Butt Leonard (canvaspyjama1)

We show that it can achieve the same functionality but with substantial speed and can operate in extremely low light conditions. This makes an event-based Shack-Hartmann wavefront sensor a preferable choice for adaptive optics systems where light budget is limited or high bandwidth is required.We present a design and fabrication approach for 3D printed polymer microstructured optical fiber tapers on standard single-mode glass fibers for efficient and compact mode-field conversion. This paves the way towards complex functionalized fiber tips for various applications, like sensors and beam shaping components, currently limited by the mode-field size and distribution of standard optical fibers. In this paper, we demonstrate the potential of mode-field converting tapers for relaxing the misalignment tolerance in fiber-to-fiber connections and maximizing the coupling efficiency in fiber-to-chip connections. We demonstrate a mode-field diameter expansion ratio of 1.7 and reduction ratio of 3 and show that our microstructured tapers achieve a comparable performance in coupling efficiency as their step-index counterparts, while providing greater robustness.Computationally modeling the behavior of wavelength-sized non-spherical particles in optical tweezers can give insight into the existence and stability of trapping equilibria as well as the optical manipulation of such particles more broadly. Here, we report Brownian dynamics simulations of non-spherical particles that account for detailed optical, hydrodynamic, and thermal interactions. We use a T-matrix formalism to calculate the optical forces and torques exerted by focused laser beams on clusters of wavelength-sized spheres, and we incorporate detailed diffusion tensors that capture the anisotropic Brownian motion of the clusters. For two-sphere clusters whose size is comparable to or larger than the wavelength, we observe photokinetic effects in elliptically-polarized beams. We also demonstrate that multiple trapping equilibria exist for a highly asymmetric chiral cluster of seven spheres. Our simulations may lead to practical suggestions for optical trapping and manipulation as well as a deeper understanding of the underlying physics.We present two sets of versatile high-numerical-apeture objectives suitable for various cold-atom experiments. The objectives are assembled entirely by the commercial on-shelf singlets. The two objectives are initially optimized at working wavelength of 852 nm with a standard 5-mm silica optical flat window. They have numerical apertures of NA=0.55 and NA=0.78, working distances of 23 and 12.8 mm, diffraction-limited fields of view of 98 and 15 μm, and spatial resolutions of 0.94 and 0.67 μm, respectively. These performances are simulated by the ray-tracing software and experimentally confirmed by imaging line patterns and a point-like emitter on a resolution chart. The two objectives can be further reoptimized at any single wavelengths from ultraviolet to near infrared and for various optical flat window with different thickness by only tuning one of lens spacing. The two objectives provide convenient and flexible options to observe and address individual atoms in single atom arrays or optical lattices for various cold-atom experiments.Subwavelength-scale surface structures have many important engineering and nanotechnology applications, e.g., superhydrophobicity and light-trapping. However, an effective and economic nanofabrication solution for general engineering materials, e.g., metals or silicon, is still not available to date. In this paper, we present an experimental and theoretical study of the nanostructure formation mechanism based on double time-delayed femtosecond laser beams and the coupled mode theory (CMT), demonstrating the use of an optical analogue of massless Dirac particles for high-throughput nanofabrication for the first time. In the experiments, a variety of complex periodic structures, including hexagonally arranged nanoh