Microscopes are an essential optical instrument for diagnostic purposes. Now, AI is included in these diagnostic processes with microscopes which has revolutionized this area of field. Diagnostic processes have become more accurate, efficient and less time consuming for pathologists and patients as well. This paper provides a detailed review of artificial intelligence (AI) enabled microscopy for diagnostic applications. Latest advancements in AI enabled microscopes are discussed, focusing on their applications in medical diagnostics. The review come up with a range of microscopy techniques and how AI algorithms help in real-time image analysis, recognition of abnormalities, and disease prediction. Moreover, challenges and opportunities associated with these smart microscopes are also determined. The purpose of this paper is to serve as a valuable resource for researchers, clinicians, and technologists who are working on AI-enabled microscope designs for diagnostic applications.
Dispersion management plays a critical role in advancing spectrometers, which are indispensable tools for comprehending various optical phenomena, such as Raman scattering and fluorescence. Spectrometers investigate spectral changes under light-matter interaction, targeting many real-life applications extending from food safety and disease diagnostics to environmental monitoring. Unlike their bulkier predecessors, compact spectrometers have significant potential for enhanced versatility and wearable optics. This study proposes a zinc sulfide-based, all-dielectric super dispersive, Circular Polarization (CP) discriminator metalens. The dispersion-controlled metalens is an integral component of compact spectrometers, with focal spots residing on the same plane and undergoing minimal broadening across the visible spectrum (i.e., 475 − 650 nm). Moreover, the proposed device fulfills an additional role as a CP filter, permitting one state to focus on the intended position while simultaneously defocusing the other. In practice, incorporating a novel spin-decoupling approach with wavelength and phase multiplexing equips the proposed device to provide optimal spectral resolving performance with helicity-resolved capabilities, making it a multifunctional state-of-the-art meta-spectrometer. We are confident that the proposed device effectively merges various advanced features, positioning it as a promising addition to spectrometry.
Structured light beams have attracted significant interest due to their versatile spatial or spatiotemporal configurations, which can potentially transform various real-world applications not achievable using conventional Gaussian beams. Bessel beams, with their non-diffracting properties, have proved themselves to be a phenomenal alternative in numerous scenarios where Gaussian beams were traditionally expected to excel. Therefore, numerous devices have been proposed to generate such non-diffracting beams via ultrathin and compact platforms of artificially engineered subwavelength thick structures, acknowledging the significance of chip-scale integration. However, selecting element/elements with their geometry influences and imposes limitations on many applications. Here, we demonstrate a geometric phase-based all-dielectric, highly efficient (≈ 80%) polarization-insensitive compact transmissive structure. Our metastructure utilizes zinc sulfide as an elementary material, designed to operate in the visible spectrum (475− 650 nm) due to its favorable optical constants. The proposed design philosophy is affirmed by a straightforward approach that effectively handles the persistent challenge of polarization-insensitive light structuring across a broader spectrum using a distinct single-cell-driven, single-layered metastructure. For proof of concept, numerical simulations utilizing the Finite Difference Time Domain (FDTD) method validate our idea, demonstrating second-order Bessel beams under various polarization states (e.g., linear and circular) for the visible spectrum. We are confident that generating polarization-independent Bessel beams of zeroth or higher order within a visible domain of the electromagnetic spectrum can unlock promising possibilities for numerous advanced applications, such as imaging, laser fabrication, optical manipulation, and beyond.
Vortex beams offer a novel avenue for advancing information transmission, storage, and processing within the optical domain. However, conventional optical apparatus and systems depend on the phase accumulation technique to create vortex beams. These methods frequently lead to the development of cumbersome and expensive configurations, hindering the integration with on-chip photonic systems. Metasurfaces, planar structures composed of nano-elements, hold immense promise for extensive adoption in optics and photonics. Their remarkable capacity to manipulate light at the nano-level has led to widespread utilization, particularly in generating optical vortices. In this work, we proposed an all-dielectric transmissive metasurface platform that generates a perfect vortex beam with a trigonometric function embedded in it to achieve an infinite topological charge. We selected silicon nitride (Si3N4) as the material of choice. It exhibits transparency in the ultraviolet (UV) region and across the visible spectrum. It also exhibits best-suited optical properties to ensure exceptional response in the targeted dual bands. We selected a numerical aperture of NA = 0.7 for verification of the concept, and two trigonometric functions are θ. cos(θ) and ½ sin(θ). The presented design technique and material may find potential applications in biomedicine, free-space optical data communications, and optical data modulation.
Effective dispersion management is critical in constructing super prism, spectrometers, and achromatic lens-based optical systems. Metasurfaces, the artificially engineered structures, promise the miniaturization of such dispersive devices to enable compactness and integration with on-chip devices. The miniaturization is due to the planar nature of the fundamental building blocks that offer unprecedented control of optical properties of light, such as phase, amplitude, and polarization. These building blocks abruptly vary the light characteristics to engineer the output behavior. The response of the metasurface depends upon geometry and material, which, in turn, is dependent on the wavelength of the incident light, amongst other factors. Conventional ways of dispersion management are not only complex but also give rise to aberration-related challenges. Metasurfaces provide alternatives to combat the above-said limitation. A single-layered, single-cell driven all-dielectric super dispersive metalens is not reported for the visible regime. Here, we proposed a zinc sulfide (ZnS) based highly dispersive metalens with a parabolic phase profile that operates in the visible spectrum and resolves the spectrum of the incident wave by dispersing different wavelengths to different positions at the edge of the metasurface for easy instrumentation integration. Simulations are carried out to verify the proposed design's theoretical dispersion characteristics. The proposed element's high transmission and polarization conversion efficiency ensure broad practical usage. The proposed metasurface can potentially be used in spectrometers, tomography, microscopy, etc.
