1. Proposer and coordinator Ist. di Fisica Applicata Carrara IFAC-CNR, Firenze Project Coordinator : Dr. Matteo Vannini Design and development of Ce:LiCAF and Ce:LiLuF laser prototypes Partners Physics Dept., Pisa University - Prof. Mauro Tonelli Growth of Ce:LiLuF and other experimental crystals with Ce doping ENEA, Optical Components group - Dr. Angela Piegari Casaccia Research Center, Roma Development of optical components with multilayer coatings for UV lasers Funding Fondo Speciale per lo Sviluppo della Ricerca di Interesse Strategico (Art. 51, comma 9, legge 27.12.1997 n.449) - Anno 2000 Ce-doped laser media Tunability:280-330 nm Upper level life time: 30 ns Saturation fluence:115 mJ/cm 2 Allows optical pumping at 266 nm and 261.75 nm (Nd:YAG or Nd:YLF IV harmonic) Ce:LiCaAlF 6 Ce:LiLuF 4 Tunability:305-340 nm Upper level life time:39 ns Saturation fluence: 50 mJ/cm 2 @ 325 nm Allows optical pumping at 248 nm(KrF excimer laser) Application fields Medical : new compact UV laser sources for surgical applications, no longer requiring the use of toxic gases, such as the excimer lasers employed at present Environmental : systems for the detection of atmospheric components such as SO 2 and O 3 Life sciences : systems for fluorescence diagnostics, with tunable excitation Output coupler, flat, R=60% End mirror, r =200 cm R=100% @ 290 nm, T=85% @ 266 nm Ce:LiCAF f=60 cm 17 cm Pump beam E 10 mJ, t=5 ns E 1 mJ t=4.6 ns FWHM Fluence at the crystal surface 0.8 J/cm 2 Superstable cavity without spectral selection Tunable cavity Output coupler, flat, R=60% Ce:Licaf f=60 cm 19 cm Pump beam (E p =5.8 mJ) E 0.2 mJ End mirror, flat R=100% @ 290 nm, T=85% @ 266 nm 3.5 cm Quartz prism, Brewster/Brewster Max output energy. 200 J @ 289 nm Tuning range : 283.8 nm - 291.0 nm Linewidth 0.3 nm Solid state laser system composed by : - Frequency doubled, diode pumped Nd:YLF laser - Fourth harmonic generation in BBO crystal - Ce:LiCAF laser oscillator Preliminary results - Laser pumping Scientific targets Study and development of new laser sources based on wide band gap crystal with Cerium-ion doping, featuring tunable emission in the near UV. Two main research lines: Development of all solid state devices with laser pumping (Nd:YAG or Nd:YLF laser fourth harmonic ), based on Ce:LiCaAlF 6, tunable between 280-305 nm, and in particular: - Lasers with high pulse repetition rate (several kHz) and low pulse energy - Lasers with low pulse repetition rate (10-30 Hz), high pulse energy - Amplifier for ultrashort pulses (100 fsec) seeded from a Ti:Sapphire laser Development of flashlamp-pumped lasers based on Ce:LiLuF 4 at low pulse repetition rate, tunable between 305 and 340 nm. This aim needs the development of some pre-requisites: - Innovative flashlamps, with short pulse duration and high UV emission - Growth of high quality, large size Ce:LiLuF 4 crystal rods - Reflector with high UV efficiency for the lamp-crystal coupling First results - Xe flashlamps Short-pulse gas discharge flashlamps filled with Xe at subatmospheric pressure are currently under development. When excited with submicrosecond current pulses, Xe exhibits a spectrum with a substantial UV emission, and a fairly good matching with the absorption spectrum of Ce:LiLuF (see graph). At present, emission energies around 100 mJ and pulse durations of few hundreds of ns can be achieved. Other gases (Ar, XeBr excimer) are also under study ULTRAVIOLET SOLID STATE LASER SOURCES M. Vannini a, G. Toci a, D. Alderighi a, M. Tonelli b,A. Piegari c (a) IFAC-CNR, Firenze; (b) Physics Dept., Pisa University; (c) ENEA-Casaccia Research Center, Roma Corresponding author: M. Vannini, IFAC-CNR, V. Madonna del Piano 50019 Sesto F.no, Firenze. E-mail: M.Vannini@ifac.cnr.it