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2 to 5.4 dB insertion loss to drop ports.Being the established imaging tool for cell membrane-associated studies, total internal reflection fluorescence microscopy (TIRFM) still has some limitations. The most important one is the inhomogeneous evanescent excitation field mainly caused by the large-angle and fixed-azimuth illumination scheme, which can be eliminated by using ring-shaped illumination (ring TIRFM). However, it is challenging in assembling a ring TIRFM system with precise parameter control that works well. Here we emphasize the quantification of the ring TIRFM system and introduce a robust calibration routine to simultaneously rectify the asymmetry of the spinning light beam and determine the crucial experimental parameter, i.e., the incident angle. The calibration routine requires no specific sample preparation and is entirely based on the automatic back focal plane manipulation, avoiding possible errors caused by the sample difference and manual measurement. Its effectiveness is experimentally demonstrated by both the qualitative and quantitative comparisons of the images acquired using different samples, illumination schemes, and calibration approaches. These characteristics should enable our approach to greatly improve the practicability of TIRFM in life sciences.Directional couplers are extensively used in photonic integrated circuits as basic components for efficient on-chip photonic signal routing. Conventionally, directional couplers are fully encapsulated in the technology's waveguide cladding material. In this Letter, we demonstrate a compact broadband directional coupler, fully suspended in air and exhibiting efficient power coupling in the cross state. The coupler is designed and built based on IMEC's iSiPP50G standard platform, and hydrofluoric (HF) vapor-etching-based post-processing allows to release the freestanding component. A low insertion loss of 0.5 dB at λ=1560nm and a 1 dB bandwidth of 35 nm at λ=1550nm have been confirmed experimentally. With a small footprint of 20µm×30µm and high mechanical stability, this directional coupler can serve as a basic building block for large-scale silicon photonic microelectromechanical systems (MEMS) circuits.In this Letter, a hybrid frequency-time spectrograph combining a tunable optical filter and a dispersive element is presented for measurement of the spectral properties of the two-photon state. In comparison with the previous single-photon spectrograph utilizing the dispersive Fourier transformation (DFT) technique, this method is advanced since it avoids the need for additional wavelength calibration and the electronic laser trigger for coincidence measurement; therefore, its application is extended to continuous wave (CW) pumped two-photon sources. The achievable precision of the spectrum measurement has also been discussed in theory and demonstrated experimentally with a CW pumped periodically poled lithium niobate (PPLN) waveguide-based spontaneous parametric down-conversion photon source. Such a device is expected to be a versatile tool for the characterization of the frequency entangled two-photon state.Metal surfaces with low reflectance have received considerable attention for their great optical, electrical, and thermal properties. However, the difficulty in achieving low reflectance on curved metal surfaces has hindered their practical applications. We propose a rapid and flexible method for processing a three-dimensional surface with antireflective properties. A Bessel beam created using an axicon is employed to generate ripple structures on the curved surface, thereby assisting subsequent thermal oxidation. Ripple structures coated with oxide semiconductor nanowires are then processed on a Cu substrate, thus further reducing reflectance. Antireflective properties with a minimum reflectance of less than 0.015 at a wavelength of 500-1200 nm could be achieved by using this method. This presented approach reduces dimensionality in laser processing, subsequently improving processing efficiency, and provides a foundation for the practical application of metal antireflective surfaces.Accurate dispersion management is key for efficient nonlinear light generation. Here, we demonstrate that composite-liquid-core fibers-fibers with binary liquid mixtures as the core medium-allow for accurate and tunable control of dispersion, loss, and nonlinearity. selleck chemicals Specifically, we show numerically that mixtures of organic and inorganic solvents in silica capillaries yield anomalous dispersion and reasonable nonlinearity at telecommunication wavelengths. This favorable operation domain is experimentally verified in various liquid systems through dispersion-sensitive supercontinuum generation, with all results being consistent with theoretical designs and simulations. Our results confirm that mixtures introduce a cost-effective means for liquid-core fiber design that allows for loss control, nonlinear response variation, and dispersion engineering.Most microsphere-assisted super-resolution imaging experiments require a high-refractive-index microsphere to be immersed in a liquid to improve the super-resolution. However, samples are inevitably polluted by residuals in the liquid. This Letter presents a novel (to the best of our knowledge) method employing a microsphere lens group (MLG) that can easily achieve high-quality super-resolution imaging in air. The performance of this method is at par or better than that of the high-refractive-index microspheres immersed in liquid. In addition, the MLG generates a real image that is closely related to the photonic nanojet position of the microsphere super-lens. This imaging method is beneficial in microsphere imaging applications where liquids are impractical.In this Letter, we propose a new configuration for visible light communication systems, which results in doubling of the data rate due to the use of polarization division multiplexing. As light-emitting diodes are unpolarized incoherent light sources, we isolate both the perpendicular s and parallel p modes for independent modulation. For the first time, to the best of our knowledge, we show that it is possible to transmit and successfully recover two separate orthogonal frequency division multiplexing (OFDM) signals on each polarization (pol-OFDM). Furthermore, we compare the performance of the pol-OFDM system with the transmission of a single conventional OFDM signal without a polarizer over the same physical link. We show that similar bit error rates can be achieved while obtaining ∼45% improvement in both the data rate and spectral efficiency due to polarization multiplexing.