V. F. Lebedev

Spectral and generation properties of a new laser crystal (Cr3+,Li): Mg2SiO4

Based on the results of a comparative analysis of luminescence spectroscopy and EPR spectroscopy data, it was found for the first time that the wide-band luminescence of Cr3+ ions in a forsterite crystal is due to the Cr3+-VMg center or, in a crystal additionally doped with lithium, to a Cr3+-Li+ center. For the first time, tunable laser action was obtained with Cr3+-Li+ centers responsible for the wide-band luminescence.

Effect of high-energy electron irradiation on spectroscopic properties of forsterite single crystals

The influence of high-energy (2 1MeV) electrons irradiation on spectroscopic properties of both undoped and chromium doped forsterite (Mg2Si04) crystals, as well as the corresponding extent of radiation-resistance of the crystals has been studied for the first time. It was found that such kind of irradiation results in formation of the induced additional absorption (AA) in both undoped and chromium-doped crystals, independently of crystal growth atmosphere. This AA is broad, structureless band in the range 300-1 100 nm with flat maximum at -450nm. Simultaneously the strong AA in UV part of spectrum appears. The shape of the band with maximum at 450 nm is practically the same for e-irradiated and previously studied y-irradiated forsterite crystals. It is also insensitive to Cr3+/Cr4+ ratio in crystals, as well as to additional codoping of crystals by Li+-ions. On the contrary to the shape, the intensity of the AA substantially depends on all above mentioned factors. Meanwhile, the irradiation had not led to change of the ratio of concentrations Cr4+:Cr3+:C2+. Thus, like in other oxide crystals observed induced absorption in the visible spectral range is caused, apparently, by point defects formation in the host. Possibly, these defects are hole 0 centers (ionized oxygen). The AA in UV belongs, apparently, to metal-to-ligand (oxygen ion) change transition.

Cr3+,Li:Mg2SiO4 single crystal as promising active medium for one micron tunable solid state lasers

It has been established, for the first time, that the shift of luminescence of Cr3+ ions in forsterite from 900 to 950 nm (FWHM~240 nm) occurs gradually as the Li-codopant concentration is increased. Selectively excited polarized luminescence at 300 and 77 K is used to interpret the nature of the emitting Cr3+ centers. The features of the observed spectra can be explained by replacement of the initial Cr3+ centers by Cr3+-Li associates. The red shift of the Cr3+ luminescence peak and simultaneous reduction of the Cr2+ ions content are shown to be promising for the development of a tunable Cr3+-forsterite laser.

New view on optical quality of Cr 4+ :Mg 2 SiO 4 laser crystals: analysis of absorption spectra

Nowadays chromium-doped forsterite single crystals (Cr⁴⁺:Mg<inf>2</inf>SiO<inf>4</inf>) are one of the key elements of high power femtocecond lasers. Besides that on the base of two forsterite crystals Cr³⁺:Mg<inf>2</inf>SiO<inf>4</inf> and Cr⁴⁺:Mg<inf>2</inf>SiO<inf>4</inf> [1] and the same pump laser (on Al<inf>2</inf>O<inf>3</inf>:Ti³⁺ crystal) a CW laser device with the tuning of the generation wavelength in the wide range from 1095 to 1325 nm can be developed.

Influence of ionizing radiation on spectroscopic properties of chromium doped forsterite laser crystals

Chromium-doped forsterite single crystals (Cr:Mg/sub 2/SiO/sub 4/) are an active medium for solid-state lasers tunable near-IR region with use of Cr/sup 4+/ and Cr/sup 3+/ ions as active centers. The influence of high-energy electrons irradiation on absorption and luminescence spectra of Cr/sup 3+/- and Cr/sup 4+/-ions in forsterite laser crystals has been studied for the first time. The crystals were irradiated by 21 MeV electrons with fluence varied within the range 7/spl middot/10/sup 13//2/spl middot/10/sup 15/ cm/sup -2/. Gamma irradiation of the crystals with 1 MeV energy and a dose up to 3/spl middot/10/sup 5/ Gy had also been performed.

Pulsed and cw lasing in a new Cr{sup 3+}:Li:Mg{sub 2}SiO{sub 4} laser crystal

CW and pulsed lasing is obtained for the first time in Cr{sup 3+} ions in a forsterite (Mg{sub 2}SiO{sub 4}) crystal codoped with lithium ions. Pulsed lasing is tunable in the spectral range from 1030 to 1180 nm. (lasers)CW and pulsed lasing is obtained for the first time in Cr3+ ions in a forsterite (Mg2SiO4) crystal codoped with lithium ions. Pulsed lasing is tunable in the spectral range from 1030 to 1180 nm.

Temperature dependences of photoluminescence spectra of single-crystal Ca2GeO4:Cr4+ films

The temperature dependence of photoluminescence spectra in the wavelength range of 1.1–1.4 μm was measured at temperatures of 77–573 K in single-crystal Ca2GeO4:Cr+ films deposited onto the (110) surface of Ca2GeO4 single crystal and studied. The analysis of the spectra was based on the concept of interaction of emitting-center electrons with vibrations excited in the film. The results suggested that interaction of electrons with vibrations of the crystal lattice was suppressed and interaction with vibrations of the emitting center were dominant. The experimentally observed shift of the zero-phonon line in the spectra of the film in reference to that in the spectra of bulk single crystals is attributed to an increase in the symmetry of the oxygen tetrahedron in the olivine crystal structure; this increase is believed to be caused by the presence of defects in the films.

Particularities of the photoluminescence spectra of Cr4+:Ca2GeO4 single crystal films

It was found that the room-temperature photoluminescence (PL) spectra of Cr4+:Ca2GeO4 single crystal films grown by magnetron sputtering on Ca2GeO4 bulk single crystal substrates exhibit a sharp emission band in the region of ∼1.17 μm with satellites at ∼1.21 and 1.27 μm. Particularities of the PL spectra are interpreted within the framework of a model based on the interaction between electrons of the Cr4+ center and the oscillations excited in the film.

Luminescence of Ti{sup 3+} ions in silica glass

The d - d luminescence of Ti{sup 3+} ions was first observed in the double Ti/SiO{sub 2} system at room temperature. Silica glass doped with titanium was synthesised in a steady- state laser plume. The luminescent state was obtained by producing oxygen-deficient centres in the chemical reaction between Ti and SiO{sub 2}. Comparison of the luminescence and absorption spectra of the titanium-doped silica glass with the spectra of a Ti{sup 3+}:Al{sub 2}O{sub 3} crystal suggests that the 690-nm luminescence band belongs to Ti{sup 3+} ions. (laser applications and other topics in quantum electronics)