We empirically demonstrate that Light Sheet Microscopy produces images showcasing the internal geometrical attributes of an object, some of which may not be captured by standard imaging methods.
High-capacity, interference-free communication links between low-Earth orbit (LEO) satellite constellations, spacecraft, and space stations and the Earth necessitate the use of free-space optical (FSO) systems. The incident beam's collected portion necessitates a coupling to an optical fiber for seamless integration with high-capacity ground networks. To assess the signal-to-noise ratio (SNR) and bit-error rate (BER) metrics precisely, one must ascertain the probability density function (PDF) of fiber coupling efficiency (CE). While prior research has empirically validated the cumulative distribution function (CDF) of the received signal for single-mode fibers, analogous studies concerning the cumulative distribution function of multi-mode fibers in low-Earth orbit (LEO) to ground free-space optical (FSO) downlinks remain absent. Using data from the Small Optical Link for International Space Station (SOLISS) terminal's FSO downlink to a 40-cm sub-aperture optical ground station (OGS) with a fine-tracking system, this paper provides, for the first time, an experimental analysis of the CE PDF for a 200-meter MMF. PF07321332 In spite of the non-optimal alignment between SOLISS and OGS, an average of 545 decibels in CE was still observed. Analysis of angle-of-arrival (AoA) and received power data provides insights into the statistical attributes, such as channel coherence time, power spectral density, spectrograms, and probability distribution functions of AoA, beam misalignments, and atmospheric turbulence effects, which are then compared with state-of-the-art theoretical foundations.
The fabrication of advanced, entirely solid-state LiDAR hinges upon the implementation of optical phased arrays (OPAs) boasting a vast field of view. Crucially, a wide-angle waveguide grating antenna is introduced in this work. Rather than aiming to eliminate the downward radiation of waveguide grating antennas (WGAs), we use this downward radiation to increase the beam steering range by two times. A common set of power splitters, phase shifters, and antennas facilitates steered beams in two directions, expanding the field of view while dramatically minimizing chip complexity and power consumption, notably in large-scale OPAs. Far-field beam interference and power fluctuations resulting from downward emission can be lessened through the application of a tailored SiO2/Si3N4 antireflection coating. The WGA's emissions are evenly distributed, both upwards and downwards, with a field of view exceeding 90 degrees in each direction. PF07321332 The normalized intensity demonstrates an almost consistent level, with only a 10% deviation, ranging from -39 to 39 for upward emission and -42 to 42 for downward emission. This WGA possesses a distinctive flat-top radiation pattern in the far field, remarkable for high emission efficiency and an ability to handle manufacturing errors effectively. The prospect of wide-angle optical phased arrays is promising.
GI-CT, an emerging imaging technique employing X-ray grating interferometry, offers three distinct contrasts—absorption, phase, and dark-field—with potential for enhancing diagnostic information in clinical breast CT applications. Recovering the three image channels within clinically appropriate conditions is challenging because of the substantial instability of the tomographic reconstruction procedure. This paper introduces a novel reconstruction algorithm based on a fixed correspondence between the absorption and phase-contrast channels to create a single, reconstructed image, accomplishing this by automatically merging the two channels. The results of both simulation and real-world data highlight GI-CT's superiority to conventional CT at clinical doses, enabled by the proposed algorithm.
Tomographic diffractive microscopy, or TDM, leveraging the scalar light-field approximation, is a widely used technique. Samples with anisotropic structures, however, necessitate the incorporation of light's vectorial characteristics, thereby necessitating 3-D quantitative polarimetric imaging. The construction and implementation of a high-numerical-aperture Jones time-division multiplexing system, leveraging a polarized array sensor (PAS) for detection multiplexing, are detailed in this work, enabling high-resolution imaging of optically birefringent samples. The initial stage of studying the method includes image simulations. To ascertain the correctness of our configuration, an experiment was conducted involving a sample which encompassed both birefringent and non-birefringent components. PF07321332 After extensive research, the Araneus diadematus spider silk fiber and Pinna nobilis oyster shell crystals have been investigated, enabling the analysis of both birefringence and fast-axis orientation maps.
