Optics InfoBase is the Optical Society's online library for flagship journals, partnered and copublished journals, and recent proceedings from OSA conferences.

Degeneracies play a crucial rule in precise scientific measurements as well as in sensing applications. Spherical resonators have a high degree of degeneracy thanks to their highest symmetry; yet, fabricating perfect spheres is challenging because even a stem to hold the sphere breaks the symmetry. Here we fabricate a levitating spherical resonator that is evanescently coupled to a standard optical fiber. We characterize the resonators to exhibit an optical quality factor exceeding a billion, $10\mu \mathrm{m}$ radius, and sphericity to within less than 1 Å. Using our high quality and sphericity, we experimentally lift degeneracies of orders higher than 200, which we resolve with optical finesse exceeding 10 000 000. We then present our experimentally measured degenerate modes as well as their density of states next to our corresponding theoretical calculation. Our contactless photonic resonator is compatible with standard telecom fiber technology, exhibits the highest resonance enhancement as defined by (quality factor)/(mode volume), and the modes populating our cavity show the highest order of degeneracy reported in any system ever studied. This is in comparison with other settings that typically utilize the lowest-order twofold degeneracy.

We report a microfluidic droplet generator which can produce single and compound droplets using a 3D axisymmetric co-flow structure. The design considered for the fabrication of the device integrated a user-friendly and cost-effective 3D printing process. To verify the performance of the device, single and compound emulsions of deionized water and mineral oil were generated and their features such as size, generation frequency, and emulsion structures were successfully characterized. In addition, the generation of bio emulsions such as alginate and collagen aqueous droplets in mineral oil was demonstrated in this study. Overall, the monolithic 3D printed axisymmetric droplet generator could offer any user an accessible and easy-to-utilize device for the generation of single and compound emulsions.

Optical tweezers can rapidly manipulate dielectric objects for applications ranging from microcentrifuges to controlling droplets and particles in a “lab-in-air” configuration. Here, we uniquely combine light propagation that is predominantly parallel to the particle’s orbital track—rather than primarily perpendicular as in conventional vortices—with operation in air. We measure a 7-micrometer sphere circulating at 20,400 rounds per minute [340 hertz (Hz)] along 120-micrometer circumference tracks, achieving accelerations up to 10 times that of gravity (98 square meters per second). Our trap’s optical orbital angular momentum of ℓ = 242ℏ per photon, combined with the gaseous environment, enables high circulation frequencies and underdamped operation at a high mechanical quality factor, Q . Together, our Q - f product of 5300 Hz facilitates low dissipation in combination with rapid particle manipulation. This advancement could substantially expand the impact of dynamic optical traps, particularly in fundamental measurements.