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The development of laser industry and the increase in the intensity of laser radiation make the problem of protecting the vision organs and photosensitive sensors from high-intensity laser radiation more relevant. This paper presents the results for optical characteristics of phthalocyanine J-type dimeric complexes of Mg (phtMg) dissolved in dimethylformamide (DMF). Coherent Chameleon Ultra laser system was used as a source of laser radiation. The pulse duration was 140 fs, the pulse repetition rate was 80 MHz, and the wavelength was 810 nm. The studied solution didn’t exhibit nonlinear absorption properties (in contrast to the case of exposure by nanosecond radiation); the sample transmission remained unchanged with the increase in the intensity of the incident radiation. However, with the increase in the radiation power above 20 mW, an expansion of the beam was observed with the formation of a diffraction rings pattern due to spatial self-phase modulation induced by nonlinear refraction. The expansion of the laser beam allows the intensity of the laser radiation to be reduced by increasing the beam radius. Moreover, the addition of a diaphragm to the optical scheme, which "cuts off" a part of the incident radiation with an increase in the beam radius, makes it possible to reduce the radiation power getting in the sensor. This makes phthalocyanine complexes of Mg dissolved in DMF a promising material for use not only as a limiter of femtosecond pulsed radiation, but also as a nonlinear optical switcher for signal control in optical communication systems.

The effect of femtosecond laser (FSL) radiation on aqueous dispersions of a biocompatible nanomaterial containing bovine serum albumin (BSA) and single-walled carbon nanotubes (SWCNT) has been studied. Laser radiation was placed in a linear chain of carbon nanotubes and their aggregates. In this case, such a structure was observed at low concentrations of nanotubes ≤ 0.01 wt.% SWCNTs and an intensity of ~ 5 kW/mm2 of laser radiation per pulse. At high concentrations of ~ 0.1 wt. % SWCNTs, the ordering of SWCNTs under the influence of FSL radiation is weakly expressed due to the interlacing of numerous nanotubes. However, in this case, the specific electrical conductivity of the layers obtained after the drying of aqueous dispersions of BSA/SWCNTs under the action of FSL radiation increased several times. The prepared layers of biocompatible nanomaterial BSA/SWCNT will be in demand when creating sensors of various types, for example, deformation, gases or moisture.

Novel octabromo-substituted lanthanide(III) phthalocyanines were obtained via template method starting from corresponding 4,5-dibromophthalonitrile and identified by high-resolution mass-spectrometry, 1H nuclear magnetic resonanse and infra red spectroscopy. To achieve an initial 4,5-dibromophthalonitrile the reaction conditions of Pd(0) catalyzed cyanation were optimized. The peripheral bromine atoms impact on the optical properties of phthalocyanine complexes. The bathochromic shift of the main absorption band (Q band) was observed going from unsubstituted to octachloro- and then to octabromo-substituted phthalocyanines. All complexes demonstrated nonlinear optical responses in the DMF solution. Increasing the intensity of laser radiation leads to a nonlinear decrease in transmittance and further restoration of optical properties when switching back to linear mode. Nonlinear optical responses depend on the central ion nature. Europium phthalocyanine showed the enhanced nonlinear absorption coefficient compared to lutetium and terbium complexes. This was caused by an enhanced population of excited state and faster excitement for complexes with large central ions. The impact of peripheral bromine groups into nonlinear optical properties was determined through the comparison with unsubstituted analogues.