scholarly journals Reducing Computational Complexity and Memory Usage of Iterative Hologram Optimization Using Scaled Diffraction

2020 ◽  
Vol 10 (3) ◽  
pp. 1132 ◽  
Author(s):  
Tomoyoshi Shimobaba ◽  
Michal Makowski ◽  
Takayuki Takahashi ◽  
Yota Yamamoto ◽  
Ikuo Hoshi ◽  
...  
Keyword(s):  
Computational Complexity ◽  
Light Propagation ◽  
Iterative Algorithms ◽  
Complex Amplitude ◽  
Spatial Light Modulators ◽  
Memory Usage ◽  
Light Modulators ◽  
Light Waves ◽  
Hologram Plane

A complex amplitude hologram can reconstruct perfect light waves. However, as there are no spatial light modulators that are able to display complex amplitudes, we need to use amplitude, binary, or phase-only holograms. The images reconstructed from such holograms will deteriorate; to address this problem, iterative hologram optimization algorithms have been proposed. One of the iterative algorithms utilizes a blank area to help converge the optimization; however, the calculation time and memory usage involved increases. In this study, we propose to reduce the computational complexity and memory usage of the iterative optimization using scaled diffraction, which can calculate light propagation with different sampling pitches on a hologram plane and object plane. Scaled diffraction can introduce a virtual blank area without using physical memory. We further propose a combination of scaled diffraction-based optimization and conventional methods. The combination algorithm improves the quality of a reconstructed complex amplitude while accelerating optimization.

scholarly journals Modern Types of Axicons: New Functions and Applications

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6690
Author(s):  
Svetlana N. Khonina ◽  
Nikolay L. Kazanskiy ◽  
Pavel A. Khorin ◽  
Muhammad A. Butt
Keyword(s):  
Intensity Distribution ◽  
Integrated Circuit ◽  
Bessel Beam ◽  
Optical Element ◽  
Spatial Light Modulators ◽  
Optical Antennas ◽  
Optical Elements ◽  
Photonic Integrated Circuit ◽  
Light Modulators

Axicon is a versatile optical element for forming a zero-order Bessel beam, including high-power laser radiation schemes. Nevertheless, it has drawbacks such as the produced beam’s parameters being dependent on a particular element, the output beam’s intensity distribution being dependent on the quality of element manufacturing, and uneven axial intensity distribution. To address these issues, extensive research has been undertaken to develop nondiffracting beams using a variety of advanced techniques. We looked at four different and special approaches for creating nondiffracting beams in this article. Diffractive axicons, meta-axicons-flat optics, spatial light modulators, and photonic integrated circuit-based axicons are among these approaches. Lately, there has been noteworthy curiosity in reducing the thickness and weight of axicons by exploiting diffraction. Meta-axicons, which are ultrathin flat optical elements made up of metasurfaces built up of arrays of subwavelength optical antennas, are one way to address such needs. In addition, when compared to their traditional refractive and diffractive equivalents, meta-axicons have a number of distinguishing advantages, including aberration correction, active tunability, and semi-transparency. This paper is not intended to be a critique of any method. We have outlined the most recent advancements in this field and let readers determine which approach best meets their needs based on the ease of fabrication and utilization. Moreover, one section is devoted to applications of axicons utilized as sensors of optical properties of devices and elements as well as singular beams states and wavefront features.

scholarly journals Shaping complex microwave fields in reverberating media with binary tunable metasurfaces

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Nadège Kaina ◽  
Matthieu Dupré ◽  
Geoffroy Lerosey ◽  
Mathias Fink
Keyword(s):  
Free Space ◽  
Light Propagation ◽  
Good Control ◽  
Spatial Light Modulators ◽  
Scattering Media ◽  
Energy Feedback ◽  
Light Modulators ◽  
Receiving Antenna ◽  
Order Of Magnitude ◽  
Electronically Tunable

