Hybrid Optical Systems Research Articles

Hybrid Resonant Metasurfaces with Configurable Structural Colors

AbstractMetasurfaces are sub‐wavelength nanostructures with the potential to overcome the limitations of traditional optics. Existing dielectric metasurfaces, however, are often limited to geometric primitives, which hamper their application in emergent hybrid metasurfaces. Here, a simple fabrication scheme for non‐primitive metasurfaces that addresses this limitation is introduced. Due to their broken out‐of‐plane symmetry, these nanostructures provide a new dimension in the design space. Taking inspiration from bio‐photonic systems in nature, using these elements complex hybrid metasurfaces are designed that encompass an ordered and a disordered phase. The capabilities of this hybrid optical systems are illustrated by generating configurable structural colors with extra ordinary resolution. Furthermore, the local control of light over a broad bandwidth is demonstrated and a maximum coupling efficiency of more than 97% is achieved.

Noncontact optical device for measuring blood glucose in aqueous humor: a pilot clinical study investigating correlation with blood glucose levels.

Monitoring blood glucose levels is crucial for individuals with diabetes. Noninvasive methods for measuring serum glucose levels have been explored to aid in blood glucose control for diabetes management. We introduced a noncontact optical glucometer (NCGM) for measuring glucose levels in the aqueous humor of the human eye. We also investigated the correlation between glucose levels in the NCGM and the aqueous humor, blood samples, and self-monitoring blood glucose devices. The optical system used in this study measured both the near-infrared absorption and polarized rotatory distribution of glucose molecules in the human aqueous humor. This prospective study's outcomes were eye aqueous glucose level, preoperative blood glucose level, intraoperative blood glucose level, and NCGM reading of patients in a single center in Taiwan. The NCGM's measurements showed a strong correlation with blood glucose levels (intra-class correlation [ICC]: 0.95 to 0.98) and aqueous humor glucose levels (ICC: 0.76), indicating its ability to noninvasively measure blood glucose levels in human subjects. This NCGM may offer a convenient, pain-free, and rapid tool for measuring blood glucose levels in diabetic patients. The device could represent a significant advancement in noncontact hybrid optical glucose measurement systems.

Robust stabilization of fractional-order hybrid optical system using a single-input TS-fuzzy sliding mode control strategy with input nonlinearities

<p>Hybrid optical systems with integrated control mechanisms enable a dynamic adjustment of optical components, ensuring real-time optimization, adaptability to changing conditions, and precise functionality. This control requirement enhances their performance in applications demanding responsiveness, such as autonomous systems, adaptive optics, and advanced imaging technologies. This research introduces a novel approach, employing a dynamic-free Takagi-Sugeno fuzzy sliding mode control (TS-fuzzy SMC) technique, to regulate and stabilize a specific category of chaotic fractional-order modified hybrid optical systems. The method addresses uncertainties and input-saturation challenges within the system. Leveraging a novel fractional calculus definition along with the non-integer type of the Lyapunov stability theorem and linear matrix inequality principle, the TS-fuzzy SMC approach was applied to effectively mitigate and regulate the undesired behavior of the fractional-order chaotic-modified hybrid optical system. Notably, this scheme achieved control without experiencing undesirable chattering phenomena. The paper concludes by offering concrete examples and comparisons, demonstrating how the theoretical findings are applied in real-world scenarios. This provides practical insights into the effectiveness of the proposed approach in diverse applications.</p>

Digital-optical co-design enables athermalization of hybrid optical systems.

We proposed a digital-optical co-design that can effectively improve the image quality of refractive-diffractive hybrid imaging systems over a wide ambient temperature range. Diffraction theory was used to establish the degradation model and blind deconvolution image recovery algorithm was used to perform recovery for simulated images. The peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) were used to evaluate the algorithm performance. A cooled athermalization dual-band infrared optical system with a double-layer diffractive optical element (DLDOE) was designed, and the results show an overall improvement for both PSNR and SSIM overall the whole ambient temperature range. This demonstrates the effectiveness of the proposed method for the image quality improvement of hybrid optical systems.

Computational Imaging in Dual-Band Infrared Hybrid Optical System with Wide Temperature Range.

The special dispersion and temperature characteristics of diffractive optical element (DOE) make them widely used in optical systems that require both athermalization and achromatic aberrations designs. The multi-layer DOE (MLDOE) can improve the diffraction efficiency of the overall broad waveband, but its diffraction efficiency decreases with changes in ambient temperature. When the ambient temperature changes, the micro-structure heights of MLDOE and the refractive index of the substrate materials change, ultimately affecting its diffraction efficiency, and, further, the optical transform function (OTF). In this paper, the influence of ambient temperature on the diffraction efficiency of MLDOE in a dual-infrared waveband is proposed and discussed, the diffraction efficiency of MLDOE caused by ambient temperature is derived, and a computational imaging method that combines optical design and image restoration is proposed. Finally, a dual-infrared waveband infrared optical system with athermalization and achromatic aberrations corrected based on computational imaging method is designed. Results show that this method can effectively reduce the diffraction efficiency of MLDOE by ambient temperature and improve the imaging quality of hybrid optical systems.

