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1

Spectro-Temporal Evolution and Transient Resonator in Solid-State Cr 3+: LiSAF Laser Emissions

Van Hao N., Dinh Hoang N., Viet Tiep P., Dai Hung N.

Computational Methods in Science and Technology

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2010

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Vol. spec. iss. (2)

xx-xx

EN

The Cr3+: LiSAF crystal is widely used as a laser medium of a wide gain spectrum from 700 nm to 920 nm. Our numerical investigations demonstrate a spectro-temporal evolution in the broadband Cr3+: LiSAF laser emission from Fabry-Perot resonator and particularly, from a low – Q resonator. Furthermore, the resonator transient and the phenomenon of relaxation oscillations in the solidstate Cr3+: LiSAF laser have been studied. Interestingly, using a diode-pump pulse of 100 mi s at 670 nm, a stable generation of single nanosecond Cr3+: LiSAF laser pulse at 850 nm is obtainable by simple choices of resonator parameters such as photon-cavity time and pump level. A pulse compression factor of 1 000 is achievable. As a result, a simple technique of short laser pulse generation at a high repetition rate of diode pumping pulses has been proposed.

2

Resonator Transients of all Solid-State Cr: LiSAF and Nd:YVO4 Lasers-Generation of Single Short Laser Pulse

Van Hao N., Trong Nghia N., Khoa Quang N., Dai Hung N.

Computational Methods in Science and Technology

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2010

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Vol. spec. iss. (2)

xx-xx

EN

The resonator transients and, in particular, the phenomenon of relaxation oscillations of diode end-pumped solid-state Cr:LiSAF and Nd:YVO4 lasers have been investigated at 850 nm and 1064 nm, respectively. The obtained results allow to understand clearly the resonator transients and show a generation of single laser pulses from the Cr:LiSAF and Nd:YVO4 lasers at near-threshold pumping levels. By proper choices of solid-state laser resonator and pumping parameters, obtainable duration of single solid-state laser pulses is computationally studied to be in nanosecond range and much shorter than the diode laser pumping pulse (100 mi s). As a result, a technique of single short laser pulse generation at high repetition rate of diode pumping pulses has been experimentally demonstrated. In our Nd:YVO4 laser pumped by 100 mi s diode laser pulse, single laser pulses as short as 93 ns at 1064 nm and pulse repetition rate as high as 3 kHz has been produced. The superior limit (about 3 kHz) in repetition rate of single Nd:YVO4 laser pulse mainly resulted from the fluorescence lifetime of active ion Nd3+.

3

Generation of Picosecond Laser Pulses at 1064 nm from All Solid-State Passively Mode-Locked Lasers

Quoc Khanh D., Trong Nghia N., Long P., Dinh Huy T., Dai Hung N.

Computational Methods in Science and Technology

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2010

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Vol. spec. iss. (2)

xx-xx

EN

Using semiconductor saturable absorber mirror and diode end-pumping configurations, all solid-state passively mode-locked Nd3+:YVO4 lasers have been successfully developed. The lasers efficiently provide a stable train of ultra-short laser pulses of 12 ps at 1064 nm at the pulse repetition rate adjustable from 8.8 MHz to 100 MHz. The peak power of 1.3 kW and an average laser power of 940 mW were obtained at the pulse repetitive rate of 60 MHz, corresponding to a laser conversion efficiency of 43 per cent. In order to obtain lower pulse repetitive rate and, therefore, higher peak power, a long laser resonator (larger than 15 m) is proposed and successfully developed for diode end-pumped passively mode-locked laser operation using a simple multiple-pass cavity configuration. As a result, the peak laser power up to 5.1 kW was obtained at the pulse repetitive rate of 8.8 MHz. The experimental results of the picosecond laser amplification and the harmonic generations at 532 nm (2nd), 355 nm (3rd) and 266 nm (4th) are presented.

4

Characteristics of Diode End-Pumped Passively Q-Switched Solid-State Cr 3+:LiSAF Laser

Van Hao N., Dinh Hoang N., Khoa Quang N., Duy Thang D., Dai Hung N.

Computational Methods in Science and Technology

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2010

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Vol. spec. iss. (2)

27-31

EN

We numerically investigated the characteristics of diode-end-pumped passively Q-switched solid-state Cr3+:LiSAF lasers. A Cr4+:YSO crystal is used as an intra-cavity saturable absorber. Our obtained results indicate the influences of resonator and pumping parameters on the characteristics of passively Q-switched solid-state Cr3+:LiSAF laser. Particularly, our numerical investigations are done in respect to the Cr3+:LiSAF laser medium of a very wide gain spectrum from 700 nm to 920 nm. Using a CW diode pumping at 670 nm and a Cr3+:LiSAF crystal of 3 mm long and 1 at.per cent, a stable generation of Q-switching nanosecond Cr3+:LiSAF laser pulse at 850 nm is obtainable with a pulse energy of about 2 mili-joule.