V. Petricevic

Generation of sub-100-fs pulses from a CW mode-locked chromium-doped forsterite laser

Generation of femtosecond pulses from a continuous-wave mode-locked chromium-doped forsterite (Cr (4+):Mg(2)SiO(4)) laser is reported. The forsterite laser was actively mode locked by using an acousto-optic modulator operating at 78 MHz with two Brewster high-dispersion glass prisms for intracavity chirp compensation. Transform-limited sub-100-fs pulses were routinely generated in the TEM(00) mode with 85 mW of continuous power (with 1% output coupler), tunable over 1230-1280 nm. The shortest pulses had a 60-fs pulse width.

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.

Near infrared tunable operation of chromium doped forsterite laser

Tunable, room temperature pulsed laser operation of a chromium-doped forsterite laser for 1064-nm pumping is reported. Using different sets of mirrors and a single birefringent plate as the intracavity wavelength selecting element, tunability over the 1167-1345-nm spectral range has been demonstrated.

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.

Continuous-wave mode-locked operation of a chromium-doped forsterite laser

Mode-locked operation of chromium-doped forsterite (Cr:Mg(2)SiO(4)) has been achieved for the first time to our knowledge. The chromium-doped forsterite laser has been mode locked by using two methods: active mode locking, which produced pulses as short as 31 ps tunable between 1204 and 1277 nm, and synchronously pumped mode locking, which produced pulses of 260-ps duration tunable between 1195 and 1295 nm.

Laser action in chromium-activated forsterite for near-infrared excitation

Recently, the authors reported room-temperature pulsed-laser action in chromium-activated forsterite (Cr:Mg/sub 2/SiO/sub 4/). The free-running laser output was centered at 1235 nm with a spectral bandwidth (full width at half-maximum,FWHM) of 22 nm. The laser emission was stimulated by the 532-nm excitation of the green-red absorption band of the system. The crystal is characterized by a shallow absorption band spanning the 850-1200-nm wavelength range, which overlaps a significant portion of the emission spectrum and was previously thought to inhibit laser action in that region. In this communication, laser action in chromium-doped forsterite for 1064-nm excitation of this band is reported. The near infrared absorption thus turns out to be effective in populating the initial level of the lasing transition.

Synthesis and spectroscopic properties of (Cr4+) doped sol-gels

The low temperature sol-gel process has been used for the preparation of Cr 4 -doped multicomponent gels and olivine group ceramic powders. Although absorption spectra indicate the presence of tetrahedrally coordinated Cr 4+ in the silicate-aluminate and germanate glasses, none exhibit near-IR emissions at room temperature. Cr(III) doping of Mg 2 SiO 4 , Ca 2 GeO 4 and the aluminates MAlO 2 (M = Li, Na and K) yield transparent materials with absorption spectra indicative of octahedrally coordinated Cr(III). Heating these transparent materials produces powders that exhibit absorption and near-IR emissions spectra characteristic of tetrahedrally coordinated Cr(IV).

Kilohertz Cr:forsterite regenerative amplifier

Summary form only given. Cr:forsterite is a vibronic laser source tunable in the near-infrared spectral region in the range 1.15-1.35 /spl mu/m. In this paper, we report for the first time, to our knowledge, on the operation of a regenerative amplifier system based upon Cr:forsterite. Self-mode-locked Cr:forsterite lasers have generated pulses as short as 25 fs, theoretically the large bandwidth of the Cr:forsterite laser emission can support sub-20-fs pulses. To minimize optical damage in the amplifier rod we have utilized the technique of chirped pulse amplification (CPA).

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.