To manage engineered interferences and ultrashort light pulses, optical delay lines precisely control the temporal flow of light, inducing phase and group delays. For the purpose of chip-scale lightwave signal processing and pulse control, photonic integration of such optical delay lines is necessary. Typically, photonic delay lines, which rely on long spiral waveguides, present a challenge with their substantial chip size requirements, ranging from millimeters squared to centimeters squared. For a high-density, scalable integrated delay line, a skin-depth-engineered subwavelength grating waveguide is employed. This waveguide is referred to as an extreme skin-depth (eskid) waveguide. Crosstalk between adjacent waveguides is notably reduced by the eskid waveguide, resulting in a considerable saving of chip real estate. Scalability is a key feature of our eskid-based photonic delay line, which can be readily enhanced by increasing the number of turns, leading to improved photonic chip integration density.
Employing a multi-modal fiber array snapshot technique (M-FAST), we capture images using a 96-camera array positioned behind a primary objective lens and a fiber bundle array. The capacity of our technique extends to large-area, high-resolution, multi-channel video acquisition. A novel optical configuration, accommodating planar camera arrays, and the capability to acquire multi-modal image data are two pivotal enhancements offered by the proposed design over prior cascaded imaging systems. The M-FAST system, a multi-modal and scalable imaging platform, is engineered to capture snapshot dual-channel fluorescence images and differential phase contrast data within a 659mm x 974mm field-of-view with a 22-μm center full-pitch resolution.
Terahertz (THz) spectroscopy, while demonstrating great prospects in fingerprint sensing and detection, suffers from constraints in traditional sensing schemes when applied to the analysis of trace samples. For trace-amount samples, this letter proposes a novel absorption spectroscopy enhancement strategy, based on a defect one-dimensional photonic crystal (1D-PC) structure, for achieving strong wideband terahertz wave-matter interactions. Using the Fabry-Perot resonance effect, the local electric field within a thin-film specimen can be strengthened by varying the photonic crystal defect cavity's length, consequently improving the wideband signal that uniquely identifies the sample's fingerprint. The technique employed displays a substantial enhancement in absorption, approximately 55 times greater, across a broad terahertz frequency spectrum. This facilitates the identification of a variety of samples, such as thin lactose films. This Letter's investigation reveals a new avenue for researching how to enhance the broad terahertz absorption spectroscopy technique for the analysis of trace materials.
The three-primary-color chip array is the most elementary approach for designing and constructing full-color micro-LED displays. Genetic forms The AlInP-based red micro-LED and the GaN-based blue/green micro-LEDs show a substantial disparity in their luminous intensity distribution, resulting in an angular color shift that varies across different viewing angles. Regarding conventional three-primary-color micro-LEDs, this letter examines the angular dependence of color difference, highlighting that an inclined sidewall uniformly coated with silver has a limited effect on angular regulation. In view of this, a structured arrangement of conical microstructures is designed into the bottom layer of the micro-LEDs, with the explicit aim of fully correcting any color shift. Furthermore, this design regulates the emission of full-color micro-LEDs perfectly in line with Lambert's cosine law without employing external beam shaping components, and concurrently increases top emission light extraction efficiency by 16%, 161%, and 228% for red, green, and blue micro-LEDs, respectively. The full-color micro-LED display, with a viewing angle from 10 to 90 degrees, exhibits a color shift (u' v') that consistently remains below 0.02.
Currently, most UV passive optics lack tunability and external modulation options due to the limited tunability of wide-bandgap semiconductor materials within UV operational environments. Within this study, the excitation of magnetic dipole resonances in the solar-blind UV region is examined via hafnium oxide metasurfaces, using elastic dielectric polydimethylsiloxane (PDMS). Infiltrative hepatocellular carcinoma The mechanical strain imposed on the PDMS substrate can modulate the near-field interactions between the resonant dielectric elements, potentially flattening the structure's resonant peak beyond the solar-blind UV wavelength range and thereby enabling or disabling the optical switch in the solar-blind UV region. The design of the device is straightforward, enabling its use in diverse applications, including UV polarization modulation, optical communication, and spectroscopy.
This paper introduces a geometrically-based screen modification approach that effectively removes ghost reflections typically seen in deflectometry optical testing. The proposed methodology adjusts the optical layout and the size of the illumination source in order to circumvent the formation of reflected rays from the unwanted surface. System layouts using deflectometry can be specifically designed to prevent the occurrence of secondary rays that interrupt the process. Case studies involving convex and concave lenses showcase the effectiveness of the proposed method, backed by results from optical raytrace simulations. The digital masking method, in its final analysis, has limitations that are discussed.
