A New Opto-Mechanical Effect in Solids

Abstract

We propose that large, reversible shape changes in solids, of between 10%-400%, can be induced optically by photoisomerizing monodomain nematic elastomers. Empirical and molecular analysis of shape change and its relation to thermal effects is given along with a simple model of the dynamics of response. Our experiments demonstrate these effects for the first time and theory is compared qualitatively with our results.

Bleaching and stimulated recovery of dyes and of photocantilevers

“…These estimates for α are lower bounds on actual values; including the effects of attenuation through the cantilever will lead to higher values of α. In later work [5] one can deduce that α ∼ 0.8. The divergence of the Poynting flux, ∂I ∂x , at any point through the cantilever is equal to the amount of energy taken out of the beam per unit volume per unit time.…”

“…We shall take η = 1 in the numerical illustrations in this paper. We have ignored any attenuation by the host material; one could include such effects by adding a simple Lambert-Beer term −I(x, t)/d h to the RHS of eqn (4) or eqn (5).See section III A for an analysis.…”

“…Smaller changes arise in glasses, where subtle arrangements of director have been employed to achieve more complex mechanical responses [2]. Since light and heat have analogous effects, one expects and indeed finds that optical absorption leads to analogous mechanical strains, both in photo-elastomers [5,6] and in photo-glasses [7]. Such a mechanism of mechanical change offers the possibility of micro-opto-mechanical systems (MOMS) where elements can be optically-induced to bend as elastomeric photo-swimmers [8] or as glassy cantilevers [7,9,10].…”

Photo‐Crosslinked Side‐Chain Liquid‐Crystalline Elastomers for Microsystems

“…The potential of these materials makes them interesting for microengineering, where their integration can induce the movement of a reduced volume engine. Temperature, [1] voltage, [2] or light [3,4] are driving forces than can produce such movements by inducing change of order in the liquid-crystalline structure.…”

Effects of structural imperfections on the dynamic mechanical response of main‐chain smectic elastomers

“…LCE therefore exhibit strong deviations from ordinary rubber elasticity, leading to striking physical phenomena such as the polydomain-to-monodomain (P-M) transition [3][4][5][6][7] and the shape changes and director reorientations observed in globally oriented ''monodomain'' samples. [8][9][10][11][12][13][14][15][16][17][18][19][20] The physical factors governing the dynamic mechanical response of LCE are of primary fundamental interest, as it is exceptional mechanical behavior that distinguishes LCE from all other elastomers.…”