B. Z. Li

Triggering and guiding high-voltage discharge in air by single and multiple femtosecond filaments.

The abilities to trigger and guide high-voltage discharge by using single and <em>multiple filaments</em> (MFs) are experimentally studied. It is shown that the discharge voltage threshold can be reduced significantly in both regimes of single and MF; however, the MF does not gain a larger reduction than a single filament. This behavior of the MF is attributed to the single discharge path rather than simultaneous multiple ones as one might expect during the discharge process.

Light absorption enhancement in thin-film solar cells by embedded lossless silica nanoparticles

Embedded silica nanoparticles in thin-film silicon solar cells have some advantages over metal nanoparticles in enhancing optical absorption of silicon such as no loss, better compatibility with antireflection coating and extremely low dangling bond densities and interface recombination velocities. To the best of our knowledge, we have carried out the first systematic study of optical absorption enhancement with silica nanoparticles of different radii, array periods and depths in the silica substrate with the finite-difference time-domain method, and we have obtained the optimum values of the nanoparticle parameters. We discuss the physical mechanism of the optical absorption enhancement in detail and attribute the enhancement to the superposition of the particle scattering effect and the Fabry–Perot resonance effect.

Continuous-wave dual-wavelength operation of a diode-end-pumped Nd:GGG laser

A dual-wavelength continuous-wave (CW) diode-pumped Nd:LuVO4 laser that generates simultaneous laser action at the wavelengths 1066 and 1343 nm is demonstrated. A total dual-wavelength output power of 2.58 W was achieved at the incident pump power of 18.2 W. Furthermore, intracavity sum-frequency mixing at 1066 and 1343 nm was then realized in a LBO crystal to reach the yellow range. We obtained a total CW yellow output power of 830 mW at 594 nm.

Optical absorption enhancement in solar cells with cylindrical Ag nanoparticles by localized surface plasmons

The use of nanoparticles on thin-film solar cells is an effective way to enhance optical absorption. A simulation is presented of a three-dimensional array of cylindrical Ag nanoparticles on the surface of a solar cell, which has been proved very efficient to enhance the optical absorption of the silicon substrate by utilizing localized surface plasmons. The enhancement ratio has been simulated with respect to nanoparticle radius and height as well as crystalline silicon substrate thickness and is discussed in detail. The absorption enhancements were found to exhibit a damping oscillation when only height or thickness of the cylindrical nanoparticle were varied. Even without intentional optimization, an enhancement factor of 1.283 for a silicon substrate with a thickness of 500 nm was still achieved in our simulations. A further optimized structure has the potential to attain a higher factor.

Diode-pumped Nd:YVO4-LBO laser at 544 nm based on intracavity sum frequency generation

A dual-wavelength continuous-wave (CW) diode-pumped Nd:YVO4 laser that generates simultaneous laser action at the wavelengths 914 and 1342 nm is demonstrated. A total dual-wavelength output power of 1.79 W was achieved at the incident pump power of 18.2 W. Furthermore, intracavity sum-frequency mixing at 914 and 1342 nm was then realized in a LBO crystal to reach the yellow-green range. We obtained a total CW output power of 212 mW at 544 nm.

All-solid-state Nd:YAG-LBO yellow laser at 572 nm

We report for the first time a continuous-wave (CW) yellow laser emission by sum-frequency mixing in Nd:YAG crystal. Using type-I critical phase-matching LBO crystal, a yellow laser at 572 nm is obtained by 1444 and 946 nm intracavity sum-frequency mixing. The maximum laser output power of 178 mW is obtained when an incident pump laser of 18.2 W is used. At the output power level of 178 mW, the output stability is better than 4.2%.

Efficient CW Yb:YAG laser at 1048 nm under 968 nm diode laser pumping

We describe the output performances of the 1048 nm transition in Yb:YAG under in-band pumping with diode laser at the 968 nm wavelength. An end-pumped Yb:YAG crystal yielded 787 mW of continuous-wave (CW) output power for 9.1 W of absorbed pump power. Furthermore, 104 mW 524 nm green light was acquired by frequency doubling. Comparative results obtained for the pump with diode laser at 940 nm are given in order to prove the advantages of the in-band pumping.

Diode-pumped Nd:YVO4 intracavity-doubled red laser at 693 nm

It is reported that efficient continuous-wave (CW) red laser generation at 693 nm in a LBO crystal at type-I phase matching direction performed with a diode-pumped Nd:YVO4 laser. With incident pump power of 18.2 W, output power of 278 mW at 693 nm has been obtained using a 10 mm-long LBO crystal. At the output power level of 278 mW, the output stability is better than 2.9%.

Simultaneous dual-wavelength CW laser operation at 1064 and 930 nm in Nd3+:YAlO3

A dual-wavelength continuous-wave (CW) diode end-pumped Nd3+:YAlO3 (Nd:YAP) laser that generates simultaneous laser action at the wavelengths 1064 and 930 nm is demonstrated. A total output power of 2.15 W (1.57 W at 1064 nm and 0.58 W at 930 nm) for the dual-wavelength was achieved at the incident pump power of 17.8 W with optical conversion efficiency of 12.1%. The M2 values for 930 and 1064 nm lights were found to be around 1.21 and 1.32, respectively.

Diode-pumped Nd:LGS laser emitting at 888 nm

We present what is, to the best of our knowledge, the first diode-pumped Nd:La3Ga5SiO14 (Nd:LGS) laser emitting at 888 nm, based on the 4F3/2-4I9/2 transition, generally used for a 904 nm emission. The use of a pump module with 16 passes through the crystal allowed the realization of a Nd:LGS thin-disk laser with 1.41 W of continuous wave (cw) output power at 888 nm. Moreover, intracavity second-harmonic generation (SHG) in cw mode has also been demonstrated with a power of 221 mW at 444 nm by using a BiB3O6 (BiBO) nonlinear crystal.