Enhanced photoinduced nematic reorientation in mixture with azo-dye-substituted polymer

Photoinduced split of the cavity mode in photonic crystals based on porous silicon filled with photochromic azobenzene-containing substances

The novel phototunable photonic structures based on electrochemically etched silicon filled with four photochromic azobenzene-containing compounds, bent-shaped low molar mass substance and side-chain polymethacrylates and copolyacrylate, were prepared and their photooptical properties were studied. It was found that irradiation of these composites with polarized blue light results in spectral changes in photonic band gap (split of the cavity mode) associated with cooperative photoorientation of azobenzene moieties inside silicon pores in direction perpendicular to the polarization plane of the…

Photoinduced modulation of refractive index in Langmuir-Blodgett films of Azo-based H-shaped liquid crystal molecules

The development of optically active area consisting of organic molecules are essential for the devices like optical switches and waveguides, as it can be easily maneuvered by the application of suitable electromagnetic (EM) waves. In this article, we report the development of a photoactive surface by the deposition of a single layer of Langmuir-Blodgett (LB) film of a novel H-shaped liquid crystal (HLC) molecule. The synthesized HLC molecules possess azo-groups and nitro-groups. The azo-group can be isomerized (trans-cis transformation) by irradiating them with ultraviolet (UV) light. The nitr…

Light-induced rotation of dye-doped liquid crystal droplets

We investigate both theoretically and experimentally the rotational dynamics of micrometric droplets of dye-doped and pure liquid crystal induced by circularly and elliptically polarized laser light. The droplets are dispersed in water and trapped in the focus of the laser beam. Since the optical torque acting on the molecular director is known to be strongly enhanced in light-absorbing dye-doped materials, the question arises whether a similar enhancement takes place also for the overall optical torque acting on the whole droplets. We searched for such enhancement by measuring and comparing t…

利用结合倒置光学显微镜的高速原子力显微镜原位实时观测光诱导纳米尺度偶氮聚合物运动

In-situ real-time observation of photo-induced nanoscale azo-polymer motions using high-speed atomic force microscopy combined with an inverted optical microscope

本文将针尖扫描式HS-AFM与倒置光学系统耦合，实现紧聚焦激光照射下偶氮聚合物纳米运动的原位实时成像与定量形貌分析。

All-optical switching in dye-doped DNA nanofibers

All-optical switches are introduced which are based on deoxyribonucleic acid (DNA) in the form of electrospun fibers, where DNA is semi-intercalated with a push-pull, luminescent nonlinear pyrazoline derivative. Optical birefringence is found in the organic nanofibers, with fully reversible switching controlled through continuous-wave laser irradiation. The photoinduced signal is remarkably large, with birefringence highlighted by optically-driven refractive index anisotropy approaching 0.001. Sub-millisecond characteristic switching times are found. Integrating dye-intercalated DNA complex sy…

Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

The mechanism of reversible photodegradation of 1-substituted aminoanthraquinones doped into poly(methyl methacrylate) and polystyrene is investigated. Time-dependent density functional theory is employed to predict the transition energies and corresponding oscillator strengths of the proposed reversibly- and irreversibly-damaged dye species. Ultraviolet-visible and Fourier transform infrared (FTIR) spectroscopy are used to characterize which species are present. FTIR spectroscopy indicates that both dye and polymer undergo reversible photodegradation when irradiated with a visible laser. Thes…