications of metasurface-based Bessel beam arrays in multidisciplinary fields such as laser fabrication, biomedical imaging, data storage, and multi-particle trapping.

LCOS Spatial Light Modulator for Digital Holography

Liquid crystal on silicon (LCOS) spatial light modulator (SLM) is the most widely used optical engine for digital holography. This paper aims to provide an overview of the applications of phase-only LCOS in two-dimensional (2D) holography. It begins with a brief introduction to the holography theory along with its development trajectory, followed by the fundamental operating principle of phase-only LCOS SLMs. Hardware performance of LCOS SLMs (in terms of frame rate, phase linearity and flicker) and related experimental results are presented. Finally, potential improvements and applications are discussed for futuristic holographic displays. Full Text: PDF ReferencesM. Wolfke, Physikalische Zeitschrift 21, 495 (1920). DirectLink D. Gabor, "A New Microscopic Principle", Nature 161, 777 (1948). CrossRef H. Haken, "Laser Theory", Light and Matter 5, 14 (1970). CrossRef S. Benton, "Selected Papers on Three-dimensional displays", SPIE Press (2001). DirectLink X. Liang et al, "3D holographic display with optically addressed spatial light modulator", 3DTV-CON 2009 - 3rd 3DTV-Conference (2009). CrossRef J. Chen, W. Cranton, M. Fihn, "Handbook of Visual Display Technology", Springer (2012). CrossRef D. Rogers, "The chemistry of photography: From classical to digital technologies", Royal Society of Chemistry (2007). CrossRef S. Reichelt et al, "Depth cues in human visual perception and their realization in 3D displays", Proc. SPIE 7690, 76900B (2010). CrossRef A.W. Lohmann, D. Paris, "Binary Fraunhofer Holograms, Generated by Computer", Appl. Opt. 6, 1739 (1967). CrossRef J.W. Goodman, R.W. Lawrence, "Digital Image Formation from Electronically Detected Hologtrams", Appl. Phys. Lett 17, 77 (1967). CrossRef D.C. O'Brien, R.J. Mears, and W.A. Crossland, "Dynamic holographic interconnects that use ferroelectric liquid-crystal spatial light modulators", Appl. Opt. 33, 2795, (1994). CrossRef R.W. Gerchberg, and W.O. Saxton, "A practical algorithm for the determination of phase from image and diffraction plane pictures", Optik 35, 237 (1972). DirectLink M. Ernstoff, A. Leupp, M. Little, and H. Peterson, "Liquid crystal pictorial display", Proceedings of the 1973 International Electron Devices Meeting, IEEE, 548 (1973). CrossRef W.A. Crossland, P.J. Ayliffe, and P.W. Ross, "A dyed-phase-change liquid crystal display over a MOSFET switching array", Proc SID 23, 15 (1982). DirectLink M. Tang, and J. Wu, "Optical Correlation recoginition based on LCOS", Internation Symposium on Photoelectronic Detection and Imaging 2013, Optical Storage and Display Tech., 8913 (2013). CrossRef A. Hermerschmidt, et al. Holographic optical tweezers with