Fabrication and characterization of a diffraction-grating transducer in thin polybutadiene rubber film for sensing dynamical strain.

Surface relief gratings are holographically fabricated in thin polybutadiene rubber films produced by both spin coating and dip coating on glass and metal substrates. These thin-film gratings are characterized for their application as efficient transducers for detecting dynamic strain in solids. The performance of these rubber-grating transducers is compared to surface-mounted fiber Bragg gratings for a range of frequencies between 50 Hz and 30 kHz.

Photoinduced grating formation in azo-dye-labeled phospholipid thin films by 244-nm light.

Holographic gratings are recorded in azo-dye nitrobenzoxazole-labeled phospholipid thin films by use of 244-nm UV light. The gratings continue to grow for more than 1 h, even after the recording light is removed. The diffraction efficiency of these gratings shows extreme sensitivity to humidity and can increase reversibly by 2 orders of magnitude in air that is saturated with water vapor.

Four-photon-mixing-mediated stimulated Raman scattering in a multimode optical fiber.

Stimulated Raman scattering with 532-nm pulsed laser light is investigated in a 7.9-microm-core step-index multimode fiber. While low-intensity pump or single-mode LP(01) excitation produces the usual stimulated Raman scattering light, mixed-mode (LP(01) + LP(02)) excitation with pump intensities of ~5 kW uniformly shifts the multiorder Stokes Raman spectrum by an amount determined by fiber parameters, thus making stimulated Raman scattering tunable.