Refractive-diffractive hybrid optics array: comparative analysis of simulation and experiments

Hybrid optical elements, which combine refractive and diffractive optical components to enhance optical performance by taking advantage of the optical characteristics of the individual components, have enormous potential for next-generation optical devices. However, there have not been many reports on the simulation methodology to characterize such hybrid optical systems. Here, we present a method for simulating a hybrid optical element realized by attaching an ultra-thin, flexible diffractive optics array onto a refractive optical element. The ultra-thin diffractive optical element is fabricated by direct-laser-writing using a femtosecond pulsed laser as the light source. A systematic investigation of the proposed simulation method, which does not require extensive hardware resources or computational time, but retains resolution and accuracy, is presented. The proposed scheme is validated by comparing simulation and experimental results. The simulation and experimental results on the spot size and focal length for the diffractive Fresnel zone plate (FZP) match well, with typical errors of less than 6%. The aspect ratio of the focal spot sizes at the compound and FZP focal planes of the hybrid optical system from the simulation and experiment also match quite well, with typical errors below 7%. This simulation scheme will expedite the designs for novel hybrid optical systems with optimal optical performances for specific applications, such as microfluidics and aberration-controlled optics.

Broadband, optically transparent and highly flexible multispectral beam splitter based on Ag nanowires/graphene composite film for hybrid optical systems

The research on novel terahertz (THz) devices with high performance is in rapid ascent in order to promote applications of THz technology. In this paper, we propose a broadband, optically transparent and highly flexible multispectral beam splitter based on Ag nanowires/graphene (ANWG) composite film on polyethylene terephthalate film substrates. The properties of the ANWG-based beam splitters are investigated, which exhibit a broadband THz reflectance of about 90%, a high optical transmittance of over 86% in the visible range, and excellent mechanical flexibility. The THz experimental result of the ANWG-based beam splitter is close to those of numerical simulations using a theoretical model. In comparison with conventional THz beam splitters, the ANWG-based beam splitter possesses excellent light-splitting performances for both transmitting visible light and reflecting THz radiation, and the device can significantly improve the overall performance of THz optical systems. Moreover, the device can be effectively applied in the visible/infrared imaging systems to implement multispectral imaging. Our concept provides a promising route for realizing compact hybrid optical systems, and it has great potential for commercial applications.

Analysis of the influence of antireflective coatings on the diffraction efficiency of diffractive optical elements.

Diffractive optical elements (DOEs) may be used as a single optical component with dedicated functionality (e.g. focusing), or as one of the elements in complex hybrid optical systems to reduce the number of the elements and improve imaging quality. It is desirable to cover DOE's surface with antireflective coating. In this paper, we show the results of simulations using the Fourier modal method and measure the efficiency of a diffractive lens with antireflective (AR) coating. Results were compared with a previously proposed model of AR covered DOE by Mao et al. [Opt. Express25, 11673 (2017)10.1364/OE.25.011673]. Contrary to the previously published model, we have not observed a shift of the efficiency curve. Our findings prove that AR coatings improve the efficiency of DOEs and it is not necessary to take them into account when calculating optimal profile height.

Generation and transfer of squeezed states in a cavity magnomechanical system by two-tone microwave fields.

We propose a scheme to generate squeezed states of magnon and phonon modes and verify squeezing transfer between different modes of distinct frequencies in a cavity magnomechanical system which is composed of a microwave cavity and a yttrium iron garnet sphere. We present that by activating the magnetostrictive force in the ferrimagnet, realized by driving the magnon mode with red-detuned and blue-detuned microwave fields, the driven magnon mode can be prepared in a squeezed state. Moreover, the squeezing can be transferred to the cavity mode via the cavity-magnon beamsplitter interaction with strong magnomechanical coupling. We show that under the weak coupling regime, large mechanical squeezing of phonon mode can be achieved, which verifies that our scheme can find the existence of quantum effects at macroscopic scales. Furthermore, distinct parameter regimes for obtaining large squeezing of the magnons and phonons are given, which is the principal feature of our scheme. The considered scheme can be extended to hybrid optical systems, and can facilitate the advancement for realization of strong mechanical squeezing in cavity magnomechanical systems.