In this work, we explore the properties of Rhodamine B-doped polymeric cylindrical microlasers, which can serve as either gain amplification devices via amplified spontaneous emission (ASE) or as optical lasing gain devices. Different weight percentages of microcavity families, each with unique geometrical attributes, were studied to understand the characteristic dependence on gain amplification phenomena. Principal component analysis (PCA) reveals the correlations between key aspects of amplified spontaneous emission (ASE) and lasing performance, and the geometrical features of different cavity designs. Cylindrical cavity microlasers demonstrated exceptionally low thresholds for both amplified spontaneous emission (ASE) and optical lasing, achieving values as low as 0.2 Jcm⁻² and 0.1 Jcm⁻², respectively, outperforming previously reported benchmarks, even those employing 2D cavity designs. Our microlasers, moreover, displayed an extremely high Q-factor of 3106. For the first time, to our knowledge, a visible emission comb, containing more than a hundred peaks at 40 Jcm-2, exhibited a registered free spectral range (FSR) of 0.25 nm, confirming the validity of the whispery gallery mode (WGM) theory.
The dewetting of SiGe nanoparticles has enabled their use for manipulating light in the visible and near-infrared spectrum, although the quantitative analysis of their scattering behavior is yet to be addressed. A SiGe-based nanoantenna under tilted illumination displays Mie resonances that emit radiation patterns with directional variability. This novel dark-field microscopy setup, by strategically shifting the nanoantenna below the objective lens, allows for the spectral separation of Mie resonance contributions to the total scattering cross-section during a single, unified measurement. The aspect ratio of islands is subsequently assessed using 3D, anisotropic phase-field simulations, thereby refining the interpretation of experimental findings.
Mode-locked fiber lasers, offering bidirectional wavelength tuning, are crucial for a wide array of applications. Our experiment produced two frequency combs from a single, bidirectional carbon nanotube mode-locked erbium-doped fiber laser. Employing a bidirectional ultrafast erbium-doped fiber laser, continuous wavelength tuning is demonstrated for the first time in this study. By leveraging the microfiber-assisted differential loss-control effect in both directions, we adjusted the operational wavelength, observing differing tuning capabilities in each direction. Stretching microfiber by 23 meters and applying strain allows for the tuning of the repetition rate difference, enabling a range from 986Hz to 32Hz. In parallel, a minor discrepancy of 45Hz was observed in the repetition rate. The potential for this technique lies in its ability to broaden the wavelength spectrum of dual-comb spectroscopy, consequently widening its areas of use.
From ophthalmology to laser cutting, astronomy, free-space communication, and microscopy, measuring and correcting wavefront aberrations is essential. This process is fundamentally reliant on measuring intensities to ascertain the phase. To recover the phase, the transport-of-intensity method is employed, capitalizing on the relationship between observed energy flow within optical fields and their wavefronts. This scheme, based on a digital micromirror device (DMD), provides a simple method for dynamically determining the wavefront of optical fields at various wavelengths with high resolution and adjustable sensitivity, while performing angular spectrum propagation. Our approach is evaluated by extracting common Zernike aberrations, turbulent phase screens, and lens phases under fluctuating and stable conditions, spanning multiple wavelengths and polarizations. Distortion correction in adaptive optics is facilitated by this configuration, utilizing a second DMD for conjugate phase modulation. Various conditions yielded effective wavefront recovery, facilitating convenient real-time adaptive correction in a compact design. Our approach develops an all-digital system that is flexible, cheap, rapid, precise, broadband, and unaffected by polarization.
A breakthrough in fiber optic design has led to the creation and successful demonstration of a large mode-area chalcogenide all-solid anti-resonant fiber for the first time. The numerical analysis indicates that the designed fiber exhibits a high-order mode extinction ratio of 6000, and a maximum mode area of 1500 square micrometers. Provided the bending radius of the fiber exceeds 15cm, a calculated bending loss of less than 10-2dB/m is observed. Furthermore, a low normal dispersion of -3 ps/nm/km at 5m is observed, which is advantageous for high-power mid-infrared laser transmission. Ultimately, a meticulously structured, entirely solid fiber was fabricated using the precision drilling and two-stage rod-in-tube procedures. The fabricated fibers' mid-infrared spectral range transmission spans from 45 to 75 meters, with the lowest observed loss being 7dB/m at the 48-meter mark. The optimized structure's theoretical loss, as modeled, aligns with the prepared structure's loss in the long wavelength region.