New light-driven actuators based on films of polymer polyvinylidene fluoride are described. The actuators use the
photomechanical bending of the polymer film caused by low power laser radiation. The photomechanical effect
combines physical mechanisms, such as anisotropic thermal expansion, converse piezoelectric mechanism, photovoltaic
and pyroelectric, while thermal expansion is dominant for slow motion. Mechanical vibrations of the strips of the
photomechanical polymer were observed with periodic pulsed laser excitation. The resonance frequency is inversely
proportional to the square of the length of the strip, in agreement with the theory. Resonance frequency measurements
were used to determine the modulus of elasticity of the films, which was close to 3.0x109 Pa. Three possible applications
are a photonic switch, an adaptive mirror, and an auto-oscillator. The proposed actuators have a potential of being used
as the components of future light-driven micro/nano systems.
New light-driven actuators based on films of polymer polyvinylidene fluoride are described. The actuators
employ the photomechanical bending of the polymer film caused by low power (10 mW and less) laser radiation.
The photomechanical effect combines various physical mechanisms, such as anisotropic thermal expansion,
converse piezoelectric mechanism along with photovoltaic and pyroelectric ones, while the mechanism of
thermal expansion is dominant for slow motion. Mechanical vibrations of the strips of the photomechanical
polymer were observed with periodic pulsed laser excitation. The resonance frequency is inversely proportional
to the square of the length of the strip, in full agreement with the theory. Resonance frequency measurements
were used to determine the modulus of elasticity of the films, which was close to 3.0×109 Pa. Two possible
applications were discussed: optical fiber switch and adaptive mirror propelled by the proposed actuators. The
actuators have a potential of being used as the components of future light-driven micro/nano systems.
We describe new light-driven actuators based on films of polymer polyvinylidene fluoride, known as PVDF. The actuators employ the photomechanic bending of the polymer film caused by low-power (10 mW and less) laser radiation. The photomechanic effect combines various physical mechanisms, such as thermal expansion, the converse piezoelectric mechanism, and the photovoltaic and pyroelectric mechanisms, while the mechanism of thermal expansion is dominant. The force applied by the actuators to external objects is measured with a torsion balance. It is proportional to the power of laser beam and could be as high as 10–4 N for a 50-µm film illuminated with a 10-mW laser beam. We demonstrate mechanical vibrations of a 1×7-mm strip actuator at a frequency of 0.3 kHz. As examples of possible applications, a photonic switch and an actuator with a closed-loop motion that could drive the inner workings of a conventional mechanical clock were demonstrated. The proposed actuators have a potential of being used as propulsion components of future light-driven micro/nano systems.
New light-driven actuators based on films of polymer polyvinylidene fluoride are described. The actuators employ the photomechanical bending of the polymer film caused by low power (10 mW and less) laser radiation. The photomechanical effect combines various physical mechanisms, such as anisotropic thermal expansion, converse piezoelectric mechanism along with photovoltaic and pyrolelectric ones, while the mechanism of thermal expansion is dominant for slow motion. The static force applied by the actuators to external objects was measured with a torsion balance. It is proportional to the power of laser beam and could be as high as 10-4 N for a 50- micron film illuminated with a 10-mW laser beam. Mechanical vibrations of the strips of the photomechanical polymer were observed when the periodic laser pulses were used. The resonance frequency is inversely proportional to the square of the length of the strip. Resonance frequency measurements were used to determine the modulus of elasticity of the films, which was close to 3.0x109 Pa. Two possible applications are discussed: photonic switch and adaptive mirror. The proposed actuators have a potential of being used as the components of future light-driven micro/nano systems.
Ferroelectric Lithium Niobate (LN) possesses a combination of unique electrooptic, piezoelectric, pyroelectric, and photorefractive properties. These features make it suitable for applications in optical devices-as modulators, switches, and filters in communication systems and holographic recording medium, etc. Here, the growth of lithium Niobate doped with iron and doubly doped with iron and manganese ions will be described. The growth technique will be through Automatic Diameter Control Czochralski Design. From these grown crystals, critical electrooptical coefficients using null detection polarimetry are provided. The results of growth, electrooptic measurements, and some physical properties are compared and presented. Also, the use of doped LN crystals in devices is discussed.
The intensity dependent index of refraction and themolecular two-photon absorptivity (TPA) of 3,3'-dielthylthia-cyanine iodide (DETCI) has been measued in a range of solvents by the femtosecond z-scan technique. In DMSO, where DETCI is quite soluble, both the two-photon absorptivity and the nonlinear index of refraction are linear functions of concentration. In contrast, the two photon absorptivity and non-olniear index change of DETCI in MeOH is an order of magnitude lower and shows signs of saturation at concentrations well below the saturation limit. In high index solvents such as MeOH, the TPA of DETCI is much smaller in lower index solvents such as DMSO. The intensity dependent index chagne, n2 is large and relatively insensitive to the index of the solvent.
The intensity dependent index of refraction and the molecular two-photon absorptivity (TPA) of 3,3'-dielthylthia-cyanine iodide (DETCI) has been measured in a range of solvents by the femtosecond z-scan technique. In DMSO, where DETCI is quite soluble, both the two-photon absorptivity and the nonlinear index of refraction are linear functions of concentration. In contrast, the two photon absorptivity and non-linear index change of DETCI in MeOH is an order of magnitude lower and shows signs of saturation at concentrations well below the saturation limit. In high index solvents such as MeOH, the TPA of DETCI is much smaller in lower index solvents such as DMSO. The intensity dependent index change, n2 is large and relatively insensitive to the index of the solvent.
The nonlinear optical absorption of a range of dialkyl- carbothiacyanine dyes has been measured using intensity dependent transmission measurements of the absorption cross- section at 532 nm. The ground and effective excited state absorption cross-section for each of the dyes has been determined. It was observed that with increasing bridge conjugation length between the carbothiacyanine end groups, the absorption cross section of ground state decreases slightly while the absorption cross-section of the excited state increases leading to an overall increase in the absorption cross-section ratio by an order of magnitude from 0.3 to 5.29. The absorption cross-section ratio tracks linearly with the difference between the energy of the pump laser and the energy of the ground state absorption. The counter ions of the dyes also affect the nonlinear absorption significantly. These organic materials exhibit good potential for optical limiting applications.
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