Observation of Interaction of Spin and Intrinsic Orbital Angular Momentum of Light

Interaction of spin and intrinsic orbital angular momentum of light is observed, as evidenced by length-dependent rotations of both spatial patterns and optical polarization in a cylindrically-symmetric isotropic optical fiber. Such rotations occur in straight few-mode fiber when superpositions of two modes with parallel and anti-parallel orientation of spin and intrinsic orbital angular momentum (IOAM=$2\hslash$) are excited, resulting from a degeneracy splitting of the propagation constants of the modes.Comment: 6 pages, 5 figures, and a detailed supplement. Version 3 corrects a typo and adds the journal referenc

Tunable SNAP Microresonators via Internal Ohmic Heating

We demonstrate a thermally tunable Surface Nanoscale Axial Photonics (SNAP) platform. Stable tuning is achieved by heating a SNAP structure fabricated on the surface of a silica capillary with a metal wire positioned inside. Heating a SNAP microresonator with a uniform wire introduces uniform variation of its effective radius which results in constant shift of its resonance wavelengths. Heating with a nonuniform wire allows local nanoscale variation of the capillary effective radius, which enables differential tuning of the spectrum of SNAP structures as well as creation of temporary SNAP microresonators that exist only when current is applied. As an example, we fabricate two bottle microresonators coupled to each other and demonstrate differential tuning of their resonance wavelengths into and out of degeneracy with precision better than 0.2 pm. The developed approach is beneficial for ultraprecise fabrication of tunable ultralow loss parity-time symmetric, optomechanical, and cavity QED devices

Entanglement swapping for generation of heralded time-frequency-entangled photon pairs

Photonic time-frequency entanglement is a promising resource for quantum information processing technologies. We investigate swapping of continuous-variable entanglement in the time-frequency degree of freedom using three-wave mixing in the low-gain regime with the aim of producing heralded biphoton states with high purity and low multi-pair probability. Heralding is achieved by combining one photon from each of two biphoton sources via sum-frequency generation to create a herald photon. We present a realistic model with pulsed pumps, investigate the effects of resolving the frequency of the herald photon, and find that frequency-resolving measurement of the herald photon is necessary to produce high-purity biphotons. We also find a trade-off between the rate of successful entanglement swapping and both the purity and quantified entanglement resource (negativity) of the heralded biphoton state.Comment: 17 pages and 9 figures. Version 3 corrects an error in the count rate theory and calculations, fixes a few grammatical and typographical errors, improves formatting, and adds the journal referenc

Coupling between waveguides and microresonators:The local approach

Coupling between optical microresonators and waveguides is a critical characteristic of resonant photonic devices that has complex behavior that is not well understood. When the characteristic variation length of the microresonator modes is much larger than the waveguide width, local coupling parameters emerge that are independent of the resonator mode distributions and offer a simplified description of coupling behavior. We develop a robust numerical-fitting-based methodology for experimental determination of the local coupling parameters in all coupling regimes and demonstrate their characterization along a microfiber waveguide coupled to an elongated bottle microresonator

Interferometric Photonic Crystal Modulators with Lithium Niobate

We demonstrate a photonic crystal cavity interferometric modulator in thin-film lithium niobate on insulator with 6 GHz bandwidth, 35 dB extinction, 2π ×1.27 GHz/V DC-tuning, and a 40-by-200 micron square footprint