KEYWORDS: Optical proximity correction, Photomasks, Waveguides, Photonic devices, Lithography, Line edge roughness, Stochastic processes, Photonics, Signal to noise ratio
Photonics represents a growing opportunity to design and manufacture devices and integrated circuits for applications in high-speed data communications, advanced sensing, and imaging. Photonic technologies provide orders-of-magnitude speed improvements with reduced power consumption for data transmission and ultra-sensitive sensing capabilities in multiple application domains. Curvilinear patterns are required to maintain the physical properties of light propagation. We investigate the readiness of state-of-the-art mask synthesis tools to meet the challenges for photonics devices in terms of mask data preparation and verification. We apply OPC and ILT to photonic integrated circuit designs containing components sensitive to fabrication variation, to generate Manhattan and curvilinear mask data. Results are validated using a lithography verification tool considering smoothness of the printed curved structures, a key factor to maintain the correct functionality of the photonic devices. Rather than using ideal targets, we take simulation contours from corrected layouts for initial assessment of light propagation through wave guides. The impact of lithographic patterning related perturbations such as resist line edge roughness on optical performance is investigated based on results from a rigorous lithography process simulation model. Experimental data from fabricated devices underline the usefulness of lithography simulation to predict unwanted impact on device performance and the need of correction tools to counteract these effects.
Recently, we discovered, for the first time, reverse saturable scattering in a single gold nanoparticle. When incident intensity increases, the scattering intensity dependence of 80-nm gold nanoparticles evolves from linear, to saturation, and to reverse saturation sequentially. The intensity dependence in reverse saturable scattering region is significantly steeper than that in the linear region. With the aid of a confocal microscope, the full width half maximum of the single-particle point spread function can be reduced down to 80 nm, which is beyond the diffraction limit. Our finding shows great potential for superresolution imaging application without bleaching.
The wavelength and size dependencies of nonlinear scattering by a single gold nanosphere immersed in oil are presented. We show that the wavelength dependency fits well with the scattering spectrum by Mie solution, reflecting that the nonlinear scattering is dominated by the field enhancement from plasmonic effects. The tendency for different sizes is consistent with the results of degenerate four-wave mixing in the literature, showing that the saturation behavior is governed by the Kerr nonlinearity resonantly enhanced via intraband transition. Thus we conclude that the saturable scattering in our case is attributed to intraband χ(3), with nonlinear behavior enhanced by LSPR.
Conventionally, super-resolution imaging is achieved by manipulating the on/off switching of fluorophores, or by saturation of fluorescence emission. To prevent the photobleaching of fluorophores, we demonstrate novel superresolution imaging based on saturation of scattering from plasmonic particles, for the first time. With spectral studies, we have confirmed the saturation is directly linked to surface plasmon resonance effect. With the aid of saturation excitation microscopy, plus field concentration due to nonlinear plasmon resonance, we have achieved optical resolution below 80-nm based on scattering. Our study will open up a completely new paradigm for super-resolution microscopy.
In this work, we investigated, both theoretically and experimentally, the saturable scattering in a single gold
nanoparticle for the first time. In theoretical part, we used different models of the nonlinear properties to explain the
nonlinear responses in gold material. In experimental part, multi-color confocal microscopy was used to observe the
scattering of a single gold nanoparticle. As a result, by a resonant excitation, saturable scattering was observed with
moderate excitation intensity (~107 W/cm2); with even higher excitation intensity (>109 W/cm2), reverse saturable scattering was observed, indicating the existence of higher order nonlinear properties. To completely comprehend the
mechanism of this saturable scattering, we applied three kinds of excitation wavelengths (405nm, 532nm and 671nm) and
four kinds of gold nanoparticle with different diameters (40nm, 50nm, 80nm and 100nm) to demonstrate the wavelength
dependence and size dependence. Since the scattering of gold nanoparticles is significantly enhanced by localized surface
plasmon resonance, we compared these dependencies with the spectral properties induced by LSPR and found that they
match the spectra, revealing that the saturation is dominated by plasmon resonance. Besides, by fitting the dependencies,
linear and nonlinear hyperpolarizability of a single gold nanoparticle were also deduced.
With the aid of Maker fringe technique, we have observed two nonlinear optical (NLO) phenomena separately on diameter and
length of ZnO nanorod (NR). One is second harmonic generation (SHG) saturation in rod diameter, and the other is SHG
enhancement in rod length. Besides that, the model based on Lorentz local field is proposed for the first time to elucidate the above
phenomena. The deduced second order susceptibility χ(2) with various sizes of ZnO NR matches well to our theory, demonstrating
that the size effect on χ(2) is governed by Lorentz local field. Our theory provides a theoretical basis to explain the mechanism of
light-material interaction in nano-dimensions and is readily to be extended to other kind of semiconductor nanostructures when
addressing NLO properties in them.
In this study, we performed theoretical analysis and experimental measurement of third harmonic generation (THG) in
melanin solution with different concentrations. As predicted by theory, only THG at glass/solution interface was
observed due to Guoy phase shift effect. We have shown that this interfacial THG intensity is strongly affected by index
matching condition between the two media, leading to minimal THG at a certain melanin concentration. By fitting the
dependence of THG intensity versus melanin concentration, linear and nonlinear electric susceptibilities of melanin are
obtained, providing a valuable tool to characterize optical properties of biological molecules.
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.