real-time hologram calculation using a phase-only modulating LCOS-based SLM at 1064 nm, Complex Light and Optical Forces II, International Society for Optics and Photonics, 30282 (2008). CrossRef M. Wang, et al. "LCoS SLM Study and Its Application in Wavelength Selective Switch", Photonics 4, 22 (2017). CrossRef Z. Zhang, Z. You, and D. Chu, "Fundamentals of phase-only liquid crystal on silicon (LCOS) devices", Light Sci. & Appls. 3, e213 (2014). CrossRef D. Yang, and S. Wu, Fundamentals of liquid crystal devices, 2nd edition (Wiley 2015). CrossRef B. Prince, Semiconductor memories: A handbook of design, manufacture, and application, 2nd ed. (John Wiley & Sons 1996). DirectLink J.C. Jones, Liquid crystal displays, Handbook of optoelectronics: Enabling Technologies, 2nd ed. (CRC Press 2018). DirectLink A. Ayriyan, et al. "Simulation of the Static Electric Field Effect on the Director Orientation of Nematic Liquid Crystal in the Transition State", Phys. Wave Phenom. 27, 67 (2019). CrossRef S.M. Kelly, and M. O'Neil, Liquid crystal for electro-optic applications, Handbook of advanced electronics and photonic materials and devices 7, 15 (2000). DirectLink Y. Ji, et al., "Suspected Intraoperative Anaphylaxis to Gelatin Absorbable Hemostatic Sponge", J. SID 22, 4652 (2015). CrossRef X. Chang, Solution-processed ZnO nanoparticles for optically addressed spatial light modulator and other applications, Ph.D. thesis, (University of Cambridge, Cambridge 2019) CrossRef E. Moon, et al. "Holographic head-mounted display with RGB light emitting diode light source", Opt. Express 22, 6526 (2014). CrossRef G. Aad, et al. "Study of jet shapes in inclusive jet production in pp collisions at √s=7 TeV using the ATLAS detector", Phys Rev. D 83, 052003 (2011). CrossRef M. Pivnenko, K. Li, and D. Chu, "Sub-millisecond switching of multi-level liquid crystal on silicon spatial light modulators for increased information bandwidth", Opt. Express 29, 24614 (2021). CrossRef H. Yang, and D.P. Chu, "Phase flicker optimisation in digital liquid crystal on silicon devices", Opt. Express 27, 24556 (2019). CrossRef P. Bach-Y-Rita, et al. "Seeing with the Brain", Int. J. Hum. -Comput. Interact 15, 285 (2003). CrossRef Y. Tong, M. Pivnenko, and D. Chu, "Improvements of phase linearity and phase flicker of phase-only LCoS devices for holographic applications", Appl. Opt. 58, G248 (2019). CrossRef Y. Tong, M. Pivnenko, and D. Chu, "Implementation of 10-Bit Phase Modulation for Phase-Only LCOS Devices Using Deep Learning", Adv. Dev. & Instr. 1, 10 (2020). CrossRef H. Yang, and D. Chu, "Phase flicker optimisation in digital liquid crystal on silicon devices", Opt. Express 27, 24556 (2019). CrossRef J. García-Márquez, et al. "Mueller-Stokes characterization and optimization of a liquid crystal on silicon display showing depolarization", Opt.Express 16, 8431 (2008). CrossRef

