A. B. Bykov

Room-temperature near-infrared tunable laser operation of Cr 4+ :Ca 2 GeO 4

Large crystals of highly doped Cr(4+):Ca(2)GeO(4) were grown by a top-seeded solution growth method. Absorption and emission measurements for various crystal orientations have been performed. From the spectroscopic measurements, the only optically active center was identified as tetrahedrally coordinated Cr(4+). Gainswitched, tunable laser operation of Cr(4+):Ca(2)GeO(4) crystal was demonstrated. Pulse energies of 0.4 mJ at 1.4 microm have been generated at a repetition rate of 100 Hz. Tunability over the 1348-1482-nm spectral range has been demonstrated.

Direct diode-pumped continuous-wave near-infrared tunable laser operation of Cr 4+ :forsterite and Cr 4+ :Ca 2 GeO 4

Continuous-wave tunable laser operation of direct diode-pumped Cr(4+):Mg(2)SiO(4) (Cr:forsterite) and Cr(4+):Ca(2)GeO(4) (cunyite) crystal were demonstrated. Diode-pumped Cr:forsterite was tunable over the 1236-1300-nm spectral range. The maximum output of 10 mW was measured at 1260 nm for 640 mW of pump power absorbed by the crystal. Diode-pumped laser operation of cunyite was also demonstrated over the 1390-1475-nm range. Free-running 20-mW output was centered at 1410 nm.

Spectroscopic study of transparent forsterite nanocrystalline glass–ceramics doped with chromium

We present a spectroscopic study of transparent forsterite nanocrystalline glass–ceramic doped with chromium, a promising active medium for near-infrared fiber-optic applications. Absorption, emission, excited-state absorption spectra, and continuous function decay analysis of luminescence decay reveal the presence of Cr3+ and Cr4+ centers in both glass and crystal phases. The optical behavior of Cr3+ and Cr4+ centers is discussed and compared with that in bulk forsterite crystals.

Femtosecond optical Kerr shutter using lead-bismuth-gallium oxide glass

Abstract A femtosecond Kerr shutter was demonstrated using a lead–bismuth–gallate oxide glass. The optical gating time was measured to be less than 350 fs and the peak Kerr transmittance was found to be 2.3 times larger than that of the standard Kerr CS 2 liquid medium, giving nonlinear Kerr coefficient n 2 =4.4×10 −11 esu.

Optical properties of neodymium activated crystalline nanostructures grown in transparent porous glass

Optical properties of neodymium self-activated nanocrystals grown in porous glass have been investigated. Mechanisms responsible for the opacity of pores glasses impregnated with solutions have been studied. Highly transparent glasses with nanocrystals grown in pores have been manufactured. Absorption, fluorescence, and fluorescence decay dynamic measurements were used to identify the phases grown in pores. We have shown that the major phase synthesized in the pores are crystal-like structures similar to that in bulk crystals. Optical properties of nanosize crystals differ from those in bulk single crystals because of specific size effects.

Direct diode-pumped laser operation of Cr 3+ - doped LiInGeO 4 crystals

Quasi-continuous wave (cw) laser action has been demonstrated by direct diode pumping of a new extremely broadband Cr(3+)-doped crystal. In contrast to previous works, where large-frame pump lasers have been employed, we have shown that low-power direct diode pumping of LiInGeO(4) is feasible, opening up the way for realizing compact and efficient laser sources for telecommunication applications.

Crystal growth and optical properties of Cr4+:Li2TiGeO5

Crystal growth and optical properties of Cr4+ centers in Li2TiGeO5 single crystals were investigated. Polarized absorption spectra at low and room temperature indicate a lowering of symmetry of the local environment of the Cr4+ ion from Td to C2 group of symmetry. The crystal field parameter Dq and the Racah paprameter B were determined to be Dq=930 cm−1, B=510 cm−1, and Dq/B=1.8. Emission spectra show wideband fluorescence from 1100 to 1600 nm with the maximum at 1200 nm. The lifetime of the metastable level decreases from 62 μs at 77 K to 6 μs at 300 K, indicating strong nonradiative quenching and a quantum efficiency of less than 10%.

Optical properties of Cunyite (Cr4+: Ca2GeO4) crystals co-doped with Er3 ions

Abstract The optical properties of Cr4+ centers in Ca2GeO4 (Cunyite) single crystals co-doped with Er3+ ions have been measured. Excitation of Cr4+ produces both Cr4+ fluorescence centered at 1280 nm and Er3+ fluorescence centered at 1550 nm. The cross-section of the 4 I 13/2 – 4 I 15/2 Er 3+ transition is estimated using Judd–Ofelt analysis to be 8×10 −21 cm 2 . The quantum efficiency of the energy transfer from Cr4+ to Er3+ is obtained based on measurements of the decay of fluorescence from Cr4+. The relative populations and gain coefficients of Cr4+ and Er3+ centers under pumping in the Cr4+ band are calculated with varying Er3+ concentrations. The co-doped Cunyite (Ca2GeO4) crystal can be used as an active optical medium for 1200 to 1600 nm region.

Ultra-wideband near-infrared laser operation of Cr/sup 3+/ centers in chromium doped Li(In,Sc)GeO/sub 4/ olivines

Tunable laser operation of octahedral Cr/sup 3+/ centers has been demonstrated in LiInGeO/sub 4/ and LiScGeO/sub 4/ single crystals. Tuning range from 1150-1480 nm for LiInGeO/sub 4/ and 1220-1380 nm for LiScGeO/sub 4/ has been achieved.

Fiber-laser-pumped Cr/sup 4+/:Ca/sub 2/GeO/sub 4/ laser

There is considerable interest in the development of all-solid-state, near-infrared tunable lasers for applications in the scientific and medical fields. Tunable laser operation of Cunyite (Cr/sup 4+/:Ca/sub 2/GeO/sub 4/) was first demonstrated with potential tunability in the 1.3-1.6-/spl mu/m range. Recently an all-solid-state cw Cunyite laser was reported that utilized a 1-W MOPA semiconductor diode device as the pump source. This paper describes the operation of an all-solid-state Cunyite laser pumped by a double-clad fiber laser.