Light-tissue interactions of low level laser to support the chronic hepatitis patients

In this paper, we present some results obtained from the simulation of low power 633, 780, 850, and 940 nm laser in the liver by Monte Carlo method, with the model of the liver, consisting of 5mm derm, 7mm subcutaneous fat, 5 mm muscle layer. Based on these results, we fabricated devices called “Laser Semiconductor Optoacupuncture and phototherapy Device” using 780 and 940nm semiconductor lasers to treat chronic hepatitis. We combined with the doctor in An Giang province to clinical practice for 50 voluntary patients with chronic hepatitis. We used a 650 nm wavelength intravascular semiconductor laser treatment clinically to provide high-quality blood to the patients’ liver. Treating the phototherapy of the skin with two semiconductor laser beams with 780 nm and 940 nm wavelengths directly affects the liver from the surface of the abdomen. At the moment, we use the treatment on acupoint with 940nm- wavelength laser. A treatment course consists of 20 times for the patients is treated continuously. The patients tested with the ALT and AST before and after treatment with 3 courses. We use the SPSS 23 statistical method to evaluate the outcomes of treatment. The clinical symptoms of the patients such as fatigue, nausea, indigestion, fever, jaundice, yellow eyes almost completely have gone out after treatment. Low-level laser therapy offers a good response in patients with moderate to severe hepatic impairment such as the AST of 56.380 ± 10.162 and 39.260 ± 4.869; The ALT of 56.540 ± 13.580 and 41,360 ± 7,488 for before- and after treatments, respectively. Low-level laser therapy for patients initially has good results, high therapeutic effectiveness, no catastrophic or side Effects, and the statistical significance is p < 0.001.This research applied the ethical principles of the Helsinki Declaration in human researches. The research was carried out using non-invasive methods on humans with the regulations of the University of Technology, Vietnam National University Ho Chi Minh City, and the relevant regulations.

Nonlinear Dynamics of a Single-Mode Semiconductor Laser with Long Delayed Optical Feedback: A Modern Experimental Characterization Approach

Semiconductor lasers can exhibit complex dynamical behavior in the presence of external perturbations. Delayed optical feedback, re-injecting part of the emitted light back into the laser cavity, in particular, can destabilize the laser’s emission. We focus on the emission properties of a semiconductor laser subject to such optical feedback, where the delay of the light re-injection is large compared to the relaxation oscillations period. We present an overview of the main dynamical features that emerge in semiconductor lasers subject to delayed optical feedback, emphasizing how to experimentally characterize these features using intensity and high-resolution optical spectra measurements. The characterization of the system requires the experimentalist to be able to simultaneously measure multiple time scales that can be up to six orders of magnitude apart, from the picosecond to the microsecond range. We highlight some experimental observations that are particularly interesting from the fundamental point of view and, moreover, provide opportunities for future photonic applications.

Comparison of cutting and coagulation properties of 1.56 and 1.94 µm fiber lasers and a 0.98 µm semiconductor laser

Aim of the study was to compare the cutting and coagulation properties of 1.56 and 1.94 μm fiber lasers with those of a 0.98 μm semiconductor laser.Materials and methods. A comparative study of the biological effects of 1.56 and 1.94 µm lasers and a 0.98 µm semiconductor laser used in a constant, continuous mode was carried out. The cutting properties of the lasers were evaluated on the chicken muscle tissue samples by the width and depth of the ablation zone formed via a linear laser incision at a speed of 2 mm/s, while the coagulation properties were assessed by the width of the lateral coagulation zone. The zones were measured using a surgical microscope and a calibration slide. For statistical analysis, power values of 3, 5, 7, 9, and 11 W were chosen for each laser wavelength.Results. Analysis of the findings confirmed that laser wavelength had a statistically significant effect on the linear dependence between incision parameters and laser power. It was found that the 1.56 μm fiber laser (water absorption) had a greater coagulation ability but a comparable cutting ability compared with the 0.98 μm laser (hemoglobin absorption). When used in the power mode of 7W or higher, the 1.94 µm laser provided superior cutting performance compared with the 0.98 µm semiconductor laser at the same exposure power. Elevating the power in any of the lasers primarily increased the width of the ablation zone, and to a lesser extent – the crater depth and the width of the lateral coagulation zone. Therefore, in comparison with the 0.98 μm semiconductor laser, higher radiation power in the 1.56 and 1.94 μm lasers mainly influences their cutting properties, expanding the width and depth of the ablation zone, and has a smaller effect on their coagulation ability.Conclusion. The findings of the study showed that the 1.56 and 1.94 μm fiber lasers have better coagulation properties in comparison with the 0.98 μm semiconductor laser. was statistically proven that all incision characteristics (width of the lateral coagulation zone, depth and width of the ablation zone) for the 1.56, 1.94, and 0.98 μm lasers depend on the power of laser radiation. The 1.94 µm laser is superior to the 0.98 µm laser in its cutting properties.

SIGNAL PROCESSING AND CYBERSECURITY IN SOME CHAOTIC OPTICAL COMMUNICTAION SYSTEMS

A chaos –geometric approach to investigation of complex chaotic dynamical systems is applied to an analysis, modeling and processing the time series of emission intensities of chaotic transmitter/receiver systems (two unidirectionally coupled semiconductor laser systems in the all-optical scheme) suited for encoding at rates of GBit/s. the problem of a signal processing is directly connected with the corresponding cybersecurity in some optical chaos communictaion systems. The estimated values for the dynamic and topologic invariants such as the correlation and Kaplan-York dimensions, Lyapunov indicators, Kolmogorov entropy etc for investigated chaotic signal time series of two unidirectionally coupled semiconductor laser systems in the all-optical scheme.