M. Tonelli

Efficient visible laser emission of GaN laser diode pumped Pr-doped fluoride scheelite crystals

In the present work we report on the growth, spectroscopy and laser results of diode pumped Pr-doped LiYF(4), LiLuF(4) and LiGdF(4) fluoride, scheelite-type structure crystals. We measured the polarisation dependent absorption and emission properties as well as the decay time of the (3)P(0) level. Exploiting the (3)P(2) absorption around 444 nm, we obtained efficient laser emission under GaN laser diode pumping on several transitions from the green to the near infrared wavelength range.

Quantum Physics Exploring Gravity in the Outer Solar System: The SAGAS Project

We summarise the scientific and technological aspects of the Search for Anomalous Gravitation using Atomic Sensors (SAGAS) project, submitted to ESA in June 2007 in response to the Cosmic Vision 2015–2025 call for proposals. The proposed mission aims at flying highly sensitive atomic sensors (optical clock, cold atom accelerometer, optical link) on a Solar System escape trajectory in the 2020 to 2030 time-frame. SAGAS has numerous science objectives in fundamental physics and Solar System science, for example numerous tests of general relativity and the exploration of the Kuiper belt. The combination of highly sensitive atomic sensors and of the laser link well adapted for large distances will allow measurements with unprecedented accuracy and on scales never reached before. We present the proposed mission in some detail, with particular emphasis on the science goals and associated measurements and technologies.

Visible laser emission of solid state pumped LiLuF(4):Pr(3+).

In this work we investigate visible transitions of Pr in the crystal Pr:LiLuF4. In particular we will report on the growth, emission and absorption spectroscopy as well as laser action at four different wavelengths. Findlay-Clay and Caird analysis have been carried out in order to characterise the cavity and the crystal quality. To the best of our knowledge the reported slope efficiencies are the highest reached for a Pr-based laser.

Efficient broadly tunable continuous-wave Cr 2+ :ZnSe laser

An efficient continuous-wave Cr2+-doped ZnSe laser pumped by a Co:MgF2 laser is experimentally demonstrated. In a single-pass pump scheme we observed up to 520 mW at ∼2500 nm in 0.4-nm narrow-band operation, with 52% incident-power slope efficiency, and a tuning range between 2180 and 2800 nm. In the multipass pump scheme we also observed and analyzed the effect of dual Q-switching laser action at 1.75 and 2.5 µm in the Co:MgF2–Cr:ZnSe coupled-cavity oscillator. Finally, we report the measurement of the passive losses and of the ground-state absorption at the lasing wavelength.

Optical spectroscopy of Ca3Sc2Ge3O12 : Ni2+

Abstract The optical spectra of Ca3Sc2Ge3O12 (CaSGG) single crystals doped with Ni2+ are presented. Analysis of the absorption spectrum shows that the dopant substitutes mainly for Sc3+ in octahedral sites and, to a lesser extent, Ge4+ in tetrahedral sites. The optical transitions were assigned in the framework of the Ligand Field theory and the Dq, B and C parameters were obtained for both coordination geometries. Three emission transitions were observed in the green, red and infrared regions and were assigned to the 1T2(1D) → 3A2(3F), 1T2(1D) → 3T2(3F) and 3T2(3F) → 3A2(3F) transitions of Ni2+ in octahedral sites, respectively. No luminescence from Ni2+ in tetrahedral sites was observed.

Compact passively Q-switched diode-pumped Tm:LiLuF4 laser with 1.26 mJ output energy.

We demonstrate efficient continuous-wave (CW) and passively Q-switched Tm:LiLuF(4) laser operation near 1.9 μm. The CW slope efficiency reached 54.8% with respect to absorbed power. Stable passive Q-switching with Cr(2+):ZnS saturable absorbers resulted in minimum pulse duration of 7.6 ns and maximum pulse energy and peak power of 1.26 mJ and 166 kW, respectively.

Optical refrigeration to 119 K, below National Institute of Standards and Technology cryogenic temperature

We report on bulk optical refrigeration of Yb:YLF crystal to a temperature of ~124 K, starting from the ambient. This is achieved by pumping the E4-E5 Stark multiplet transition at ~1020 nm. A lower temperature of 119±1 K (~-154C) with available cooling power of 18 mW is attained when the temperature of the surrounding crystal is reduced to 210 K. This result is within only a few degrees of the minimum achievable temperature of our crystal and signifies the bulk solid-state laser cooling below the National Institute of Standards and Technology (NIST)-defined cryogenic temperature of 123 K.

Continuous-wave ultraviolet generation at 320 nm by intracavity frequency doubling of red-emitting Praseodymium lasers

We describe a new approach for the generation of coherent ultraviolet radiation. Continuous-wave ultraviolet light at 320 nm has been obtained by intracavity frequency doubling of red-emitting Praseodymium lasers. Lasing at the 640-nm fundamental wavelength in Pr:LiYF(4) and Pr:BaY(2)F(8) was realized by employing an optically pumped semiconductor laser at 480 nm as pump source.Using LiB(3)O(5) as nonlinear medium, ~19 mW of ultraviolet radiation with ~9% optical efficiency with respect to absorbed power was reached for both laser crystals; the visible-to-ultraviolet conversion efficiency was 26% and 35% for Pr:LiYF(4) and Pr:BaY(2)F(8), respectively.

Diode-pumped passively mode-locked Yb:YLF laser

We demonstrate passive mode-locking by means of a semiconductor saturable-absorber mirror in a diode-pumped Yb:YLF laser. We present crystal growth process, spectroscopic measurements, and investigation of mode-locking performance. Pulse trains with minimum duration of 196 fs, average power of 54 mW and a repetition rate of 55 MHz were obtained. The optical spectrum, centered at 1028 nm, has a 7.1-nm bandwidth leading to nearly transform-limited pulses.

Orange and red upconversion laser pumped by an avalanche mechanism in Pr3+, Yb3+:BaY2F8

The letter reports on upconverted orange (607.5 nm, 3P0→3H6) and red (638.7 nm, 3P0→3F2) laser oscillation at room temperature observed in Pr3+, Yb3+:BaY2F8 under excitation at 822 or 841 nm at 300 K. The upconversion mechanism that populates the emitting level is an avalanche excitation mechanism. Output powers up to 55 mW and slope efficiencies up to 27% were demonstrated at 607.5 nm. At 638.7 nm, the maximum output power was 26 mW with a slope efficiency of about 13.5%.