By exploiting the nanometer sensitivity of the confocal response to the position of an in-focus reflecting surface, we measured the bending rigidity of lipid-bilayer vesicles with a noninvasive all-optical method. The vesicles were weakly deformed with femtonewton optical force, and the bending rigidity was measured continuously from the $L_{\alpha }$ through the $P_{{\beta }^{\prime }}$ to the $L_{{\beta }^{\prime }}$ phases on the same specimen for the first time. The bending modulus is found to increase by an order of magnitude from the $L_{\alpha }$ phase to the $L_{{\beta }^{\prime }}$ phase, as a result of the increasing area-compressibility modulus and bilayer thickness. The dips of bending modulus give precisely the main-transition and pretransition temperatures, which supports the recently proposed chain-melting model of pretransition.

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Enhancement of relativistic third-harmonic generation by using an optically preformed periodic plasma waveguide was achieved. Resonant dependence of harmonic intensity on plasma density and density modulation parameters was observed, which is a distinct characteristic of quasi-phase-matching. The results demonstrate the potential of a modulated plasma waveguide in high-field applications.

By using a laser-induced transient density ramp, we demonstrate self-injection of electrons in a self-modulated laser-wakefield accelerator with spatial localization. The number of injected electrons reaches $1.7\times {10}^8$. The transient density ramp is produced by a prepulse propagating transversely to drill a density depression channel via ionization and expansion. The same mechanism of injection with comparable efficiency is also demonstrated with a transverse plasma waveguide driven by Coulomb explosion.