We present a theoretical study and simulation of an adaptive modal liquid crystal lens (AMLCL) where the magnitude and distribution of the surface resistance in the modal layer can be manipulated via radiation. The modal layer of the presented AMLCL is composed of various semiconductor materials that, consequently, define its surface resistance. To modulate the magnitude and distribution of its surface resistance via radiation, a photoconductive layer can be added to the modal layer. We model an AMLCL with 5-mm aperture and 20-μm thickness theoretically. The results show that the lens reaches its maximum optical power at a surface resistance of 160 MΩ / □ and a driving voltage of 6 V for a frequency fixed at 1 kHz, which is in close agreement with a previously reported experiment. The effect of irradiation with a Gaussian beam on the optical power of the AMLCL is analyzed for different beam waists. Results indicate that the optical power of the lens increases by 15% and remains constant until the beam waist of the pump light reaches 70% of the aperture diameter. At the same time, AMLCL aberration is reduced by 10%. The optical power decreases rapidly when the beam waist exceeds 70% of the aperture diameter.
Recently, compression optical clearing (OC) was applied to detect dermal carotenoid using reflection spectroscopy. To enhance the precision and accuracy of reflection spectroscopy to better detect the spectral absorption of beta-carotene inside biological phantom, here, we simultaneously use compression and immersion OC using dimethyl sulfoxide. In addition, we analytically extract the absorption coefficient of beta-carotene using diffuse reflectance spectroscopy (as an analytical OC). Our results show that the presented analytical OC can be applied alone as a noninvasive method to measure cutaneous chromophores at deep tissues. Finally, we also improve the ability of the analytical clearing method mediated with experimental OC. Our result demonstrates that the combination of analytical and experimental clearing methods enhance the ability of diffuse reflection spectroscopy for extracting the absorption coefficient of beta-carotene as one of the chromospheres inside biological phantom.
This study experimentally demonstrates the feasibility of utilizing zinc oxide nanorods for CO and CO2 gas detection via optical scattering. ZnO nanorods are grown on a plastic optical fiber to measure the effect of gas flow on the optical scattering at room temperature. The presence of nanorods minimizes the coupling of the Fresnel reflection. Placing the optical setup in a home-built gas chamber, an obvious distinguished change of the total reflection was observed when different gas concentrations were present. Reduction of reflection due to the presence of gas indicated that forward scattering leak has a dominant effect on the process. In addition, the results demonstrated that detection of CO gas at a concentration as low as 200 ppm had a higher response in comparison with CO2 gas.
This paper presents important parameters in performance of long-range surface plasmon (LRSP) structure (SF4/PVA/silver/PMMA-DR1) that are improved. We select poly(vinyl alcohol) (PVA) as the first dielectric layer due to its water solubility and good optical properties. The thickness of PVA and silver layers is optimized by transfer matrix method based on Fresnel equations. Surface morphologies of PVA and silver surfaces are analyzed by AFM imaging due to their important role in the performance of an LRSP structure. Furthermore, the sensitivity of an all-optical switch based on plasmon is investigated. In order to compare the sensitivity of LRSP and conventional surface plasmon (SP) structures in switching mode, full wide of half maximum, resonance angles, and pump powers of both structures are measured by a custom-made optical setup based on angular interrogation with a precision of 0.01 deg. Finally, we conclude that for creating equal signal levels in both samples, the required pump power for LRSP structure was about three times less than that for conventional SP; thus, these results led to power savings in optical switches.
This study demonstrates an analytical relation that models the carrier injection in metal-organic interfaces and which considers two consecutive carriers hopping as the injection mechanism. The new formula has superior attributes and can surpass conventional relations, in particular the thermionic emission-diffusion formula. For example, the model can properly trace the temperature dependency of the injection up to temperatures as low as 30 K and the full range of electric fields. Also, the prominence of joule heating for proper modeling of the injection is presented. This study examines the validity of the introduced analytical equation by exploring the injection in several practical contacts extracted from the literature, the results of which are discussed in this paper.
In order to improve the efficiency of optical polymers' function in photonic applications, the effect of local
environment on small molecules of Disperse Red 1 and their dynamic behavior is studied. Poly Styrene Sulfonic Acid
polymer used as host material to make highly doped polymeric thin films. By studying the samples' spectra in vitro and
in situ, and investigating the photo-anisotropic effects on samples, it is shown that dye-polymer interaction can be the
dominant factor in local environment around the dye molecules. Therefore, it can be used to increase significantly the
response intensity and improve the performance of photonic devices.
In this paper we present our studies of optical switching process in planar azo-dye Methyl Red doped polymeric
waveguides by using an Ar ion laser (488 nm) as pump beam and a He-Ne laser (633) as probe beam. The effects of
different parameters on optical switching process and effects of probe and pump beams on absorption spectrum of
sample were studied experimentally. The switching process is attributed to trans-cis photoisomerization of azodyes
followed by cis-trans thermal or optical relaxation that induces a reversible birefringence and dichroism in dye-doped
polymeric waveguides when pumped with polarized light.
In this article the effect of molecular weight of polyvinylcarbazol (PVK) on the photoluminescence (PL) spectra of
the solution of Coumarin 6 (C6) dye and the polymer in their common solvent and also thin film of PVK and the dye is
studied. By adding PVK to the C6 solution in dichloroethane, an extra peak was observed in the PL spectra of the
solution. The extra peak was more intense when high molecular weight PVK was used as compared with using the low
molecular weight polymer. Therefore in each polymer-dye solution, two peaks were detected in their photoluminescence
spectrum. The first peak is attributed to C6 emission and the second one may be related to the interaction of the C6
molecules with the solution of PVK in dichloroethane. This effect was only observed at low concentration of C6. At high
concentration of C6, excimer emission dominates PL spectra and results in a red shift for both peaks. At higher
concentrations, only one peak was observable and the excimer emission is stronger than that of lower concentrations. In
this case only one peak was observed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.