Abstract In this article we propose to use electronically tunable metasurfaces as spatial microwave modulators. We demonstrate that like spatial light modulators, which have been recently proved to be ideal tools for controlling light propagation through multiple scattering media, spatial microwave modulators can efficiently shape in a passive way complex existing microwave fields in reverberating environments with a non-coherent energy feedback. Unlike in free space, we establish that a binary-only phase state tunable metasurface allows a very good control over the waves, owing to the random nature of the electromagnetic fields in these complex media. We prove in an everyday reverberating medium, that is, a typical office room, that a small spatial microwave modulator placed on the walls can passively increase the wireless transmission between two antennas by an order of magnitude, or on the contrary completely cancel it. Interestingly and contrary to free space, we show that this results in an isotropic shaped microwave field around the receiving antenna, which we attribute again to the reverberant nature of the propagation medium. We expect that spatial microwave modulators will be interesting tools for fundamental physics and will have applications in the field of wireless communications.

Mode purities of Laguerre–Gaussian beams generated via complex-amplitude modulation using phase-only spatial light modulators

2008 ◽  
Vol 34 (1) ◽  
pp. 34 ◽  
Author(s):  
Taro Ando ◽  
Yoshiyuki Ohtake ◽  
Naoya Matsumoto ◽  
Takashi Inoue ◽  
Norihiro Fukuchi
Keyword(s):  
Amplitude Modulation ◽  
Complex Amplitude ◽  
Spatial Light Modulators ◽  
Gaussian Beams ◽  
Light Modulators

Measurement of phase modulation of LCOS SLM Santec SLM-200 and analysis of its applicability for optical reconstruction of images from diffractive elements

2021 ◽  
pp. 4-8
Author(s):  
Nickolay N. Evtikhiev ◽  
Vitaly V. Krasnov ◽  
Ilya P. Ryabcev ◽  
Vladislav G. Rodin ◽  
Rostislav S. Starikov ◽  
...  
Keyword(s):  
High Resolution ◽  
Phase Shift ◽  
Digital Signal ◽  
Spatial Light Modulators ◽  
Optical Elements ◽  
Light Modulators ◽  
Phase Liquid ◽  
Optical Reconstruction ◽  
Diffraction Optical Elements

Phase liquid crystal (LC) spatial light modulators (SLM) are widely used for optical reconstruction of diffraction optical elements, including holograms. For this purpose high stability and linearity of phase response of SLM is required. In modern high resolution SLM digital signal addressing scheme which leads to emergence of effect of phase shift fluctuations during frame time is applied. In this paper measurements of character and peculiarities of modulation of phase shift of modern high-resolution LC SLM Santec SLM-200 were performed. Optical reconstruction of images from diffraction elements of different types was carried out, the quality of reconstruction and diffraction efficiency were assessed.

Giant Anisotropy of Conductivity in Hydrogenated Nanocrystalline Silicon Thin Films

1998 ◽  
Vol 536 ◽  
Author(s):  
A. B. Pevtsov ◽  
N. A. Feoktistov ◽  
V. G. Golubev
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Percolation Theory ◽  
Nanocrystalline Silicon ◽  
Spatial Light Modulators ◽  
Light Emitting ◽  
Light Modulators ◽  
Silicon Thin Films ◽  
Longitudinal Conductivity ◽  
Transverse Conductivity

AbstractThin (<1000 Å) hydrogenated nanocrystalline silicon films are widely used in solar cells, light emitting diodes, and spatial light modulators. In this work the conductivity of doped and undoped amorphous-nanocrystalline silicon thin films is studied as a function of film thickness: a giant anisotropy of conductivity is established. The longitudinal conductivity decreases dramatically (by a factor of 109 − 1010) as the layer thickness is reduced from 1500 Å to 200 Å, while the transverse conductivity remains close to that of a doped a- Si:H. The data obtained are interpreted in terms of the percolation theory.

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