Ling Wei-Jun

Diode-Pumped Self-Starting Mode-Locked Nd:YVO4 Laser with Semiconductor Saturable Absorber Output Coupler

By using a semiconductor saturable-absorber output coupler as a mode-locking device, we experimentally realized the operation of a diode-pumped passively mode-locked Nd:YVO4 laser. Stable laser pulses with duration of 2.3 ps were generated at the output power of about 1 W. With increasing the pump power to 9 W, the maximum mode-locked power of 1.7 W was obtained, which corresponds to a slope conversion efficiency of 44% and optical-to-optical conversion efficiency of 19%.

Acoustic Diagnostics of Plasma Channels Induced by Intense Femtosecond Laser Pulses in Air

Long plasma channels induced by femtosecond laser pulses in air are diagnosed using the sonographic method. By detecting the sound signals along the channels, the length and the electron density of the channels are measured. Refocusing is also observed at different laser energies and different focal lengths. We find that the sonographic method has manifest advantages compared to other techniques.

Self-starting passively mode-locking all-solid-state laser with GaAs absorber grown at low temperature

We realize a stable self-starting passively mode-locking all-solid-state laser by using novel GaAs mirrors as the absorber and output coupler. The GaAs mirror is grown by the technology of metal organic chemical vapour deposition at low temperature. With such an absorber as the output coupler in the laser resonator, laser pulses with duration of 42ps were generated at a repetition rate of 400MHz, corresponding to the average power of 590mW.

Multi-wavelength ultraviolet terawatt-order CPA system

We set up a multi-wavelength ultraviolet terawatt-order chirped pulse amplification (CPA) system according to the CPA technology and the frequency conversion technology. The system offers 1Hz, 5Hz and 10Hz high energy ultraviolet pulses by precise time synchronization among 5 repeat frequencies. The RMS of output energy fluctuation rate of CPA is less than 2% with using a pre-amplified system of energy fluctuation rate less than 0.3% RMS and a time synchronizer with time jitter less than 3 ns. The multi-wavelength high energy ultraviolet pulses with 64 mJ/400 nm,16 mJ/267 nm and 5 mJ/205 nm are obtained, and their corresponding peak powers reach the terawatt level.

High Power Continuous-Wave Actively Mode-Locked Diode-Pumped Nd:YAG Laser

We demonstrate a diode-pumped cw mode-locked Nd:YAG by an acousto-optic mode locker. A mode-locked pulse with duration of 345 ps and output power of 12 W is obtained. The resonator design shows three advantages: a larger mode volume, high stability against thermal lens fluctuations, and excellent beam quality with TE00 mode. Different from previous active mode locking designs, we employ a frequency stabilizer and a phase-lock loop circuit to ensure the mode locking stable operation.

Compact single-stage femtosecond multipass Ti : sapphire amplifier at 1kHz with high beam quality

A compact femtosecond Ti:sapphire amplifier system is reported using single-stage multipass configuration with high beam quality. A high dispersion glass stretcher and a pair of double prisms for compression are introduced based on broadband femtosecond seed pulses. The non-grating-based pulse stretcher and compressor are advantageous to increase high beam quality and to reduce the high-order dispersion. A Gaussian filter is used to reduce the gain narrowing effect in amplification. The compact femtosecond Ti:sapphire nine-pass amplifier delvers pulses with a duration of 26 fs and an energy of 800 mu J at 7 mJ pumping pulses energy at 1 kHz. The 1-kHz femtosecond amplifier with a high beam quality and high stability is very suitable for ultrafast physics research applications, such as attosecond science, ultra-precision micromatching, and THz wave generation.

Self-starting mode-locked picosecond Ti : sapphire laser by using of a fast SESAM

A stable continuous wave mode-locked picosecond Ti:sapphire laser by using a fast semiconductor saturable absorber mirror (SESAM) is demonstrated. The laser delivers pulse width of 20 ps at a central wavelength of 813 nm and a repetition rate of 100 MHz. The maximum output power is 1.34 W with pump power of 7 W which corresponds to an optical–optical conversion efficiency of 19.1%.