Optically Tunable and Thermally Erasable Terahertz Intensity Modulators Using Dye-Doped Liquid Crystal Cells with Metasurfaces

A terahertz metasurface that is imbedded into a dye-doped liquid crystal (DDLC) cell is fabricated in this work. After the metasurface-imbedded DDLC cell is irradiated with a linearly polarized pump beam, the irradiated cell is measured with a terahertz spectrometer. The irradiation of the pump beam causes the adsorption of the dye on one of the substrates of the cell, scattering incident terahertz waves and decreasing the transmittances of the terahertz metasurface at all the frequencies of its resonance spectrum. In addition, these transmittances decrease with an increase in the irradiation times of the pump beam. The adsorbed dye molecules are erased from the substrate after the cell is heated by a hot plate. The cell has similar spectra before the irradiation of the pump beam and after the heating of the hot plate. The aforementioned results reveal that the metasurface-imbedded DDLC cell is an optically tunable and thermally erasable terahertz intensity modulator. Therefore, this cell has the potential in developing intensity attenuators for terahertz imaging, frequency isolators for terahertz telecommunication, and spatial light modulators for terahertz information encryption and decryption.

Nanostructured silica spin–orbit optics for modal vortex beam shaping

Modality is a generic concept of wave-optics at the basis of optical information and communications. One of the challenges of photonics technologies based on optical orbital angular momentum consists in the production of a modal content for both the azimuthal and radial degrees of freedom. This basically requires shaping the complex amplitude of an incident light beam, which is usually made up from adaptive spatial light modulators or bespoke devices. Here, we report on the experimental attempt of a recent theoretical proposal [Opt. Lett. 42, 1966 (2017)] toward the production of various optical vortex modes of the Laguerre–Gaussian type relying on the spin–orbit interaction of light. This is done in the visible domain from optical elements made out of silica glass. The idea consists in exploiting the combined effects of azimuthally-varying geometric phase with that of radially-varying propagation features. The proposed approach can be readily extended to any wavelength as well as to other families of optical modes, although some dynamic phase problems remain to be solved to make it a turnkey technology.

Focal beam structuring by triple mixing of optical vortex lattices

On-demand generation and reshaping of arrays of focused laser beams is highly desired in many areas of science and technology. In this work, we present a versatile approach for laser beam structuring in the focal plane of a lens by triple mixing of square and/or hexagonal optical vortex lattices (OVLs). In the artificial far field the input Gaussian beam is reshaped into ordered arrays of bright beams with flat phase profiles. This is remarkable, since the bright focal peaks are surrounded by hundreds of OVs with their dark cores and two-dimensional phase dislocations. Numerical simulations and experimental evidences for this are shown, including a broad discussion of some of the possible scenarios for such mixing: triple mixing of square-shaped OVLs, triple mixing of hexagonal OVLs, as well as the two combined cases of mixing square-hexagonal-hexagonal and square-square-hexagonal OVLs. The particular ordering of the input phase distributions of the OV lattices on the used spatial light modulators is found to affect the orientation of the structures ruled by the hexagonal OVL. Reliable control parameters for the creation of the desired focal beam structures are the respective lattice node spacings. The presented approach is flexible, easily realizable by using a single spatial light modulator, and thus accessible in many laboratories.

Silicon-Based All-Dielectric Metasurface on an Iron Garnet Film for Efficient Magneto-Optical Light Modulation in Near IR Range

All-dielectric nanostructures provide a unique low-loss platform for efficiently increasing light-matter interaction via excitation of the localized or propagating optical modes. Here, we report on the transverse magneto-optical Kerr effect enhancement in an all-dielectric metasurface based on a two-dimensional array of Si nanodisks on a cerium substituted dysprosium iron garnet thin film. We observed up to 15% light intensity modulation under TM modes excitation. The observed magneto-optical effect is nearly independent of the rotation of the light incidence plane with respect to the metasurface. Being compatible with conventional semiconductor technology, our structure holds promise for device applications, such as light modulators, magnetic and chemical sensors.

Artifact-free holographic light shaping through moving acousto-optic holograms

Holographic light modulation is the most efficient method to shape laser light into well-defined patterns and is therefore the means of choice for many intensity demanding applications. During the last two decades, spatial light modulators based on liquid crystals prevailed among several technologies and became the standard tool to shape light holographically. But in the near future, this status might be challenged by acousto-optic deflectors. These devices are well known for their excelling modulation rates and high optical power resilience. But only few scattered precedents exist that demonstrate their holographic capabilities, despite the many interesting properties that they provide. We implemented a holographic acousto-optic light modulation (HALM) system, that is based on displaying holograms on acousto-optic deflectors. We found that this system can eliminate the ubiquitous coherent artifacts that arise in holography through the inherent motion of acousto-optic holograms. That distinguishes our approach from any other holographic modulation technique and allows to reconstruct intensity patterns of the highest fidelity. A mathematical description of this effect is presented and experimentally confirmed by reconstructing images holographically with unprecedented quality. Our results suggest that HALM promotes acousto-optic deflectors from highly specialized devices to full-fledged spatial light modulators, that can compete in a multitude of applications with LC-SLMs. Especially applications that require large optical output powers, high modulation speeds or accurate gray-scale intensity patterns will profit from this technology. We foresee that HALM may play a major role in future laser projectors and displays, structured illumination microscopy, laser material processing and optical trapping.