Abstracts Track 2021

Area 1 - Lasers
Area 2 - Optics
Area 3 - Photonics

Area 1 - Lasers

Nr: 21
Title:

The Formation of Hybrid Resonant Cavities in the Semiconductor Circular Ring Laser Diode due to Optical Nonlinearity Effect
Authors:

Chun Ting Tsen, Wen How Lan and Ming Chang Shih
Abstract: We present the study of the emission characteristics of a semiconductor circular ring laser diode with a Y-junction output coupler that exists modes interaction between hybrid resonators formed by optical nonlinearity of the laser substrate. L-I and spectrum characteristics of both output terminals of these hybrid resonators were analyzed to explore the detailed of the mechanism of the formation of these hybrid resonators.
Nr: 29
Title:

Antimicrobial Activity of Amphiphilic Nanomicelles Loaded with Curcumin against Pseudomonas Aeruginosa Alone and Activated by Blue Laser Light
Authors:

Katia Rupel, Luisa Zupin, Silvia Brich, Giulia Ottaviani, Serena Zacchigna and Matteo Biasotto
Abstract: Antibiotic resistance poses an important challenge in modern medicine worldwide. A possible strategy to address this issue is the optimization of known antimicrobial compounds, such as curcumin CUR), by improving their bioavailability using nanotechnologies. The aim of this work was to assess the antimicrobial efficacy on Pseudomonas aeruginosa of nanomicelles loaded with CUR alone and activated by blue laser light in an antimicrobial photodynamic therapy (APDT) approach. The three amphiphilic molecules selected in this study displayed a common C16-long hydrocarbon chain and different amines as the hydrophilic portions: DAPMA (N,N-di-(3-aminopropyl)-N-methylamine), spermidine (SPD) and spermine (SPM). First, free CUR in liquid suspension and loaded in the three amphiphilic nanomicelles were tested with increasing concentrations both on bacteria and keratinocytes to determine both antimicrobial efficacy and safety towards eukaryotic cells. While free CUR exerted limited efficacy showing moderate cytotoxicity, a strong inhibition of bacterial growth was obtained using all three nanosystems without toxicity on eukaryotic cells. CUR-SPM emerged as the most effective, exerting antimicrobial activity up to a 250 nM concentration. Therefore, we selected CUR-SPM for further APDT experiments. We employed three sublethal blue laser (λ 445 nm) protocols (all with 0,1 W/cm2 irradiance, with increasing fluences of 6, 18 and 30 J/cm2) on previously ineffective concentrations of CUR-SPM. We found that the protocols characterized by a fluence of 18 and 30 J/cm2 further decreased the antimicrobial concentration to 50nM. To our knowledge, it is one of the lowest concentrations of CUR with antimicrobial effectiveness among those reported in literature so far. In the current work, among the CUR-loaded nanomicelles tested, the system based on CUR-loaded SPM nanomicelles showed the strongest antimicrobial effect against P. aeruginosa without cytotoxicity when tested on eukaryotic cells. Moreover, when the CUR-SPM nanomicelles were combined with laser irradiation, the photochemical effectiveness of the natural compound was greatly enhanced. These promising antibacterial results indicate that APDT can be considered as a potential approach to counteract P. aeruginosa infections, although further studies are necessary to unravel the APDT impact at molecular and cellular level.The combination of blue laser APDT with CUR-SPM nanomicelles results in an effective synergistic activity that represents a promising novel therapeutic approach on resistant species.

Area 2 - Optics

Nr: 9
Title:

Kerr Optoelectronic Effect Measurement of Pulsed Electric Fields (PEF) Generated in a Water-filled Capacitor by a 1 MV Generator
Authors:

Matthew Woodyard, Bucur Novac and Peter Senior
Abstract: Recently, a 1 MV class Tesla transformer based pulsed power generator has been designed and tested at Loughborough University. The generator has a water-filled capacitive load which will be used for proof-of-concept testing of novel non-invasive pulsed electric field food processing. To accurately measure the induced electric field, an optoelectronic system is installed, utilising the Kerr-effect in water. The paper will present a detailed description of the Kerr assembly and the results obtained, compared with predictions made using V-dot probes and a transient electromagnetic solver package.
Nr: 32
Title:

Static Laser Light Scattering Studies from DNA
Authors:

David Joseph
Abstract: Selmon sperm DNA had been used to study laser light scattering properties at different temperatures .and pH vales Our observation indicates that at a pH of 11.71, the molecules renature back to itself after getting denatured. Scattering studies have been done for different PH vales from alkaline to Acidic. These studies show that Static light scattering is a potent technique to probe DNA in different solvent environments.
Nr: 31
Title:

