High-efficiency polymethine dyes for passive Q-switch and mode locking of neodymium lasers

New polymethine dyes (PD) based on benzene [c, d] indole were synthesized. Their spectral and nonlinear optical characteristics in liquid and polymer media have been studied. It was found that the relaxation times τ of the excited state of the new PDs are approximately the same as those of the dye 3274y, which is widely used as a passive Q-switch of neodymium lasers with a generation lengthwave of 1.06 μm. The low sensitivity of τ to changes in the chemical structure of such PDs indicates that the main contribution to the deactivation of the excited state is made by the benzene [c, d] indole heterocycle. High values ​​of the cross section in the range of 1.05-1.08 μm at low relaxation times allow the studied PD to be easily bleached in lasers at low intensities (about 10 MW/cm2). It is established that the photostability of the new PD significantly exceeds that for the dye 3274y. This is because they contain a saturated six-membered ring in the polymethine chain, which is much less reactive than the corresponding five-membered ring of dye 3274u with respect to the photoinitiator of free radicals of UV irradiation. It is shown that the efficiency of Q-switching and mode locking of new passive laser shutters is higher than their analogues based on the dye 3274y.

Possibility of age-related changes correction in the face and neck skin using laser technology

The possibility of using combined erbium and neodymium lasers to correct the age-related changes in the face and neck skin by the «Fotona» apparatus using the «Fotona 4D» technique was investigated. To evaluate the results of the study in dynamics an index of age-related changes in skin was developed and applied. The results of photographic fixation and ultrasound of the facial and neck skin before and after laser procedures were also compared. It was determined, that the combination of two wavelengths of 2940 nm (erbium laser) and 1064 nm (neodymium laser) and the «Fotona 4D» technique with 4 patented technologies allows to carry out the procedure at the level of superficial, middle and deep structures of the face and neck tissues. Nowadays it is the only technology for non-invasive volumetric reconstruction and facial skin voluminisation, which is the result of a combination of synergistic methods of laser exposure. It was shown that one month after the second procedure of laser treatment, the face skin turgor increased, its dryness, pore severity, quantity and depth of wrinkles decreased, side effects and complications were absent. Ultrasound examination of the facial skin and index of age- related changes assessing in the face skin confirmed the positive dynamics of correction. Thus, the thickness of the skin in the area of nasolabial folds and superciliary arches increased by 0,5 mm (from 1,9 to 2,4 mm), derma by 0,6 mm (0,8 to 1 mm). The index of age-related changes assessing in the facial skin decreased by 10-13 points (before the procedure it was within the range of 20-24 points (average degree of age changes), after the procedure it was 11 points (mild degree of age changes). Thus, the use of combined erbium and neodymium lasers using the «Fotona 4D» technique showed a high efficiency of laser correction of age-related changes in the facial skin. Implemention of modern technologies in practice of dermatological clinics will improve skills of medical personnel on the use of laser technology.