Periodical switching laser pulses with nanosecond pulse width and several kilowatts peak power from wideseparated multilongitudinal-mode oscillation were observed experimentally in laser-diode pumped passively Q-

In single crystals of the beryllium silicate Be 2 SiO 4 with trigonal symmetry R3, known also as the mineral phenakite, χ (3) -nonlinear lasing by stimulated Raman scattering (SRS) is investigated. All observed Stokes and anti-Stokes lasing components are identified and ascribed to a single SRS-promoting vibration mode with ω SRS ≈876 cm −1 . With picosecond singlewavelength pumping at one micrometer the generation of an octave-spanning Stokes and anti-Stokes comb is observed.Al 2 [F 1-x (OH) x ] 2 SiO 4 four different SRS-promoting modes were observed, two of which are combined modes. These occurring differences in nonlinear-lasing characteristics motivated the present study of SRS in Be 2 SiO 4 (phenakite). The crystal structure of phenakite gives a simple example of an intermediate link between neso-silicates and tectosilicates, since all (mutually separated) [SiO 4 ] groups of the structure are strongly bonded by tetrahedral [BeO 4 ] structural units to form a three-dimensional framework [7-10]. CrystallographyBeryllium silicate, Be 2 SiO 4 , also known as the (rare) mineral phenakite, is a member of a family of isostructural trigonal compounds of general composition M 2 XO 4 , which crystallize with space group symmetry R3 (Nr. 148). In this structural family representatives are known with M II and X IV (e.g. Be ) and with M III and X II (e.g. Al 2 CdO 4 ). Coupled substitution of 2M II → M I + M III (with X IV ) or 2M II → M I + M II (with X V ) allows C

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We study stimulated Raman scattering (SRS) and Raman four-wave mixing (RFWM) processes in chemical vapour deposition (CVD) diamond crystals. The strong interaction of picosecond laser pulses at 1.064 and 0.532 µm wavelength with the dominant Raman-active F 2g mode results in a more than two-octave-spanning frequency comb, ranging from the UV to the NIR spectral region. In addition to spectroscopic analysis of the χ (3) -nonlinear emission at room temperature, comparative measurements have been carried out at cryogenic temperature of 10 K. The Raman shift and the Raman gain are found to change only weakly. Moreover, the potential of SRS frequency comb generation in CVD diamond for ultra-short pulse synthesis is discussed.

We present cw and mode-locked laser operations on the base of partially disordered crystalline Yb(3+):{YGd(2)}[Sc(2)](Al(2)Ga)O(12) ceramics. In continuous-wave laser operations, the average power of 2.9 W at the wavelength of 1051 nm and 2.8 W at the wavelength of 1031 nm with above 40% optical-to-optical efficiencies were achieved. In mode-locked laser operation, pulses as short as 69 fs with the average power of 820 mW was also obtained.