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The role of the alkyl fragment of alkoxyamine initiating the homopolymerization of styrene is experimentally and theoretically studied in the case of 2,2,6,6-tetramethylpiperidine-1-oxyl derivatives. The rate constants of homolysis and recombination are measured for the alkoxyamines under study. The characteristics of polymerization initiated by these compounds are experimentally examined. The kinetics of polymerization is theoretically calculated with allowance for the measured kinetic parameters and the experimentally detected side reaction of hydrogen-atom transfer to the nitroxide radical during the thermolysis of alkoxyamine 2-cyano-2-isopropyl-TEMPO.

The objects mutual displacement measurement is an important task, particularly, the measuring of roll angles. New method for roll angles measuring of maneuvering objects based on anamorphosis effect is developed. Optical scheme for whole measurement system and for anamorphosis element is proposed. Equation for the static characteristic of the system and its graphical representation are showed.

The transfer of energy from Tm3+ to Ho3+ ions and also the interaction between excited Tm3+ ions and excited Tm3+ and Ho3+ ions in YSGG:Cr3+:Tm3+:Ho3+ and YSGG:Cr3+:Tm3+ crystals were studied quantitatively. The influence of these processes on the operation of two-micron lasers was analyzed.

An investigation was made of the luminescence spectra and lasing parameters of a YSGG:Cr3+:Tm3+ crystal. An active element 3 mm in diameter and 54 mm long was flashlamp-pumped (at T = 300 K) and its differential efficiency was 1% (λlas = 2.018 μm, 3H 4→3H 6 transition in Tm3+).

An analytic solution for the kinetics of nonlinear (upconversion) luminescence quenching in solid- state laser materials and other luminophosphors is obtained under the assumptions of hopping character of migration- assisted energy transfer and finite excitation life-time. It is shown how the observables of the luminescence experiment depend on microparameters of the energy transfer and ion concentrations. The critical ion concentrations separating different upconversion regimes are determined. The predictions of the theory are in agreement with experimental observations reported in the literature.

Processes of interaction of excited ions are investigated in several laser crystals: Er-Er -- in YSGG:Cr, Er and GSAG:Cr,Er crystals; Ho-Ho -- in YSGG:Cr, Ho crystals; Tm-Tm -- in YSGG:Cr,Tm and YAG:Cr,Tm crystals; Tm-Ho -- in YSGG:Cr, Tm, Ho and YSAG:Cr, Tm, Ho crystals; Cr-Cr -- in 11 of different laser crystals (ruby, YAG, GSGG, YSGG, LICAF, et al.); Cr-TR (Er, Ho, Tb, Tm, Nd, -- TR) in YAG, YSGG, GSGG, GSAG crystals.

The new low scandium content (20%) garnet YSAG:Cr3+,Ho3+,Tm3+ was grown with Czochralsky technique. It is of good optical quality, combines the advantages of YAG and YSGG crystals, demonstrates good spectroscopic and lasing properties and therefore is a promising active medium for 2 µm-lasers.

The paper presents the results of growth and spectroscopic study of chromium doped melilite - Ca2(MgxAlySi1−x−y)3O7. Melilite is isomorphic solid solution between akermanite - Ca2MgSi2O7 and gehlenite - Ca2Al2SiO7 [1]. The melilite crystals with varied composition from Ca2MgSi2O7 to Ca2Al2SiO7 were grown by floating zone method in air atmosphere. The growth rate was 4mm/h. The grown crystals were both doped with chromium and undoped. The crystal optical quality essentially improved, while the composition changed from Ca2MgSi2O7 to Ca2Al2SiO7.

The processes of excited Tm3+ and Ho3+ ions interaction in YSGG:Cr3+:Tm3+:Ho3+ and YSGG:Cr3+:Tm3+ laser crystals have been experimentally investigated. Their influence on 2-μm laser behavior has been analyzed.

The processes of excited Cr3+ interactions have been revealed and quantitatively investigated in a number of chromium-doped laser crystals.

The Czochralski method was used to synthesize a gadolinium scandium aluminum garnet (GSAG) single crystal activated with chromium (CCr = 2 × 1020 cm−3), thulium (CTm = 8 × 1020 cm−3), and holmium (CHo = 5 × 1019 cm−3) ions. The luminescence spectra and lasing properties were investigated. The experimental results indicated efficient energy transfer from the Cr3+ ions ( 2E and 4T2 states) to the Tm3+ ions ( 3F4 state), fast cross-relaxation sharing of the excitation of the Tm3+ ions (3F4 → 3H4, 3H6 → 3H4), and efficient energy transfer from the Tm3+ to the Ho3+ ions (3H4 → 3H6Tm3+, 5I8 → 5I7Ho3+). A GSAG:Cr3+:Tm3+:Ho3+ crystal in the form of a rod 4 mm in diameter and 36 mm long (with the length of the illuminated region 31 mm) was subjected to flashlamp pumping resulting in lasing at 2.09 μm. When the reflection coefficient of the exit mirror was R = 75% and the pump pulse energy was 100 J, the output radiation energy was 1.4 J, the differential efficiency amounted to 1.9%, and the threshold pump energy was less than 20 J. Such a laser may be useful in those cases when a high pulse repetition frequency is required.