Zhenlin Liu

Crystal growth of Ce : LiLuF4 for optical applications

Abstract High-quality Cexa0:xa0LiLuF 4 (Cexa0:xa0LLF) crystals were grown by the Czochralski technique using CF 4 as reactive atmosphere. The segregation coefficient of Ce 3+ was determined to be 0.066 (3). No changes in the lattice parameters due to the presence of the Ce 3+ in the lattice were observed. Laser action in the ultraviolet region was obtained by pumping this active medium with a KrF excimer laser in 248xa0nm.

Observation of new excitation channel of cerium ion through highly vacuum ultraviolet transparent LiCAF host crystal

Abstract The transmission spectra of LiCaAlF 6 (LiCAF) and LiSrAlF 6 (LiSAF) are investigated in the ultraviolet (UV) and the vacuum ultraviolet (VUV) region. The transmission edge of LiCAF (112xa0nm) shows almost the same value as that of LiF. Taking into account difficulties of material processing and polishing due to the cleavage or the hydroscopic nature of LiF, LiCAF is regarded as a more suitable optical material in the UV and the VUV region. Moreover, the new excitation channel around 112xa0nm is discovered for Cexa0:xa0LiCAF crystal. This excitation is originated not from absorption of Cerium ions but from absorption around the bandgap of the host crystal.

High-energy pulse generation from solid-state ultraviolet lasers using large Ce:fluoride crystals

Abstract A large Ce3+:LiCaAlF6 (Ce:LiCAF) crystal with 15 mm diameter was grown successfully by the Czochralski method. Owing to its large size, 60 mJ, 289 nm pulses were generated directly from a quasi-coaxially pumped Ce:LiCAF laser. In addition, a new noncollinear Brewster-angle-pumping disk oscillator scheme was demonstrated for further output-energy scaling. An ultraviolet solid-state Ce3+:LiLuF4 (Ce:LLF) laser which was pumped transversely by a KrF excimer laser with the repetition rate of 1 Hz produced a 27 mJ, 309 nm pulse using a large Ce:LLF crystal which was grown by the Czochralski method, and the slope efficiency was approximately 17%.

Growth and laser performance of Ce-doped LiCaAlF 6 and LiSr 0.8 Ca 0.2 AIF 6 single crystals for UV laser applications

Ce-doped LiCAF (Ce:LiCAF), LiSrAlF6 (Ce:LiSAF) and LiSr0.8Ca0.2AlF6 (Ce:LiSCAF) single crystals were grown by the Czochralski technique as ultraviolet, tunable, solid- state laser media. Optical characterization and Laser activity were investigated. Crystal growth was performed in Czochralski system (CZ) under an atmosphere of CF4 with previous treatment in high vacuum (approximately equals 10-2 Pa). Under such conditions, we succeeded to grow Ce:LiCAF, Ce:LiSAF and Ce:LiSCAlF (18 mm in diameter and 60 mm in length) single crystals. Laser rods were cut from the above mentioned crystal boules. The laser resonator was established by a flat high reflector and a flat output coupler. The forth harmonic of a Q-switched Nd:YAG laser was used as the pumping source. Laser oscillations at around 290 nm were measured. 60 mJ pulses were generated directly from the Ce:LiCAF crystal. Gain has been observed for the Ce:LiSCAlF crystal and laser oscillation was confirmed.

High-average power mode-locked Ti:sapphire laser with newly-invented intra-cavity cm-amplification scheme

We have demonstrated high-average power mode-locked Ti:sapphire laser with newly-invented intra-cavity cw-amplification scheme. This scheme can be applicable for the power scaling of other lasers.

High-pulse-energy ultraviolet Ce:LLF and Ce:LiCAF lasers using CZ-grown large-size crystals and new cavity configuration

Summary form only given. Ce/sup 3+/:LiCaAlF/sub 6/ (Ce:LiCAF) and Ce/sup 3+/:LiLuF/sub 4/ (Ce:LLF) have been identified to be efficient and convenient ultraviolet (UV) lasing media. We have demonstrated an all-solid-state tunable Ce:LLF laser pumped by the fifth harmonic of an Nd:YAG laser. We have also demonstrated an efficient Ce:LiCAF MOPA system. Previously, the output energy was limited by available crystal sizes. Therefore, we grow larger crystals up to about 1-inch diameter by Czochralski (CZ) method. In this presentation, we report the generation of 27-mJ pulse from a Ce:LLF oscillator and 60-mJ pulse from a Ce:LiCAF oscillator using large-size Ce:fluoride crystals. Furthermore, a new pumping configuration with pumping at Brewster angles on the disk-shaped crystal was designed.

Tunable ultraviolet solid-state lasers using large Ce:fluoride crystals and new pumping scheme

Using (Czochralski) CZ-grown large laser crystals, 60-mJ pulses and 27-mJ pulses were obtained from Ce:LiCaAlF/sub 6/ (Ce:LiCAF) and Ce:LiLuF/sub 4/ (Ce:LLF) lasers. Additionally, a new non-collinear Brewster-pumping disk Ce:LiCAF laser oscillator scheme was demonstrated for further output-energy scaling.