This work demonstrates the possibility of treating animals with malignant neoplasms using 608 nm of laser radiation by means of photodynamic therapy (PDT). The intracavity transformation of the Nd:YAP main radiation 1079 nm was Raman converted in barium nitrate crystal, and the Stokes frequency (1216 nm) was doubled using KTP or RTA crystals. The LiF or Cr:YAG crystals are used for the Q-switch. The radiation parameters were obtained at 100 Hz pump repetition frequency. The average power at 608-nm radiation with LiF and KTP was 700 mW at multimode generation. The 3-6 single 10-15 ns pulses were generated during one cycle of pumping. The doubling efficiency with RTA was two times more than with KTP. The cells of Ehrlich adenocarcinoma (0.1 ml) were implanted in hind thighs of ICR white non-imbred mice. Photosensitizer HpD was i.v. administered in a dose of 10 mg/kg. Ten animals were treated (2 as a control). There was a 9-30% decrease in the tumor growth depending on the irradiation dose. The better result (30%) was for the 200 J/cm2 dose radiation. These results show the possibility of using all solid state lasers with wavelength of 608 nm for PDT.
Processes of the optic pump energy transformation in system Raman converter-wideband laser medium with homogeneously broadening amplification band have been investigated. Raman converter and wideband medium were used in common cavity. As a Raman converter a barium nitrate and benzol were used, as a wideband media a LiF crystals with F-2 or F2 color centers and oxazyn-1 were used. Thanks to four-levels excitation scheme of the wideband media, pump output excitation threshold of them is less than for SRS excitation. In such system generation start from the widespread medium. The wideband medium amplify seeding radiation of the Raman converter at the Stokes frequencies, which get to the amplification band of the wideband medium. Then, thanks to additional Raman amplification, condensation of the wideband generation spectrum arise. Thus the threshold of the SRS excitation decreased and efficiency of the SRS increased in Stokes or anti-Stokes regions. Under certain conditions in liquid Raman media arise generation on the different types of the vibrations and generation on the combined frequencies too.
Considerable increase in efficiency of counterrunning and corunning SRS has been found in system SRS-element and broad-band electronic-vibrations amplifier medium. The characteristics of SRS-lasers with following SRS-elements: barium nitrate, benzol, nitrobenzol which were pumped by YAG-Nd and YAG-Nd lasers and characteristics of the laser with self- transforming active elements PGW-Nd. The broadband medium LiF with color centers inserted in scheme for amplification of the SRS. The efficiency of the pump transformation to the first Stokes was more than 50%. The results can be explained by resonance on first Stokes frequency occurs in coupling system-SRS-element-broadband amplifier medium.
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