Zhang Zhi-Guo

Passive mode locking of a Nd:YAG laser with co-doped Nd, Cr:YAG as saturable absorber

We demonstrate the characteristics of relatively low saturation intensity using co-doped Nd, Cr:YAG as saturable absorber for passively mode locking the Nd:YAG laser. The difference of the saturation intensity between Q-switched and mode-locked operation in co-doped Nd, Cr:YAG was only one to two orders of magnitude, while Cr:YAG was generally reported at a difference of five orders of magnitude. More than 80% mode locking modulation depth was achieved at an incident pump power of 4.4W, corresponding to an intracavity intensity of 6×104W/cm2, using a 68cm long plano-concave cavity.

Laser Performance of Nd:GGG Operating at 938 nm

We report an efficient diode-pumped Nd-doped Gadolinium gallium garnet (GGG) continuous-wave (CW) laser operating at 938 nm. Laser action of 1.6at.% Nd-doped GGG crystals with different lengths and temperatures are also investigated. The maximum output power of 620 mW is obtained at the incident pump power of 5.0 W with a slope efficiency of 15%.

Diode-pumped passive Q-switched 946-nm Nd : YAG laser with 2.1-W average output power

We demonstrate a diode-pumped passive Q-switched 946 nm Nd:YAG laser with a diffusion-bonded composite laser rod and a co-doped Nd,Cr:YAG as saturable absorber. The average output power of 2.1 W is generated at an incident pump power of 14.3 W. The peak power of the Q-switched pulse is 643 W with 80 kHz repetition rate and 40.8 ns pulse width. The slope efficiency and optical conversion efficiency are 17.6% and 14.7%, respectively.

Compact diode-pumped continuous-wave Nd : LuVO4 lasers operated at 916 nm and 458 nm

We report the compact diode-pumped continuous-wave (CW) Nd:LuVO4 lasers operated at 916 nm and 458 nm for the first time. The maximum output power of 780 mW at 916 nm laser is obtained with a slope efficiency of 9.3%. We generate 50 mW of 458 nm blue laser employing a type-I critical phase-matched LBO crystal.

Diode-Pumped Self-Q-Switched Cr,Nd:YAG Laser with High Average Output Power

A diode end-pumped self-Q-switched Cr,Nd:YAG laser was established with pulse duration in the range of 8–10 ns. The maximum average output power was 4.4 W and the slope efficiency was 27% using an output coupler of R = 70%. At pumping power of 17.4 W the laser produces high-quality pulses at 1064 nm in a TEM00-mode.

Characteristics of Nd:GdVO4 Laser with Different Nd-Doping Concentrations

We report the properties of a compact diode-pumped continuous wave Nd:GdVO4 laser with a linear cavity and different Nd-doped laser crystals. In a 0.2at.% Nd-doped Nd:GdVO4 laser, 1.54 W output laser power is achieved at 912 nm wavelength with a slope efficiency of 24.8% at an absorbed pump power of 9.4 W. With 0.3at% Nd-doping concentration, we can obtain the either single-wavelength emission at 1064 nm or 912 nm or the dual-wavelength emission at 1064 nm and 912 nm by controlling the incident pump power. From an incident pump power of 11.6 W, the 104 nm emission between F-4(3/2) and I-4(11/2) is suppressed completely by the 912 nm emission between F-4(3/2) and I-4(9/2). We obtain 670 mW output of the 912 nm single-wavelength laser emission with a slope efficiency of 5.5% by taking an incident pump power of 18.4 W. Using a Nd:GdVO4 laser with a 0.4at% Nd-doping concentration, we obtain either the single-wavelength emission at 1064 nm or the dual-wavelength emission at both 1064 nm and 912 by increasing the incident pump power. We observe a strong competition process in the dual-wavelength laser.

Diode-pumped self Q-switched and mode-locking Nd3+Cr4+: YAG laser

Using Nd3+,Cr4+:YAG as a laser crystal and saturable absorber simultaneously, we obtain a self-Q-switched and mode-locking laser at 1.06 μm with straight cavity structure. Self mode-locking phenomenon was observed at an intracavity intensity of only about 2000 W/cm2. More than 90% modulation depth is achieved at an intracavity intensity of less than 3.0×104 W/cm2 for the first time. The Q-switched pulse width and repetition rate are found to be connected with the cavity length and the output power.

Self-mode-locking in a diode-pumped self-Q-switched Nd3+,Cr4+: YAG laser

We report for the first time on the observation of self-mode-locking in a diode pumped self-Q-switched (SQS) Nd3+,Cr4+:YAG laser. This phenomenon results from significant excited state absorption of the Cr4+ ions in the co-doped host during the SQS laser pulses. The self-mode-locking occurs already slightly above the SQS laser threshold. Experiments using relatively low saturable intensity achieved a modulation depth of more than 40%.

Compact High-Power Blue Light from a Diode-Pumped Intracavity-Doubled Nd:YAG Laser

We report an efficient continuous wave (cw) operation of 946 nm and 473 nm laser beams generated from a diode-pumped composite Nd:YAG rod. A very simple compact linear cavity was employed with cavity length of 35 mm. A composite Nd:YAG laser rod was used to release thermal effects. The maximum cw output of 3.3 W at 946 nm was obtained with slope efficiency of 22% at incident pump power of 17.5 W. By intracavity doubling with an LBO crystal, as much as 590 mW of single-ended blue output at 473 nm was achieved with an optical-optical conversion efficiency of 3.4%. The total blue output would be 1.06 W with overall conversion efficiency of 6.1% if the lasers emitted in both the directions were taken into account.

Diode-Pumped Quasi-Three-Level Passively Q-Switched Nd:GGG Laser with a Codoped Nd,Cr:YAG Saturable Absorber

We demonstrate the first quasi-three-level passively Q-switched Nd:GGG laser at 937 nm using a Nd,Cr:YAG crystal as the saturable absorber. The dependences of the average output power, the repetition rate and the pulse width on the incident pump power are obtained. A maximum average output power of 1.18 W with repetition rate of 35 kHz and pulse width of 45 ns is achieved at an incident pump power of 18.3 W. The corresponding optical-to-optical and slope efficiencies are 6% and 10%, respectively.