Direct measurement of optical-trap-induced decoherence

Diffusion-induced decoherence of stored optical vortices

We study the coherence properties of optical vortices stored in atomic ensembles. In the presence of thermal diffusion, the topological nature of stored optical vortices is found not to guarantee slow decoherence. Instead the stored vortex state’s decoherence is surprisingly larger than the stored Gaussian mode. Furthermore, calculation of the coherence factor shows that the center of the store...

Direct measurement of the oscillation frequency in an optical-tweezers trap by parametric excitation.

We demonstrate a novel technique for direct measurement of the oscillation frequency in an optical-tweezers trap. The technique uses the phenomenon of parametric resonance in an oscillator when the stiffness of the trapping potential is modulated. The trapped particle is a strongly damped oscillator; hence, the signature of parametric resonance is not an increase in the amplitude but an increas...

Comment on "direct measurement of the oscillation frequency in an optical-tweezers trap by parametric excitation".

Direct measurement of force generation by actin filament polymerization using an optical trap.

Actin filament polymerization generates force for protrusion of the leading edge in motile cells. In protrusive structures, multiple actin filaments are arranged in cross-linked webs (as in lamellipodia or pseudopodia) or parallel bundles (as in filopodia). We have used an optical trap to directly measure the forces generated by elongation of a few parallel-growing actin filaments brought into ...

Raman Spectra of a PMMA Microstructured Optical Fibre and Direct Measurement of Its Gain Coefficient

 A polymethylmethacrylate (PMMA) microstructured polymer optical fiber (mPOF) is fabricated and characterized. Using the cut-back technique the fiber loss is measured which is higher than the step-index silica fibers. Through a novel experimental scheme, the backward Stokes spectrum of the fabricated mPOF is recorded over a range exceeding 3000 cm‑1 during the cut-back method and compared ...