Ruiping Cheng

Growth and laser properties of Nd:Ca4YO(BO3)3 crystal

Abstract Nd:Ca 4 YO(BO 3 ) 3 (Nd:YCOB) crystal was grown by the Czochralski method, and its structure was measured by using a four circle X-ray diffractometer. The transparent spectrum from 200 to 2600 nm was measured at room temperature. The fluorescence spectrum near 1.06 μm showed that the main emission wavelength of Nd:YCOB crystal was centered at 1060.8 nm. Laser output at 1.06 μm has been demonstrated when it was pumped by a Ti:sapphire laser at the wavelength of 794 nm, the highest output power was 68 mW under pumping power of 311 mW, the pumping threshold was 163 mW and slope efficiency was 46.9%. The self-frequency doubled green light has been observed when it was pumped by a Ti:sapphire or a laser diode (LD). A 14.5 mm Nd:YCOB crystal sample cut at ( θ , φ )=(90°, 33°) was used for type I second-frequency generation (SHG) of the 1.06 μm laser pulse. The SHG conversion efficiency was 22%.

Growth and thermal properties of Yb:Ca4YO(BO3)3 crystal

Abstract Yb:Ca4YO(BO3)3 (Yb:YCOB) crystal of good quality and large size has been grown by the Czochralski method. The thermal expansion and specific heat have been measured. The thermal expansion coefficients along X, Y and Z axes are 12.0×10−6/K, 3.3×10−6/K and 6.6×10−6/K, respectively. The specific heat is 79.5 cal/mol K at 330 K.

Investigation of LD end-pumped Nd:YVO4 crystals with various doping levels and lengths

Abstract The absorption properties of Nd:YVO4 crystals with various doping levels and lengths are reported. The effective stimulated emission cross-sections of different doping levels are calculated with measured upper-level lifetimes. Our investigation gives good advice on the optimization of LD end-pumped Nd:YVO4 laser.

Growth, Stark energy level and laser properties of Yb:Ca4YO(Bo3)3 crystal

Abstract Yb:Ca 4 YO(BO 3 ) 3 (Yb:YCOB) crystal was grown by the Czochralski method. The polarization absorption and fluorescence spectra were measured. The Stark energy level was determined based on the absorption and fluorescence spectra. When pumped by a laser diode (LD) at 976.4 nm, the output laser at 1032 nm was demonstrated.

Improving beam profile of LD-Pumped self-frequency-doubled NYAB laser

By means of studding on the characteristics of phase mismatch of Neodymium yttrium aluminum borate [NdxY1-xAl(BO3)4; NYAB] crystal, a method of improving beam profile of NYAB laser was presented. Because of the exist of little, periodically local shortcomings of NYAB crystal, there were different wave-vector mismatch (Delta) Ks at the different locations of NYAB when a wide incident beam passed through it for SHG. According to the phase matching theory of second harmonic generation, there were different conversion efficiencies at the different locations of the incident beam, resulting in inhomogeneous beam profile of second harmonics. We measured the curves of the SHG efficiencies versus phase mismatch angles of NYAB crystals under cases of different diameters (100 micrometers - 2 mm) of fundamental wave beam. The curves showed that the phase mismatch acceptance angle (Delta) (Theta) m was very small for the thin incident beam when a very homogeneous harmonic beam was obtained, while (Delta) (Theta) m was large for a wide incident beam and the profile of the harmonic beam was not homogeneous.