Longsheng Qian

High-power high-repetition-rate UV light at 355 nm generated by a diode-end-pumped passively Q -switched Nd:YAG laser

We describe experimental results with a diode-pumped, passively Q-switched extracavity second- and third-harmonic generation. Cr:YAG is used as a saturable absorber for pulse generation. Taking into account the thermal effects of Nd:YAG at high incident pump power, we use a short plane-to-plane cavity configuration to take advantage of the maximum pump power and obtain the compactness structure. At the same time, we use the type-I critical phase-matched lithium triborate crystal to generate light at 532 nm and mix the residual fundamental at 1064 nm and the second-harmonic wave at 532 nm in the type-II critical phase-matched lithium triborate crystal for UV light generation at 355 nm. A third-harmonic-generation output power of 1.32 W is achieved at the incident pump power of 27.5 W, corresponding to an optical-to-optical efficiency of 4.8%. The instability of the UV laser power is less than 5% for 4 h.

Diode-pumped 671 nm laser frequency doubled by CPM LBO

Abstract A design of diode-pumped high-efficiency Nd:YVO4/LBO red laser is reported. Using critical phase-matching (CPM) LBO, 671 nm red laser was obtained from 1342 nm light by intracavity frequency doubling. With an incident pump laser of 800 mW , using type-I and type-II CPM LBO, 97 and 52 mW TEM 00 mode red laser outputs were obtained, with optical-to-optical conversion efficiencies of up to 12.1% and 6.5%, respectively.

LD-pumped single-frequency passively Q-switched green laser

Abstract A LD-pumped single-frequency passively Q-switched Nd: YVO4/KTP/Cr:YAG green laser is presented. Cr:YAG plays the double role of a passive Q-switch and a Brewster plate. With 900 mW incident pump laser, single-frequency passively Q-switched green laser with average power of 86 mW , pulse width of 14.7 ns , repetition rate of 140.8 kHz and peak power of 41.6 W is obtained. Measurement shows that the pulse amplitude and period between pulses are stable within ±1.5%.

Growth of segmented ZnS nanocones induced by regular occurrence of twins structure

Segmented ZnS nanocones have been prepared at 1200 degrees C by thermal evaporation of zinc sulfide powders and catalyst metal tin. The as-synthesized products have been studied by energy-dispersive x-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. Microstructure characterization indicates that the formation of segmented nanocones can be attributed to the effects of regular twins structure. Theoretical analysis reveals that the nonuniform cross sections of nanocones are related to the continuous change of Sn-ZnS liquid droplets scale resulting from the supply of Sn atoms during the evaporation. According to microstructure characterization and dimension analysis, the potential formation mechanism of the segmented ZnS nanocones was discussed

Optical thin films for high power LD-pumped Nd: YVO 4 457 nm blue laser

The expanding field of LD-pumped solid state lasers forms an extraordinary challenge for developing the optical coatings. Optical thin films for LD-pumped Nd:YVO4/LBO blue laser at 457nm was presented in this paper based on lower gain laser line action theory, including spectral beam dividers and doubling antireflecting multilayer coatings. To achieve 914nm laser action and 457nm blue light high output power, the coating specifications of laser resonator was analyzed. The transmittance/reflectance spectrum request was effectively separated by adopting high tuned radio stack, simultaneously the spectrum request was reasonably distributed on the two resonator facet reflectivity for restrain the other laser lines such as 1064nm and 1342nm. The dielectric high reflective laser mirror and antireflecting coatings for 457nm laser were manufactured by double ion beam sputtering technique, which is controlled by a time-power monitoring. Using type-I critical phase-matching LBO crystal, 457nm blue laser is obtained by 914nm intracavity frequency doubling. The maximum laser output power of 1.5W is obtained when incident pump laser of 15W is used.

1.41 W Nd: YAG laser at 556 nm end-pumped by laser diode arrays

A Nd: YAG laser has longitudinally pumped by a fiber coupling 20 W laser diode array with emission wavelength at 808nm in a three folded cavity configuration. After a 150 μm thickness etalon was inserted into the cavity, the 1112nm fundamental laser operation was obtained, and then intracavity-frequency-doubling with a LBO crystal produced 1.41W of stable output at 556nm.

LD-pumped all-solid-stated green laser with high polarization rate and high conversion efficiency

A high-power-output and high polarization rate Nd:YVO4/KTP green laser has been presented. By analyzing the factors which affect the conversion efficiency and polarization rate, we used a short folded-cavity resonator, the maximum output power of 320 mW is obtained at 532 nm with the LD pumping power of 1 W, the optical-to-optical conversion efficiency is 32% and the polarization rate is 550:1.