Performance Analysis of All-optical PPM-mQAM Communication Systems

Increasing the spectral efficiency of transmission has increased interests in hybrid optical communication systems. However, these systems suffer from the nonlinear fiber impairments that produce nonlinear phase noise (NPN). In this paper, we investigate all-optical coding m-ary quadrature amplitude modulation (mQAM) by pulse position modulation (PPM) in a single channel optical communication system to increase the transmission capacity and reduce the NPN. The system performance that optically modulates the data by hybrid PPM-mQAM format is numerically investigated by simulation. The results show that the transmission capacity is duplicated and NPN is significantly moderated when PPM-4QAM and PPM-16QAM are used. At bit error rate (BER) of 10−4, the transmission distances of PPM-4QAM is increased by about 33%, in comparison to 4QAM system. In addition, the required optical signal-to-noise ratios (OSNRs) for achieving BER of 1×10−4 are decreased by 4.7 dB and 7.5 dB for the PPM-4QAM and PPM-16QAM schemes, respectively.

Design of high scalability multi-subcarrier rof hybrid system based on optical CDMA/TDM

<span>The technology of radio over fiber (RoF) regard a crucial point to solve problems in wireless communication system. As well as, the growth of internet applications also reveals a tremendous increase in bandwidth for different applications. Therefore, the development of optical networks is very important that have maximum bandwidth by using different multiple access techniques. Optical code division multiple access (OCDMA) technique has considered as a good solution for high bandwidth network. Hybrid optical systems of OCDMA and time division multiplexing (OTDM) has been proposed in this paper to increase the number of simultaneous users. The results of hybrid OCDMA and OTDM system demonstrate that this system can make a considerable increase in the network scalability while ensuring sufficient data rate and an acceptable bit error rate. Where M-user OCDMA signals can be transmitted in different channels of an OTDM system. Due to its wide band facility compared with other access techniques, OCDMA used here. In addition to its high scalability for our radio network, the OTDM and SCM utilized. The combination of these efficient access technique and powerful time-sharing media are lead to increase the framework system scalability.</span>

Design and analysis of a hybrid optical system containing a multilayer diffractive optical element with improved diffraction efficiency.

We present a compressive image quality evaluation for a hybrid optical system containing a multilayer diffractive optical element (MLDOE). We take effects from both incident angle and waveband into consideration to improve the diffraction efficiency of the MLDOE. With this MLDOE design, it can ensure accurate image quality evaluation for hybrid optical systems. The results show that this design enables a diffraction-efficiency-improved MLDOE, and further ensures accurate image quality of the modulation transfer function and better optical system structure of the hybrid surveillance lens. The results are of great significance for the optimal design of hybrid imaging optical systems.

Comprehensive polychromatic integral diffraction efficiency sensitivity to tilt error for multilayer diffractive optical elements with oblique incidence.

Oblique incidence is the general working state for multilayer diffractive optical elements (MLDOEs) in an imaging optical system. The polychromatic integral diffraction efficiency (PIDE) is very sensitive to the incident angle. Therefore, it is necessary to analyze the effect of tilt error on diffraction efficiency/PIDE with oblique incidence. The theoretical model of the relationship between the diffraction efficiency and tilt error with oblique incidence is presented, and the effect of tilt error on diffraction efficiency/PIDE is analyzed. The analysis model of comprehensive PIDE for a certain range of incident angles and the tilt error for MLDOEs is established. The simulation results showed that the comprehensive PIDE is sensitive to tilt angle with oblique incidence, and the tolerance of the tilt error angle can be determined by the comprehensive PIDE. The tilt error tolerance is furthermore investigated with decenter error based on the maximum of comprehensive PIDE. The method and results can be used to guide the tolerance formulation of tilt error for MLDOEs in hybrid optical systems.

Principles for developing hybrid surgical eyeglasses

Polymeric materials are actively used in new optical devices. Modern advances in the synthesis, manufacture, and processing of polymers make it possible to use them in manufacturing hybrid optical systems. This article presents the results of the development of surgical hybrid eyeglasses using components from polymer optical materials. The results indicate that the obtained optical system, including components made of glass and polymers, has good image quality, low mass, and compactness.

Integral diffraction efficiency model for multilayer diffractive optical elements with wide angles of incidence in case of polychromatic light.

Oblique incidence is the normal working mode for diffractive optical elements (DOEs). The diffraction efficiency is very sensitive to the angle of incidence for multilayer diffractive optical elements (MLDOEs). Therefore, the design and diffraction efficiency analysis of MLDOEs with wide angles of incidence is of universal significance and practice. We propose an integral diffraction efficiency model for MLDOEs with wide angles of incidence in case of polychromatic light and then describe this corresponding optimal design in detail. It is shown that high diffraction efficiency can be realized by the surface micro-structure heights optimization, ensuring high modulation transfer function (MTF) for MLDOEs with wide angles of incidence in hybrid optical systems. On this basis, we present the optimal design process and simulation of an MLDOE working in visible waveband with optical plastic materials combination PMMA and POLYCARB as the two-layer substrates. The result shows that with this optimal design, we can achieve the maximum diffraction efficiency and minimum micro-structure heights, which makes the MLDOE design exactly over the entire waveband and wide angles of incidence especially for zoom hybrid optical system.

