Nanoparticles synthesis using supercritical fluid technology - towards biomedical applications.

After a brief examination of known insulating laser crystals and the stimulated emission channels of their generating activator ions, this article reviews recent advances in the development of novel lasing crystals and ceramics, as well as inorganic and organic nonlinear-laser crystals for χ(3) and cascaded χ(3) ↔ χ(2) frequency converters Several new modern attractive technologies in the physics and techniques of crystalline lasers are also discussed

https://onlinelibrary.wiley.com/doi/pdf/10.1002/lpor.200710008

Laser crystals and ceramics: recent advances

2-μm lasers with fluoride crystals: Research and development

We report the first demonstration, to our knowledge, of passive Q-switched mode-locking in a Tm3+:YAP laser, operating in the 2 μm broadly spectral region formed with a compact Z-flod cavity. A transmission-type single-walled carbon nanotube saturable absorber (SWCNT–SA) is used for the initiation of the pulse generation. The repetition rate of the Q-switched envelope was 60 kHz at the pump power of 8.6 W. The mode-locked pulses inside the Q-switched pulse envelope had a repetition rate of ∼92 MHz. A maximum average output power of 761 mW was obtained. The dependence of the operational parameters on the pump power was also investigated experimentally.

2 μm passive Q-switched mode-locked Tm3+:YAP laser with single-walled carbon nanotube absorber

A comparison of Tm,Ho:YLF; Tm,Ho:LuLF; and Tm,Ho:LuAG crystals under identical experimental conditions showed that Tm,Ho:LuLF yielded significantly better performance. The thermal expansion coefficients were measured. These crystals were experimentally characterized in the spectral region of 680 nm and 780 nm accessible to laser diodes. The effective energy storage lifetimes of the Ho 5I7 manifold at room temperature were measured experimentally. At 10 Hz and 273 K, free-running laser output energy in excess of 17 mJ was obtained in Tm,Ho:YLF compared with 30 mJ in Tm,Ho:LuLF and 24.4 mJ in Tm,Ho:LuAG. The slope efficiencies with respect to the incident pump energy were 7.4%, 12.9%, and 11.6%, respectively. The temperature dependence of the output energies of these lasers was investigated.

Spectroscopic and diode-pumped-laser properties of TM,Ho:YLF; Tm, Ho:LuLF; and Tm,Ho:LuAG crystals: a comparative study

Lasing in diode-pumped Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF

YAP versus YAG as a diode-pumped host for thulium

We report the successful picosecond laser welding of AlSi and YAG. This material combination is of significant interest to the field of laser design and construction. Parameter maps are presented that demonstrate the impact of pulse energy and focal position on the resultant weld. Weld performance relevant to industrial applications is measured, i.e., shear strength, process yield, and absolute thermal resistance are presented.

Picosecond laser microwelding of AlSi-YAG for laser system assembly.

Ultrafast laser welding, hydroxide catalysis bonding (HCB) and adhesive bonding techniques were used to bond N-BK7 cubes to aluminum bases. Using a thermal chamber and polariscope, the stress induced birefringence was measured at temperatures from -50°C to +80°C. Adhesive samples made with different industrial assembly methods were compared for thermal birefringent behavior. An ultrafast laser welded sample was thermally cycled in increasing temperature ranges, surviving the test with reduced retardation, indicating fatigue. An HCB sample was thermally cycled like the laser welded sample, and had a linear birefringent relation to temperature initially, and failed by fatigue after a fracture event. 

Birefringence analysis of aluminum-to-BK7 glass bonding methods under thermal stress

High pulse energy, low-alignment sensitivity master-oscillator power-amplifier (MOPA) systems enable portable long range laser devices. Comprehensive amplifier modelling is an essential tool in producing efficient, optimised amplfication capable of producing high pulse energies. This paper outlines the development of a large-mode, low-alignment sensitivity neodymium yttrium aluminium garnet (Nd:YAG) (MOPA) system, achieving a total output pulse energy of 265 mJ with an optical efficiency of 18%. A Q-switched diode-pumped Nd:YAG zig-zag oscillator is developed with an output pulse energy of 98 mJ and slope efficiency of 31%. Through the use of an intracavity aperture, the beam quality exhibited an M2 of 4.3 and 4.6 and far field divergence of 1.3 mrad and 1.2 mrad in the horizontal and vertical, respectively. The oscillator output is amplified within a diode-pumped Nd:YAG zig-zag amplifier with a system amplification of 2.8. Comprehensive amplifier modelling based on a Frantz-Nodvik analysis is demonstrated, with the saturation characteristics suggesting a route to further energy enhancement and highlighting the necessity for amplifier modelling in high energy system design.

I.F Elder

Papers

Lasing in diode-pumped Tm:YAP, Tm,Ho:YAP and Tm,Ho:YLF

YAP versus YAG as a diode-pumped host for thulium

Picosecond laser microwelding of AlSi-YAG for laser system assembly.

Birefringence analysis of aluminum-to-BK7 glass bonding methods under thermal stress

High-energy Q-switched Nd:YAG oscillator and amplifier development for large-mode, low-alignment sensitivity applications