Characterization of tracers for two-color laser-induced fluorescence thermometry of liquid-phase temperature in ethanol, 2-ethylhexanoic-acid/ethanol mixtures, 1-butanol, and o-xylene

Optical Limiting Properties of DNA Biopolymer Doped with Natural Dyes

The high-power lasers have important implications for present and future light-based technologies; therefore, the protection measures against their high-intensity radiation are extremely important. Currently, a great deal of interest is directed towards the development of new nonlinear optical materials for passive optical limiters, which are used to protect the human eye and sensitive optical and optoelectronic devices from laser-induced damage. Biopolymers doped with natural dyes are emerging as a new class of optical materials with interesting photosensitive properties. In this paper, the optical limiting capability of deoxyribonucleic acid bio-polymer functionalized with Turmeric natural dye has been demonstrated for the first time, to the best of our knowledge. The experimental investigation of the optical limit has been done by the Intensity-scan method in the NIR spectral domain at the important telecommunication wavelength of 1550 nm, using ultrashort laser pulses (~120 fs). Several optical properties of this natural dye are presented and discussed. The values of the optical transmittance in the linear regime, the saturation intensity of the nonlinear transmittance curves, and the coefficient of the nonlinear absorption have been determined. The influence of the DNA biopolymer and natural dye concentration on the optical limiting properties of the investigated biomaterials is reported and discussed. The photostability and thermal stability of the investigated solutions have also been evaluated by monitoring the temporal decay of the normalized absorption spectra under illumination with UVA light and heating, respectively. Our results evidence the positive influence of the DNA, which embeds Turmeric natural dye, on the optical limiting functionality itself and on the photostability and thermal stability of this novel material. The performed study reveals the potential of the investigated novel biomaterial for applications in nonlinear photonics, in particular in optical limiting.

Influence of continuous wave laser light at 532 nm on transmittance and on photoluminescence of DNA-CTMA-RhB solutions

Recent results obtained in our experimental investigation on the influence of the illumination with continuous wave (c.w.) laser light at 532 nm on the transmittance at this wavelength and on the photoluminescence of the DNA-CTMA-RhB in butanol compound are reported. The temporal dependence of absorption changes induced by c. w. light at 532 nm in DNA-CTMA-RhB in butanol solution, and, for comparison, in RhB in butanol solution, is investigated experimentally and analyzed in order to assess the effect of DNA-CTMA on this light-induced process. The evolution in time of the peak's amplitude and wavelength of the photoluminescence spectra in solutions of DNA-CTMA-RhB in butanol, during their excitation with laser light at 532 nm wavelength has been also investigated and discussed.

DNA-CTMA Matrix Influence on Rhodamine 610 Light Emission in Thin Films

Due to the increased application of lasers in different fields (industry, medicine, etc.), there is a growing need for new laser sources with good beam quality and variable emission wavelength. At the same time, for environmental reasons, the obtaining of novel eco-friendly active optical materials, such as those based on the deoxyribonucleic acid (DNA) biopolymer, with optimal light emission properties, is of high interest. The results obtained in this study of the temporal dependence of the transmittance and of the light emission in thin films of DNA-CTMA-Rhodamine 610 (at different Rhodamine concentrations) (DNA-CTMA-Rh610), when they are illuminated with continuous wave laser light at 532 nm (frequently used in the optical pumping of dye lasers), are presented and discussed. The transmittance results obtained for thin film samples are compared to those obtained for the DNA-CTMA-Rh610 solutions in butanol, from which the films have been made, and also with those obtained for Rh610 solutions in butanol with the same concentrations. The investigation was performed in order to assess the influence of the DNA-CTMA and of the green laser light at 532 nm wavelength on relevant chromophore properties such as light transmission and fluorescence emission. The results obtained revealed that the DNA-CTMA matrix has an active influence on the Rhodamine 610 emission, in the whole range of concentrations of the investigated samples.

Development of a Temperature Distribution Measurement System for Transmission Oil for Transportation Equipment

In this study, an optical sensor using thermo-sensitive phosphor and its measurement system for visualizing and measuring the temperature distribution in an arbitrary cross-section of transmission oil using one type of phosphor, whose peak wavelength changes with temperature, is proposed. Because the intensity of the excitation light is gradually attenuated by the scattering of the laser light owing to microscopic impurities in the oil, we attempted to reduce the scattering effect by increasing the excitation light wavelength. Therefore, Pyrromethene 597 was selected as the optical sensor using thermo-sensitive phosphor, and a DPSS (Diode Pumped Solid State) laser with a wavelength of 532 nm was used as the excitation light. Using this measurement system, we measured the temperature distribution of a vertical buoyant jet of transmission oil and validated the measurement method. In addition, it was shown that this measurement system could be applied to the measurement of the temperature distribution in transmission oil with cavitation foaming.

Laser applications to chemical, security, and environmental analysis: introduction to the feature issue

This Applied Optics feature issue on laser applications to chemical, security, and environmental analysis (LACSEA) highlights papers presented at the LACSEA 2020 Seventeenth Topical Meeting sponsored by The Optical Society (OSA).