Transferable ultra-thin multi-level micro-optics patterned by tunable photoreduction and photoablation for hybrid optics

Next-generation hybrid optics will provide superior performances over traditional optics by combining the advantages of refractive, reflective, and diffractive optics and metasurfaces. Hybrid optics have been realized by integrating diffractive optical structures to the top surface of traditional bulk refractive or reflective optics. However, high-resolution manufacturing requirement of diffractive patterns on top of free-form refractive or reflective optical surfaces have hindered the wide-spread dissemination of hybrid optics. In this paper, we demonstrate a transferable ultra-thin micro-optics having multi-level transmittance and phase profiles which are arbitrarily patterned by tunable photoreduction and photoablation of graphene oxides (GO) using femtosecond (fs) direct laser writing. A 5 × 5 array of multi-level ultra-thin micro diffractive lens having a focal length of 15 mm was exemplarily patterned with real-time laser power control; the resulting spot size was smaller than 14 μm with the suppression of diffractive side peaks by 14.9% at the first order and 10.8% at the second order ones. This laser-patterned diffractive lens array was successfully transferred to the surface of a refractive cylindrical lens via polydimethylsiloxane (PDMS) as the flexible/stretchable substrate; the resulting optical performance agrees well with the theoretical simulation result. This new fabrication method will pave a way to novel hybrid optical systems.

Tolerance analysis on decenter error of multilayer diffractive optical elements based on polychromatic integral diffraction efficiency.

The decenter error can determine the polychromatic integral diffraction efficiency (PIDE) over a broad wave band of hybrid optical systems and further the imaging quality. The mathematical model of the relationship between the decenter error and the PIDE of multilayer diffractive optical elements (MLDOEs) is presented, and the expressions are derived based on phase delay of diffractive optical elements for both normal and oblique incident situations. Finally, the sensitivity of PIDE to the decenter error for MLDOEs used in a long-infrared wave band with a material combination of ZNS-ZNSE is analyzed, and then the decenter error tolerance is proposed to ensure high PIDE over a broad wave band as well as diffraction efficiency at the designed wavelengths. The analysis methods and results could be useful for guiding the decenter error of MLDOEs in hybrid optical systems for optical engineers.

Optimization method of multilayer diffractive optical elements with consideration of ambient temperature.

A method for the optimal design of multilayer diffractive optical elements (MLDOEs) with consideration of ambient temperature is presented to improve the image quality over the entire temperature range. The relationship between diffraction efficiency and temperature is analyzed, and an optimization process of surface relief height for the MLDOEs is given. A practical 3-5μm athermal hybrid optical system with a double-layer diffractive optical element is designed in the temperature range from -20°C to 60°C, and the image quality of two hybrid optical systems with optimized MLDOE and original MLDOE is compared. The result shows that the comprehensive modulation transfer function is obviously improved in the whole working temperature range. This method can be used during the passive athermalization hybrid optical system design with MLDOEs.

Optimal design method for multi-layer diffractive optical elements with consideration of antireflection coatings

An optimal design method for multi-layer diffractive optical elements (MLDOEs) is put forward with consideration of antireflection coatings in actual applications of hybrid optical systems. Taking this method into account for optimal design, it can ensure 100% diffraction efficiency at the designed wavelengths and maximum polychromatic integral diffraction efficiency over the whole waveband. In addition, it can be obtained not only for mechanical durability of soft polymers improvements but increase antireflection coatings functions for hybrid optical systems. Finally, an example for optimal design algorithm process and simulation of MLDOEs used in visible waveband is presented. The results show that this optimal method perfects the MLDOEs design on the basic theory with great practicability for MLDOEs design.

Digital holographic interferometry for cultural heritage structural diagnostics: A coherent and a low‐coherence optical set‐up for the study of a marquetry sample

AbstractCultural heritage conservation is an active field of research, where there is an ever‐growing demand for nondestructive and noninvasive diagnostic techniques, for performing remote analysis and diagnosis of the condition of historical structures and pieces of art, often of very high cultural and historical value. In this context, holographic interferometry is a very well‐established optical technique for research in cultural heritage, which brings together some very basic and critical properties such as contactless examination and nondestructivity, accuracy, repeatability, and a wide range of applicability. In this paper, the optical technique of digital holographic interferometry is tested on mock‐up, art‐related targets, with 2 different light sources, in an attempt to expand the technique towards a new approach that will profit from an easy‐to‐operate, inexpensive, and tunable source, offering a broad spectrum and wavelength selectivity, according to the needs of the experiments. Examples are presented, and the results demonstrate the effectiveness of the proposed modified experimental scheme for defect mapping, to be used in structural documentation reports, and for its exploitation in future hybrid optical diagnostic systems and data processing.