In the last couple of decades huge effort has been put into development of photonics platforms based on various materials such as Si, Si3N4, InP, LiNbO3, GaAs and others. Only few of them (Si, Si3N4, InP) have turned into eco-systems resembling semiconductors industry of design house, foundries, fabless companies and multi project wafer (MPW) services of photonics integrated circuits (PICs). While various photonic platforms have matured to industrial level, they still have numerous challenges including limits set by material properties, expensive fabrication and complicated hybrid integration.
Polymer materials provide numerous advantages over semiconductor and oxide/nitride platforms: combination of passive and active elements, simple fabrication techniques, Integration of other elements for hybrid platform, wide wavelength range and multilayer structure.
We will present the results of developed polymer photonic platform with active and passive elements based on SU-8 and polymethylmethacrylate photoresist.
We demonstrate an integrated on-chip whispering gallery mode (WGM) ring resonator tested for humidity sensing. When developed, SU-8 is chemically and mechanically stable, as well as optically transparent above 400 nm wavelength and it has a high refractive index. Therefore, it is a suitable material for optical WGM resonators. When light is coupled in the resonator, it circulates along the surface for prolonged periods of time interacting with the surrounding environment. Resonance wavelength depends on the refractive index and/or the radius of the resonator. Polymers, including SU-8, are sensitive to gas and temperature changes in the environment. We tested the ring resonators in changing relative humidity (RH). Due to changes in RH, the refractive index of SU-8 changes, and we observed a shift in the resonance wavelength. While the sensitivity was average compared to similar studies using other materials or geometries, the ring geometry showed excellent response and recovery times. This property is important in many areas, such as industrial production and environmental monitoring.
In this paper, we present a study on nonlinear optical effects in two types of core-shell nanoparticles with different claddings - thiol-termination ligand and sodium citrate/PVP claddings. Nanoparticles were dissolved in Dichloromethane and studied using the Z-scan method. As laser sources we used a tunable laser with 150 fs pulse width and 500 kHz pulse repetition rate. To study what processes lead to refractive index changes we used the polarization-resolved Z-scan method. A strong thermal response was observed for spherical nanoparticles. Both nanoparticles had similar spectral dispersion for Two-photon absorption, but spherical had a much stronger Kerr response.
In recent years, lossy mode resonance (LMR) biosensors have proven to be promising devices for the analysis of biological entities. In this work, for the first time, the possibility of observing the LMR effect in photonic integrated sensor based on SU-8 waveguides for biosensing applications is presented. SU-8 is a polymer that is ideally suited for optical waveguide applications due to its very high optical transparency, chemical stability and simple fabrication process. The LMR effect is achieved by using ZnO and TiOx claddings over the waveguides. The influence of different cladding thicknesses and materials on the LMR effect is demonstrated. Different design waveguides are tested. Potential future applications and development steps of integrated LMR sensor will be discussed.
In this paper, we present a study on thermo-optical effect in core-shell silver/thiol-termination ligand nanoparticles. Nanoparticles were dissolved in Dichloromethane. Experimental measurements were carried out using a Z-scan setup. As laser sources we used two 1064 nm lasers: i) 28 ps pulse width laser with 1000 Hz pulse repetition rate; ii) 8 ns pulse width laser with changeable pulse repetition rate 200 – 40 000 Hz. To study what processes lead to refractive index changes we used the polarization-resolved Z-scan method. Comparing ps and ns results showed that response time of single pulse thermal effects for organic solvents depends on beam size while for nanoparticles it corresponds to nanoparticle size. Measurements with ns laser using different lenses and pulse repetition rate showed that thermal response scales with the ratio of laser pulse repetition rate times beam size squared.
We demonstrated a new approach to measuring third-order nonlinear optical effects using an experimental setup incorporating both Z-scan and Mach-Zehnder interferometer methods. This method could be especially purposive for thermo-optical effect studies as it can simultaneously probe thermal gradient profile as well as absolute temperature changes induced by an optical beam. The experimental setup was tested using chloroform. Experimental measurements were carried out using 1064 nm Nd:YAG laser with 8 ns pulse width and 40 kHz pulse repetition rate. The measured nonlinear refractive index of chloroform was mainly induced by the thermo-optical effect. As thermo-optical response depends on beam size at focal length, measurements were carried out with 35 mm and 125 mm focal length lenses. Measured nonlinear refractive index values of Z-scan and interferometric measurements gave the same value indicating that this method can be used for thermo-optical effect studies.
In this paper we report the results of studied nonlinear optical properties of DMABI-Ph6 in form of solutions with chloroform as solvent and guest-host thin films with poly(methyl methacrylate) as host material. We implemented the Zscan method for studies of Kerr and two-photon absorption of selected material. During experimental measurements we used 1064 nm Nd:YAG laser with 30 ps pulse duration and 10 Hz repetition rate. From acquired values of Kerr coefficients we calculated values for real part of third-order susceptibility, as well as second-order hyperpolarizability. Acquired data for DMABI-Ph6 were compared with data for other ABI derivatives studied previously to describe how different donor and acceptor groups influence third-order nonlinear optical properties.
We describe the sample preparation and experimental setup for second harmonic generation measurement of electro-optical (EO) chromophore/polymer system at the time of contact-poling. Different types of spacers for avoiding electric breakdown due to avalanche multiplication are compared. Electric field threshold values for second harmonic generation are observed in all samples.
We studied nonlinear optical properties of two different aminobenziliden-1,3-indandione derivatives – DDMABI and DMABI-OH by employing the Z-scan method. Through this we described how different donor and acceptor groups influence third-order nonlinear optical properties such as Kerr effect and two-photon absorption. During experimental measurements we used 1064 nm Nd:YAG laser with 30 ps pulse duration and 10 Hz repetition rate. From acquired values of Kerr and two-photon absorption coefficients we calculated values for real and imaginary parts of third-order susceptibility, as well as second-order hyperpolarizability. Quantum chemical calculations were carried out for secondorder hyperpolarizability to study how well calculations correlate with experimental values. Acquired data for DDMABI and DMABI-OH were compared with data for other ABI derivatives studied previously.
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