Generating structured light beams has become a research hotspot to target many emerging practical applications like optical sensing, super-resolution imaging, and optical communication. Ingenious tailoring of spatial structures of light helps to manifest several intriguing beams like Bessel beams, Airy beams, vortex beams, etc. Among them, optical vortices (OVs) hold distinctive promise to meet the anticipated demands for optical communication, optical trapping, microscopy, quantum information processing, and many more. Due to their spatial dimensions, traditional methods of generating OVs are not viable to fit with the cutting-edge on-chip optical systems. In contrast, subwavelength structured devices enormously aggravate the capability to realize chip-integrated devices via abrupt phase discontinuity. Besides the many exotic features of optical metasurfaces, their fixed functionality limits the realization of breakthroughs in many real-life applications. Here, we present an exquisite design that enables multifunctional metastructures to develop multichannel focused optical vortices of like or distinct topological charges on the same focal plane regardless of the input polarization state. Our design is based on a symmetric array of nanocylinders where the index waveguide theory concept is utilized effectively to accumulate the desired phase in the direction of propagation. Moreover, zinc sulfide, as a prime material used in device prototyping, enables a highly transmissive structure. Our work regarding the multidimensional generation of optical vortices has far-reaching effects on multifunctional optical devices.
Light-matter interaction at the micron scale enables unprecedented control over different intrinsic properties of electromagnetic waves. Recently emerged ultrathin metamaterials (metasurfaces) featuring periodic nanoantennas are capable of controlling the amplitude, phase, and polarization states of the incident light and open up new avenues for a variety of exotic nanophotonic applications. Integrating multiple optical phenomena into a single nano-optical device has become a hotspot to increase the multi-functionality of the metasurfaces for functional multiplexing, notably reducing the intricacy of the existing optical setups. Herein, a multifunctional metalens operating at ultraviolet regime 𝜆𝑑 = 300 nm is reported, exploiting the approach of merging the Pancharatnam–Berry (PB) and propagation phases into a single metadevice. Through interleaving the different subwavelength rectangular and cylindrical shaped nanoantennas of silicon nitride (Si3N4) patterned on sapphire (Al2O3) substrate, the proposed meta-device results in a multifunctional metalens capable of focusing the incident light at three different focal spots on the same focal plane. The geometric parameters of both the nanoantennas (rectangular bar and cylindrical pillar) are optimized in such a way to achieve the maximum possible transmission intensity and complete phase coverage requirements for higher resolution focusing on making nanoscale features distinguishable. This attractive design topology of merging the multiple phases into a single device to realize a multifunctional meta-device can envision its promising application in imaging and optical communication.
In this paper, we present electrically tunable metasurfaces that exhibit multifunctional characteristics in the visible domain by exploiting electro-optic effect (EO). The metasurfaces consist of an array of Barium Titanate (BTO) meta-atoms on an Indium Titanium oxide (ITO) coated substrate. The resonance wavelength of the metasurface can be tuned by varying the electric field that eventually alters the refractive index of material. The tunability of resonance wavelength is evaluated by a hologram that appears at the desired wavelength by changing its voltage. Furthermore, a zoom metalens is presented with focal length shift by applying different electric fields at the wavelengths of 488, 532 and 633 in nm. The proposed idea can be useful for realizing tunable integrated systems.
Metasurfaces have gained considerable attention due to their control over light properties like phase, amplitude, and polarization, which benefitted the industry for their applications in digital displays and multimedia related applications. Miniaturization of the devices has always been an interesting domain for researchers that can be accomplished by enabling a device to perform multifunctional behavior. Here, we propose a meta-atom by breaking symmetry of spin orbit interactions resulting in polarization sensitive device that transmits and reflects simultaneously under different circular polarizations. A z-shaped silicon-based meta-atom is designed, which provides asymmetric transmission of 80 % and 74 % in reflection and transmission, respectively. We demonstrated polarization multiplexed holograms in transmission and reflection for proof of concept that reflects its potential in spin-controlled imaging and sensing devices.
Recently emerged metasurfaces, the two-dimensional (2D) counterpart of three dimensional (3D) metamaterials, gained significant attention in optics and photonics due to their less challenging fabrication requirements (compared to 3D metamaterials) and unique capabilities of wavefront manipulation by introducing abrupt phase shift. Realization of multiple functionalities in a single metasurface, is an intriguing perception to achieve further miniaturization and cost effectiveness. In this paper, we propose a polarization insensitive, highly efficient metasurfaces for the visible spectrum. For the design wavelength of 633nm, negligible absorption coefficient (k) and adequately large refractive index (n) of proposed hydrogenated amorphous silicon (a-Si:H) leads to considerably efficient and cost-effective solution towards metasurfaces design. Inherent property of cylindrical pillar to be polarization insensitive is exploited and 400 nm thick cylindrical nano–waveguide is opted as building block to construct the metasurface. A novel design strategy of achieving multiple functionalities from a single metasurface is proposed, where a combined effect of lensing and optical vortices with different topological charges at different focal planes is demonstrated for the proof of concept. Such unique design strategy of integrating multiple phases into a single device provides an innovative way of miniaturizing the optical devices and systems exhibiting versatile functionalities for on–chip applications.
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