Coupling nonlinear optical waves to photoreactive and phase-separating soft matter: Current status and perspectives

Abstract

Nonlinear optics and polymer systems are distinct fields that have been studied for decades. These two fields intersect with the observation of nonlinear wave propagation in photoreactive polymer systems. This has led to studies on the nonlinear dynamics of transmitted light in polymer media, particularly for optical self-trapping and optical modulation instability. The irreversibility of polymerization leads to permanent capture of nonlinear optical patterns in the polymer structure, which is a new synthetic route to complex structured soft materials. Over time more intricate polymer systems are employed, whereby nonlinear optical dynamics can couple to nonlinear chemical dynamics, opening opportunities for self-organization. This paper discusses the work to date on nonlinear optical pattern formation processes in polymers. A brief overview of nonlinear optical phenomenon is provided to set the stage for understanding their effects. We review the accomplishments of the field on studying nonlinear waveform propagation in photopolymerizable systems, then discuss our most recent progress in coupling nonlinear optical pattern formation to polymer blends and phase separation. To this end, perspectives on future directions and areas of sustained inquiry are provided. This review highlights the significant opportunity in exploiting nonlinear optical pattern formation in soft matter for the discovery of new light-directed and light-stimulated materials phenomenon, and in turn, soft matter provides a platform by which new nonlinear optical phenomenon may be discovered.

Opto-chemo-mechanical transduction in photoresponsive gels elicits switchable self-trapped beams with remote interactions

“…Our theoretical model provides valuable mechanistic insight into these interactions, by coupling photoisomerization to osmotic-pressure-driven contraction of the gel. In conventional nonlinear materials (1)(2)(3)(4)(16)(17)(18)(19), self-trapping suffers from one or more of the following disadvantages: 1) the need for large incident beam powers (∼watt) (19), 2) presence of an external field (16,17), 3) loss of beam interactions at distances beyond the overlap of their electromagnetic fields (2, 13), and 4) it is slow and irreversible (11,45). In contrast, the presented materials system demonstrates highly efficient selftrapping 1) at small, easily accessible (∼milliwatt) beam powers, 2) under ambient conditions; it is 3) rapid (∼50 s), 4) fully reversible at relatively fast timescales (∼100 s), and shows 5) sustained repeatability over multiple cycles (at least ∼50) and 6) almost instantaneous beam interactions for separation distances up to 10 beam widths.…”

“…Furthermore, this opto-chemo-mechanical transduction of energy mediated by the 3D cross-linked hydrogel network facilitates pairwise interactions between self-trapped beams both in the short range where there is significant overlap of their optical fields, and even in the long range--over separation distances of up to 10 times the beam width--where such overlap is negligible. dynamic optics | photochromic gels | self-trapped beams | nonlinear dynamics | spiropyran S elf-trapped light beams and spatial solitons emerge in a rich variety of photoresponsive materials that display intensitydependent changes in refractive index (1)(2)(3)(4). These nonlinear waves propagate without diverging through self-inscribed waveguides and exhibit intriguingly particlelike interactions such as collisions (5), fusion and birth (6), annihilation (7), and spiraling (8), typically in the short range (where there is significant overlap in their optical fields) and in rare cases, over long distances (where overlap is negligible and beams are remote) (9,10).…”

Solvent-Dependent Light-Induced Structures in Gem-Dichlorocyclopropanated Polybutadiene Solutions

“…This is reminiscent of some photoreactive systems. 18 There, a phenomenological nonlinear optical model was developed that captures well the time evolution of the pattern. It solved coupled equations, an evolution equation for the time/intensity dependent on the refractive index, and a nonlinear Schrodinger equation for light propagation.…”

“…The solutions can be obtained numerically. 18 Such a phenomenological modeling would certainly be useful in our case. It may help to understand the observed behavior.…”

“…17−19 It is conceivable that light-induced matter deformation can activate the mechanophore action in the absence of external mechanical stress. In fully transparent viscoelastic polydiene solutions, a peculiar light effect not conforming to known types of electrostriction 11,18 led to matter association along the laser beam. 20−24 The study of this effect has shown clearly the important role of the microstructure on the patterning efficiency and, in particular, the crucial role of 1,4-dienes.…”