Baoshan Wang

Compact KTA-based intracavity optical parametric oscillator driven by a passively Q-switched Nd : GdVO4 laser

We present a compact and efficient KTA-based intracavity optical parametric oscillator (IOPO) driven by a diode-end-pumped Nd:GdVO(4)/Cr:YAG passively Q-switched laser. At the incident diode pump power of 9.2 W, signal (1.53 microm) and idler (3.47 microm) average output powers of up to 744 and 356 mW, respectively, have been obtained. The total (signal+idler) optical-to-optical conversion efficiency is as high as 12%. By using the knife-edge method, near-diffraction-limited signal and idler beams have been detected, and the M(2) factors are well within 1.2. In addition, based on the ABCD matrix theory, the impact of mode matching and the thermal lens effect on the OPO output have been analyzed.

Narrow Linewidth 177.3-nm Nanosecond Laser With High Efficiency and High Power

We demonstrate a high-efficiency high average power vacuum ultraviolet (VUV) 177.3-nm laser with a narrow linewidth generated by second harmonic (SH) generation from a nanosecond (ns) 355-nm laser in the KBe2BO3F2 crystal. The 355-nm pumping source was a frequency-tripled Q-switched 1064-nm Nd:YAG oscillator-amplifier laser system, in which a quartz etalon was used to compress the linewidth of 1064-nm laser. Under a pump power of 5.2 W at 355 nm with a linewidth of 2 pm, a high average power of 146.5 mW at 177.3 nm with a linewidth of ~0.71 pm was obtained, corresponding to an SH conversion efficiency as high as 2.8%. This is, to the best of our knowledge, the highest output power and highest SH conversion efficiency for the ns 177.3-nm lasers. This VUV coherent light can be used as light source for fine precision spectroscopy and semiconductor photolithography owing to its narrow linewidth, high energy resolution, and high average power.

High Brightness 556 nm Laser by Frequency Doubling of a 1112 nm Nd:YAG Laser

We demonstrate an efficient high power and high brightness yellow-green 556-nm laser generated from second harmonic generation (SHG) of a master oscillator power amplifier (MOPA) laser system at 1112 nm. The oscillator was a pulsed laser diode (LD) pumped and Q-switched Nd:YAG laser at 1112 nm operated at TEM00 mode with an average output power of 35 W, providing 200-μs long macropulses and constituting 700-ns micropulses. The seed laser was amplified by two LD side-pumped Nd:YAG amplifiers and the MOPA system delivered a maximum output power of 78 W. Using a type-I phase-matching lithium triborate nonlinear crystal, the SHG maximum output power of 48 W was obtained at 556 nm with a conversion efficiency as high as 61.5%. The beam quality factor was measured to be M2 = 1.53 and the corresponding brightness was as high as 6.63 × 109 W/cm2·sr.

High-power narrow-linewidth quasi-CW diode-pumped TEM00 1064 nm Nd:YAG ring laser.

We demonstrated a high average power, narrow-linewidth, quasi-CW diode-pumped Nd:YAG 1064 nm laser with near-diffraction-limited beam quality. A symmetrical three-mirror ring cavity with unidirectional operation elements and an etalon was employed to realize the narrow-linewidth laser output. Two highly efficient laser modules and a 90° quartz rotator for birefringence compensation were used for the high output power. The maximum average output power of 62.5 W with the beam quality factor M(2) of 1.15 was achieved under a pump power of 216 W at a repetition rate of 500 Hz, corresponding to the optical-to-optical conversion efficiency of 28.9%. The linewidth of the laser at the maximum output power was measured to be less than 0.2 GHz.

Simultaneous Q switching and mode locking with narrow envelope width in a microchip Nd:YVO4 laser with a composite semiconductor absorber

By using a composite semiconductor absorber and an output coupler, we demonstrated a Q-switched and mode-locked diode-pumped microchip Nd:YVO4 laser. With a 350-μm-thick crystal, the width of the Q-switched envelope was as short as 12 ns; the repetition rate of the mode-locked pulses inside the Q-switched pulse was more than 10 GHz. The average output power was 335 mW at a maximum pump power of 1.6 W. Q-switched envelope widths of 21 and 31 ns were also achieved with crystals 0.7 and 1.0 mm thick, respectively.

High-power 660.5 nm red laser from diode-side-pumped intracavity frequency-doubled Nd:YLF laser

We demonstrate a high-power red laser at 660.5 nm from intracavity frequency doubling of a diode-side-pumped 1321 nm Nd:LiYF4 (Nd:YLF) ring laser in a LiB3O5 (LBO) crystal. The maximum average output power of the red laser is obtained to be 23 W with beam quality factor M 2 = 1.3.