Renpeng Yan

456-nm deep-blue laser generation by intracavity frequency doubling of Nd:GdVO4 under 879-nm diode pumping

We report on a simple, compact continuous-wave 456-nm laser by intracavity frequency doubling of an end-pumped Nd:GdVO4 laser on the 4F3/2 → 4I9/2 transition. A 5-mm-long, 0.2-at % Nd:GdVO4 bulk crystal is employed as the gain medium and the Nd3+ ion is directly pumped into the emitting level (4F3/2) by a novel 879-nm laser diode. Intracavity frequency doubling with a 15-mm-long LBO crystal and a 10-mm-long BiBO crystal in a linear cavity yield 56- and 118-mW single-ended blue outputs at the absorbed pump power of 11.9 W, respectively. The corresponding values are scaled to 286 and 391 mW, respectively, in a V-type cavity, with optical conversion efficiencies of 2.4 and 3.3% versus the absorbed pump power. The fluctuations of the 456-nm output power for both cases are less than 3% at the maximum output level.

12.0-W continuous-wave diode-end-pumped Nd:GdVO 4 laser with high brightness operating at 912-nm

We present a diode-pumped high-power continuous-wave (cw) laser at 912 nm based on the quasi-three-level (4)F(3/2)-->(4)4I(9/2) transition in Nd:GdVO(4) crystal. By using a 5-mm-long conventional bulk crystal with 0.2at.% Nd(3+)-doped concentration, the maximum output power of 12.0 W is obtained, with a slope efficiency of 29.3%. To the best of our knowledge, this is the highest output at 912 nm generated by diode-pumped Nd:GdVO(4) lasers. Furthermore, 3.2 W 456 nm deep-blue light is acquired by frequency doubling, resulting in an optical-to-optical efficiency of 8.0%. The short-term power instability of the blue laser is less than 3%.

High-repetition-rate, high-peak-power, linear-polarized 473 nm Nd:YAG/BiBO blue laser by extracavity frequency doubling

We report on a high-repetition-rate, high-peak-power, linear-polarized 473 nm blue laser. A high-power 946 nm fundamental laser was obtained based on a diode-pumped acousto-optically (AO) Q-switched Nd:YAG laser using a thermal-compensating resonator and a microchannel heat sink for thermal dissipation. A pulsed 473 nm laser was generated using a BiB(3)O(6) (BiBO) crystal as an extracavity frequency doubler. The highest peak power of a 16.7 kW blue laser was obtained at a pulse repetition rate of 10 kHz with a pulse width of 9 ns. Stable operation of the pulsed blue laser can even reach 50 kHz.

8.9-W continuous-wave, diode-end-pumped all-solid-state Nd:YVO4 laser operating at 914 nm

A high power laser-diode-array end-pumped 0.2 at % Nd:YVO4 continuous-wave (CW) laser operating at 914 nm is reported in this letter. The maximum output power of 8.9 W was obtained at the incident pump power of 48.0 W, giving the corresponding optical efficiency of 18.5% and the average slope efficiency of 25.7%. The beam quality factor was measured to be M2 = 2.71 at the output power of 8.0 W by the traveling knife-edge method.

Multiple-beam, pulse-burst, passively Q-switched ceramic Nd:YAG laser under micro-lens array pumping

A novel four-beam (named laserI, laser II, laser III and laser IV, respectively), passively Q-switched, pulse-burst ceramic Nd:YAG laser under 2 × 2 micro-lens array pumping was demonstrated for the purpose of laser-induced plasma ignition (LIPI). Multiple-beam output together with pulse-burst mode in which both high repetition rate and high pulse energy can be realized simultaneously were obtained to greatly improve the performance of LIPI. The pulse-burst contained a maximum of 5 pulses, 3 pulses, 2 pulses and 3 pulses for laserI, laser II, laser III and laser IV, respectively, and the corresponding repetition rate of laser pulses in pulse-burst was 10.8 kHz, 7.2 kHz, 6.8 kHz and 5.2 kHz, respectively. The output energy for single laser pulse in pulse-burst was in the range of 0.12 mJ to 0.22 mJ.