Development of Synthetic Routes and Their Influence on the Optical Properties of Eu3+-doped KY3F10 Materials
Authors:

Pablo Serna-Gallén, Héctor Beltrán-Mir and Eloísa Cordoncillo
Abstract: K(Y3-xEux)F10 phosphors with a dopant content between 0 and 5 mol% were prepared using different synthetic approaches. The reaction conditions have been critical factors for the morphology, size and crystallinity of the final products. As a result, interesting changes in their photoluminescence properties and lifetimes were observed. The study also revealed that quantum cutting processes or similar energy transfers between Eu3+ ions allowed obtaining high quantum efficiencies. In addition, the analysis of the Ω2 Judd-Ofelt parameter and the asymmetry ratio suggested that the crystal field of Eu3+ was very similar in all the prepared compositions. This work emphasizes the complex behavior of the fluoride-based systems, which are exceptional candidates for doping with luminescent lanthanide ions and have very important characteristics for their application in bioanalytics, biomedics or photonics. Indeed, the color-tunable emissions of the prepared materials, which vary from orangish to yellow depending on the synthesis and the Eu3+ percentage, could be interesting for their application in white light-emitting diodes through their combination with blue chips. This study has been recently published in the Journal Optics & Laser Technology (https://doi.org/10.1016/j.optlastec.2020.106734)

Area 3 - Photonics

Nr: 28
Title:

Structural Colour Switching of Oligomer Tethered 2D Nano Colloid under Electrophoresis and Dielectrophoresis Phenomena
Authors:

Asela Perera, Seung-Ho Hong and Jang-Kun Song
Abstract: Colour reflections of the recently discovered 2D nano colloids such as graphene oxide and α-zirconium phosphate (α-ZrP) is an attractive phenomenon which occurs due to Bragg optical diffraction. Reflective colour displays which can be developed using photonic crystals gain much attention due to providing a better solution for poor visibility issues that occur in conventional liquid crystal displays under bright circumstances. Redispersed nano colloid in organic solvent exhibits different colours with respect to concentration. These colours appear according to the wavelength of the reflected light due to change of interparticle and interlamellar distances. Tunability of nano colloidal dispersion under electric field is the most promising way to manipulate the structural colour reflections. Structural colour switching under electrophoresis which occurred due to charged particles in uniform electric field was investigated using α-ZrP nano colloidal dispersion. Electrophoresis experiments were carried out by applying low frequency (50 Hz) square waved alternating current (AC) signal with different direct current (DC) offset voltages. Time duration of the AC signal with offset voltages clearly affect to the uniformity of colour in the cell and the reaction time for the colour shift. If the duration is high uniformity of the colour was low and reaction time was high. Further, with appropriate electric field, the change of the structural colour reflections under electro hydrodynamic flow at low frequency (1 Hz) was observed. At that time structural colour changing was observed by destroying the lamellar assembly of the α-ZrP particles with dynamic flow. Dielectrophoresis; change of inter particle distance under non-uniform electric field was observed. Dielectrophoresis experiments were performed with low frequency (50 Hz) square waved AC signal with high voltage. Colour change was observed as a result of increase of the interparticle and interlamellar distances which occur due to particles moving out from the electric field. These qualitative results can provide a new approach to control photonic crystallinity of colloidal photonic crystals using electro hydrodynamics.
Nr: 30
Title:

Planar Cavityless Topological Laser
Authors:

Alexander Palatnik, Markas Sudzius, Stefan Meister and Karl Leo
Abstract: We report a one-dimensional (1D) planar topological laser, based on a topological interface state formed when two 1D photonic crystals with overlapping band gaps are brought into contact. We use a planar binary structure and achieve an interface state in the visible spectral region. The unit cell of each crystal is composed of two dielectric materials A and B with different refractive indices. In analogy to the Berry phase, a topological Zak phase can be ascribed to the photonic bands for such 1D crystals. The Zak phase can take two values: 0 for trivial and π for non-trivial topology, and depends on thicknesses ratio of these two materials dA⁄dB while the optical length of the unit cell remains constant. We incorporate a thin layer of an active organic material into the resonant structure, providing gain under an optical excitation. A transition from fluorescence to lasing under sufficiently strong pump energy density was observed. These results are the first realization of a planar topological cavityless laser, based on a topological interface state rather than on a cavity like most of other microlaser devices. We show that the topological nature of the interface state leads to a topological protection i.e. stability against layer thickness ratio variations: even for a large changes in thickness of layers next to the interface, the resonant state remains relatively stable, enabling design flexibility superior to conventional planar microcavity devices.