Micronewton nanofiber force sensor using Brillouin scattering.

We present a new class of force sensor based on Brillouin scattering in an optical nanofiber. The sensor is a silica nanofiber of a few centimeters with a submicron transverse dimension. This extreme form factor enables one to measure forces ranging from 10 μN to 0.

Local activation of surface and hybrid acoustic waves in optical microwires.

Elastic vibrations in subwavelength structures have gained importance recently in fundamental light-matter studies and various optoacoustic applications. Existing techniques have revealed the presence of distinct acoustic resonances inside silica microwires yet remain unable to individually localize them. Here, we locally activate distinct classes of acoustic resonances inside a tapered fiber using a phase-correlation distributed Brillouin method.

Surface Brillouin scattering in photonic crystal fibers.

We report, to the best of our knowledge, the first experimental observation of surface Brillouin scattering in silica-based photonic crystal fibers, arising from the interaction between guided light and surface acoustic waves. This was achieved using small-core and high air-filling fraction microstructured fibers that enable a strong opto-acoustic coupling near the air holes while mitigating the acoustic leakages in the microstructured cladding. It is further shown that this new type of light scattering is highly sensitive to the fiber air-hole microstructure, thus providing a passive and efficient way to control it.

Light coupling with a nonlinear prism.

We propose the use of a prism with nonlinear optical properties to improve the prism-coupling method. The principle is based on the inscription of an adapted waveguide inside this prism by beam self-trapping to enhance the coupling efficiency and stability. The experimental demonstration is realized with a prism diced from a LiNbO3 wafer to couple light into a resonator.

Silicon-on-insulator integrated source of polarization-entangled photons.

We report the experimental generation of polarization-entangled photons at telecommunication wavelengths using spontaneous four-wave mixing in silicon-on-insulator wire waveguides. The key component is a 2D coupler that transforms path entanglement into polarization entanglement at the output of the device. Using quantum state tomography we find that the produced state has fidelity 88% with a pure nonmaximally entangled state.