A novel miniaturized passively Q-switched pulse-burst laser for engine ignition

A novel miniaturized Cr⁴⁺:YAG passively Q-switched Nd:YAG pulse-burst laser under 808 nm diode-laser pulse-pumping was demonstrated for the purpose of laser-induced plasma ignition, in which pulse-burst mode can realize both high repetition rate and high pulse energy simultaneously in a short period. Side-pumping configuration and two different types of laser cavities were employed. The pumping pulse width was constant at 250 μs. For the plane-plane cavity, the output beam profile was flat-top Gaussian and the measured M² value was 4.1 at the maximum incident pump energy of 600 mJ. The pulse-burst laser contained a maximum of 8 pulses, 7 pulses and 6 pulses for pulse-burst repetition rate of 10 Hz, 50 Hz and 100 Hz, respectively. The energy obtained was 15.5 mJ, 14.9 mJ and 13.9 mJ per pulse for pulse-burst repetition rate of 10 Hz, 50 Hz and 100 Hz, respectively. The maximum repetition rate of laser pulses in pulse-burst was 34.6 kHz for 8 pulses at the incident pump energy of 600 mJ and the single pulse width was 13.3 ns. The thermal lensing effect of Nd:YAG rod was investigated, and an plane-convex cavity was adopted to compensate the thermal lensing effect of Nd:YAG rod and improve the mode matching. For the plane-convex cavity, the output beam profile was quasi-Gaussian and the measured M2 value was 2.2 at the incident pump energy of 600 mJ. The output energy was 10.6 mJ per pulse for pulse-burst repetition rate of 100 Hz. The maximum repetition rate of laser pulses in pulse-burst was 27.4 kHz for 6 pulses at the incident pump energy of 600 mJ and the single pulse width was 14.2 ns. The experimental results showed that this pulse-burst laser can produce high repetition rate (>20 kHz) and high pulse energy (>10 mJ) simultaneously in a short period for both two different cavities.

Laser properties of continuous-grown Nd:GdVO4/GdVO4 and Nd:YVO4/YVO4 composite crystals under direct pumping

We present the laser properties of continuous-grown Nd:GdVO(4)/GdVO(4) and Nd:YVO(4)/YVO(4) composite crystals under LD direct pumping . The maximum CW output powers of 20W with a slope efficiency of 74.9% to absorbed pump power and 32W with 82.7% were obtained in Nd:GdVO(4)/GdVO(4) and Nd:YVO(4)/YVO(4) lasers, respectively. To our knowledge, this is the highest slope efficiency obtained in Nd(3+) lasers. Furthermore, at the repetition rate of 100 kHz, the minimum pulse width of 15.0 ns and 12.9 ns, the peak power of 11.8 kW and 22.4 kW were obtained for Nd:GdVO(4)/GdVO(4) and Nd:YVO(4)/YVO(4) lasers, respectively.

Comparison on performance of acousto-optically Q-switched Nd:GdVO 4 and Nd:YVO 4 lasers at high repetition rates under direct diode pumping of the emitting level

We detail the comparison on laser performance of Nd:GdVO(4) and Nd:YVO(4) lasers at high repetition rates operated at 1.06 microm under direct diode pumping of the upper laser level. The results reveal that Nd:GdVO(4) and Nd:YVO(4) are efficient laser crystals for solid-state lasers under direct pumping of the emitting level. However, Nd:YVO(4) crystal, compared with Nd:GdVO(4) crystal, is a more favorable gain medium when higher repetition rates and shorter pulse width are desired, owning to its larger stimulated emission cross-section.

High repetition rate, high peak power acousto-optical Q-switched 946 nm Nd:YAG laser

A diode-end-pumped high repetition rate, high peak power acousto-optical (AO) Q-switched 946 nm Nd:YAG laser was demonstrated in this paper. In our experiments, a 20 mm miniature acousto-optical Q-switch was employed in a 45 mm linear laser cavity for generating the short laser pulse. At a repetition rate of 10 kHz, a maximum average output power of 2.9 W was achieved with a pulse width of 24.4 ns, giving a peak power of 11.9 kW. To the best of our knowledge, this is the highest peak power 946 nm Nd:YAG laser at high repetition rate operation. Moreover, pulse train with good stability was also obtained at the repetition rate of 50 kHz. At an incident pump power of 22.3 W, up to an average output power of 3.5 W pulsed 946 nm laser was generated at 50 kHz with a pulse width of 69 ns, corresponding to an optical conversion efficiency of 15.7% and an average slope efficiency of 24.1%, respectively.

Power scaling of directly dual-end-pumped Nd:GdVO 4 laser using grown-together composite crystal

Power scaling of end-pumped Nd:GdVO(4) laser was realized by direct pumping, grown-together composite crystal and dual-end-pumping. A maximum CW output power of 46.0W with M(2)<1.1 was achieved, corresponding to a slope efficiency of 71.1% to absorbed pump power. In A-O Q-switch operation, peak power of 304.1kW, 58.6kW and 23.8kW, pulse width of 7.2ns, 11.3ns and 16.2ns were obtained at the repetition rates of 10kHz, 50kHz and 100kHz, respectively.