High-resolution three-dimensional (3D) refractive index (RI) distribution of biological specimens is obtained from 3D intensity-only measurements using the recently developed label-free computational microscopy technique, Transport-of-intensity diffraction tomography (TIDT). Although the non-interferometric synthetic aperture in TIDT is attainable sequentially, it necessitates the acquisition of numerous intensity stacks at diverse illumination angles, producing a significantly cumbersome and redundant data collection procedure. We furnish a parallel synthetic aperture implementation in TIDT (PSA-TIDT) with annular illumination, with this in mind. An annular illumination pattern yielded a mirror-symmetrical 3D optical transfer function, which suggests analyticity of the complex phase function in the upper half-plane; consequently, this facilitates 3D refractive index recovery from a single intensity stack. By utilizing high-resolution tomographic imaging, we experimentally corroborated the accuracy of PSA-TIDT on a diverse set of unlabeled biological samples, including human breast cancer cell lines (MCF-7), human hepatocyte carcinoma cell lines (HepG2), Henrietta Lacks (HeLa) cells, and red blood cells (RBCs).
The generation of orbital angular momentum (OAM) modes in a long-period onefold chiral fiber grating (L-1-CFG), constructed from a helically twisted hollow-core antiresonant fiber (HC-ARF), is investigated. Utilizing a right-handed L-1-CFG as a prime example, we demonstrate both theoretically and experimentally that inputting a Gaussian beam alone can generate the first-order OAM+1 mode. We constructed three right-handed L-1-CFG samples, employing helically twisted HC-ARFs with twist rates of -0.42 rad/mm, -0.50 rad/mm, and -0.60 rad/mm. The HC-ARF with a -0.42 rad/mm twist rate achieved a notable OAM+1 mode purity of 94%. We proceed to show simulated and experimental C-band transmission spectra, with sufficient modulation depths confirmed experimentally at wavelengths of 1550nm and 15615nm.
Two-dimensional (2D) transverse eigenmodes were a standard method for analyzing structured light. buy Bay K 8644 Three-dimensional geometric light modes, synthesized as coherent superpositions of eigenmodes, have yielded new topological indices enabling light manipulation. Coupling optical vortices onto multiaxial geometric rays, while feasible, remains constrained by the azimuthal vortex charge. Within this work, a new structured light family, multiaxial super-geometric modes, is presented. These modes fully integrate radial and azimuthal indices with multiaxial rays, and their origin lies directly in the laser cavity. We experimentally confirm the multifaceted adjustability of complex orbital angular momentum and SU(2) geometrical configurations, exceeding the scope of prior multiaxial geometric modes. This capability, achievable through combined intra- and extra-cavity astigmatic mode conversion, has the potential to revolutionize optical trapping, manufacturing, and communications.
Investigations into all-group-IV SiGeSn lasers have established a novel path toward silicon-based light sources. In the past several years, the successful functioning of SiGeSn heterostructure and quantum well lasers has been observed. Multiple quantum well lasers' net modal gain is said to be influenced substantially by the optical confinement factor. Prior research suggested that incorporating a cap layer would enhance optical mode overlap with the active region, thus boosting the optical confinement factor within Fabry-Perot cavity lasers. Employing a chemical vapor deposition process, this work details the fabrication and optical pumping characterization of SiGeSn/GeSn multiple quantum well (4-well) devices, each with distinct cap layer thicknesses including 0, 190, 250, and 290nm. Spontaneous emission is evident only in devices with no cap or a thin cap, whereas thicker-cap devices exhibit lasing up to 77 Kelvin, exhibiting an emission peak at 2440 nanometers and a threshold of 214 kilowatts per square centimeter (250 nanometer cap device). This study's findings on device performance clearly delineate a path for designing electrically pumped SiGeSn quantum well lasers.
An anti-resonant hollow-core fiber supporting the LP11 mode with high purity and over a broad wavelength range is conceived and showcased in this work. To quash the fundamental mode, the resonant coupling with a particular gas is utilized, selectively filling the cladding tubes. A 27-meter-long fabricated fiber displays a mode extinction ratio exceeding 40dB at a wavelength of 1550nm and consistently above 30dB within a 150nm wavelength spectrum.