Typical methods to decode a complex orbital-angular-momentum (OAM) spectrum suffer from issues such as a narrow OAM range, unstable interferometer, and long measuring time. In this Letter, we use a single-beam interferometer to measure the complex OAM spectrum with a single-pixel detector. The complex OAM spectrum ranging from -10 to 10 can be measured in 11 ms with the fidelity approach of 97.0%, experimentally. Our approach allows one to characterize an unknown coherent field with any complex basis, e.g., the Laguerre-Gaussian (LG) basis is used for radial index spectrum measurement. Furthermore, single-pixel complex amplitude imaging based on the LG spectrum acquisition is presented, and the advantages in resolution and flexibility are demonstrated.It is a daunting challenge to realize ultraviolet C (UVC) lasing (i.e., has a wavelength range from 200 to 275 nm) from upconversion nanocrystals due to their low upconversion efficiency. Here, we fabricate Ba2LaF7Yb3+(90mol%), Tm3+(5mol%) upconversion nanocrystals from amorphous borosilicate glass to support emission at ∼263nm under 980 nm ns laser excitation. The excitation threshold can be further reduced from ∼130 to ∼26.5mJ/cm2 by using a cylindrical microcavity. We also found that the growth of defect-free Ba2LaF7 nanocrystals with a high concentration of codoping Yb3+ and Tm3+ ions inside high optical damage threshold borosilicate glass is the key to achieving room-temperature UVC upconversion lasing under high-intensity excitation.We present a scheme for correction of x-y-separable aberrations in optical coherence tomography (OCT) designed to work with phase unstable systems with no hardware modifications. Our approach, termed SHARP, is based on computational adaptive optics and numerical phase correction and follows from the fact that local phase stability is sufficient for the deconvolution of optical aberrations. We demonstrate its applicability in a raster-scan polygon-laser OCT system with strong phase-jitter noise, achieving successful refocusing at depths up to 4 times the Rayleigh range. https://www.selleckchem.com/products/tocilizumab.html We also present in vivo endoscopic and ex vivo anterior segment OCT data, showing significant enhancement of image quality, particularly when combining SHARP results with a resolution-preserving despeckling technique like TNode.Polydimethylsiloxane-based optofluidics provides a powerful platform for a complete analytical lab-on-chip. Here, we report on a novel on-chip laser source that can be integrated with sample preparation and analysis functions. A corrugated sidewall structure is integrated into a microfluidic channel to form a distributed feedback (DFB) laser using rhodamine 6G dissolved in an ethylene glycol and water solution. Lasing is demonstrated with a threshold pump power of 87.9 µW, corresponding to a pump intensity of 52.7mW/cm2. Laser threshold and output power are optimized with respect to rhodamine 6G concentration and core index and found to be in good agreement with a rate equation model. Additionally, the laser can be switched on and off mechanically using a pneumatic cell inducing positive pressure on the grating.We report on the first, to the best of our knowledge, frequency ratio measurement of an 115In+ singleion clock and a 87Sr optical lattice clock. A hydrogen maser serves as a flywheel oscillator to measure the ratio by independent optical combs. From 89,000 s of measurement time, the frequency ratio f I n /f S r is determined to be 2.952 748 749 874 863 3(23) with 7.7×10-16 relative uncertainty. The measurement creates a new connection in the network of frequency ratios of optical clocks.The converged vortex beam with a well-defined focal plane is an essential ingredient for trapping and rotating microparticles. Metasurfaces, two-dimensional metamaterials, provide an ultra-compact and flexible platform for designing a converged vortex by integrating the functions of a lens and vortex plate. A spin-defocused metasurface can further boost information capacity such as the multiplexing of helicity-dependent functionalities. Here we propose an approach to realize spin-defocused metalenses that can simultaneously focus terahertz (THz) waves with orthogonal spin states into helicity-dependent vortices based on pure geometric phases. Under the illumination of linearly polarized terahertz waves, all of the helicity-dependent vortices are observed, leading to helicity-multiplexing of converged vortices. Furthermore, the longitudinal multiplexing of converged cylindrical vector beams is demonstrated by superposition of helicity-dependent vortices. This unique approach for multiplexing converged vortices and cylindrical vector beams may open a window for designing future ultra-compact and multifunctional devices with potential applications in communications, optical trapping, and focusing.Fast Fourier transform (FFT) is the most commonly used mathematical method in numerical calculation, and the FFT-based angular spectrum method (ASM) is also used widely in diffraction calculation. However, the frequency and spatial sampling rules in FFT limit the effective propagation distance and the observation window range of ASM. A novel method for calculating the angular spectrum based on the matrix product is proposed in this Letter. This method realizes the fast calculation of discrete Fourier transform (DFT) based on the matrix product, in which the sampling matrix is orthogonally decomposed into two vectors. Instead of FFT, angular spectrum diffraction calculation is carried out based on the matrix product, which is named the matrix product ASM. The method in this Letter uses a simple mathematical transformation to achieve maximum compression of the sampling interval in the frequency domain, which significantly increases the effective propagation distance of the angular spectrum. Additionally, the size of the observation window can be enlarged to obtain a wider calculation range by changing the spatial sampling of the output plane.The implementation of a polarization beam splitter (PBS) on a silicon nitride platform remains challenging owing to its relatively low index. We therefore propose a silicon nitride PBS that exploits serially cascaded asymmetric directional couplers (ADCs), leading to a high polarization extinction ratio (PER) over a broad bandwidth. The ADC spatially routes incident light through polarization-selective mode coupling under a small footprint of 112 µm. The proposed PBS does not require an active phase control. It is thus effectively realized via a single-step lithography process. The measured transverse-electric and transverse-magnetic PERs were determined to be above 23 dB and 10 dB over an 80-nm bandwidth, respectively, spanning λ=1520-1600nm. The proposed device is thus anticipated to play a key role in providing polarization diversity in photonic-integrated circuits.