This study focuses on the photomechanical behavior of step-index optical fibers with a polydimethylsiloxane (PDMS) core and fluoropolymer claddings. The PDMS hosts dopant graphene nanoplatelets, which are heated when illuminated by visible light. Sample fibers were fabricated by drawing the doped resin into thin fluoropolymer tubing before the resin set. The individual motions of the core and cladding were observed to be coupled, which resulted in a relatively small photomechanical effect. Adding a castor oil lubricant between the core and cladding significantly increased the core’s photomechanical strain. The large strain of the lubricated cores exhibited both irreversible and reversible photomechanical motion. Cycling the pump beam resulted in a fully reversible photomechanical piston that can be modeled by a linear response function to the incident pump beam.
We discuss some optical properties of cellulose nanocrystals decorated with silver nanospheres. We give a short description of the discrete dipole interactions, and the broadening effects observed in the extinction spectrum. We also discuss some preliminary results for their use in organic photovoltaic devices.
We report on time-of-flight (TOF) hole mobility measurements in an aged discotic columnar liquid crystal, Hexakis(pentyloxy)triphenylene (HAT5). The experimental data was fit to an interfacial trapping model based on Van de Walle’s approximations. The theory accurately reproduces the TOF transients of delayed charge release near the optically excited material/electrode interface. Interfacial trapping appears only in the aged materials, but the bulk mobility is the same as that of the pristine material. We also discuss preliminary results of TOF photocurrent transients of HAT5 exposed to ozone.
We study the effects of temperature changes on the operating wavelength of all-polymer microresonator lasers, particularly on multilayered defect distributed feedback and distributed Bragg reflector lasers. The parameters that change the operating wavelength are discussed with comparisons between experiments and simulations.
Sum rules are used to develop a broad understanding of light-matter interactions through investigations of
universal properties and are applied to specific phenomena to gain insights into the underlying fundamental
processes. We discuss universal properties associated with the third-order nonlinear-optical response and show
how microscopic cascading – where two molecules interact through their hyperpolarizabilities to yield a second
hyperpolarizability – must obey these same universal properties. In addition, we discuss how the sum rules imply
more exotic classes of Hamiltonians and their consistency with physical laws, which may partially explain the
difference between the sum-rule-derived fundamental limits and observations.
We review a model that was developed to take into account all possible microscopic cascading schemes in a single
species system out to the fifth order using a self-consistent field approach. This model was designed to study the
effects of boundaries in mesoscopic systems with constrained boundaries. These geometric constraints on the
macroscopic structure show how the higher-ordered susceptibilities are manipulated by increasing the surface to
volume ratio, while the microscopic structure influences the local field from all other molecules in the system.
In addition to the review, we discuss methods of modeling real systems of molecules, where efforts are currently
underway.
Azobenzene dye-doped liquid crystal elastomers (LCE) are known to give strong photomechanical responses. We
review photothermal heating actuated Photomechanical Optical Devices (PODs) and applications to systems by
examining successful attempts at cascading macroscopic PODs in a series configuration. Using these results, we
present some new design strategies that have the potential of miniaturizing these systems with increases in the
response time and system integration.
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