Wenxiong Lin

Above 100 nJ all-normal-dispersion femtosecond pulse generation from a large-core multi-mode fiber laser

We demonstrate an all-normal-dispersion mode-locked fiber laser based on a piece of large-core Yb-doped multi-mode fiber. High order modes are suppressed by coiling the gain fiber to produce large loss for the high modes but low loss for the fundamental mode. Mode-locking is self-starting by exploiting a combination of a grating-aperture based spectral filter with a nonlinear polarization evolution effect. The laser directly delivers 1.1 ps, 107 nJ pulses at a repetition rate of 76.7 MHz, with an average power of up to 8.2 W. The pulses can be compressed externally to 210 fs with a peak power of up to 350 kW.

Efficient 2122 nm Ho:YAG laser intra-cavity pumped by a narrowband-diode-pumped Tm:YAG laser

We first demonstrate an efficient Ho:YAG laser intra-cavity pumped by a narrowband-diode-pumped Tm:YAG laser. The pump wavelength of the laser diode was selected according to the excitation peak which is also one of the absorption peaks of a 3.5 at. % Tm:YAG crystal and was locked by volume Bragg gratings. In the Tm laser experiment, a maximum output power of 11.12 W, corresponding to a slope efficiency of 51.6%, was obtained. In the Ho laser experiment, a maximum output power of 8.03 W at 2122 nm with a slope efficiency of 38% was obtained for 24.96 W of diode pump power incident on the Tm:YAG rod.

High-efficiency Tm-doped yttrium aluminum garnet laser pumped with a wavelength-locked laser diode

We first demonstrate a high-efficiency composite Tm-doped yttrium aluminum garnet laser end-pumped with a narrow-linewidth laser diode, which was locked at a wavelength of 784.9 nm with volume Bragg gratings. The locked pump wavelength was experimentally determined by the excitation peak, which was also the absorption peak of a 3.5 at.% Tm:YAG crystal around 785 nm, for the improvement of laser efficiency under high-intensity pumping. Under an absorbed pump power of 24.64 W, a maximum output power of 11.12 W at 2018 nm was obtained, corresponding to an optical to optical conversion efficiency of 45.1% and a slope efficiency of 52.4%.

High peak power first, second, and third order Stokes pulses based on intracavity self-stimulated Raman scattering lasers

We obtain high peak power pulses in megawatt range of the first (1181 nm), second (1321 nm), and third order (1500 nm) Stokes radiation from self-conversion of the 1067-nm laser radiation based on Nd:KGW laser. The maximum output energy of the first order Stokes laser is 35.3 mJ, which is to our knowledge, the highest reported energy in an intracavity Q-switched laser. The third order Stokes pulse is obtained in an intracavity Q-switched laser.

Design and performance of a composite Tm:YAG laser pumped by VBG-stabilized narrow-band laser diode

A 2-μm composite Tm:YAG laser pumped with a narrow-band laser diode was presented. The temperature distribution and thermal lens in the Tm:YAG were numerically simulated by a finite element method and the results were used to design the special cavity, in order to achieve a high efficiency and stable output. With a 25-W incident pump power, we obtained a maximum output power of 11 W at 2018.5 nm, corresponding to a slope efficiency of 51.3% and an optical-to-optical efficiency of 44.5%, respectively. The beam quality was measured to be and .

Generation of 3.8-GHz Picosecond Pulses From a Diode-Pumped Self-Mode-Locked Yb:YAG Thin Disk Laser

We report on a high-repetition-rate self-mode-locking laser with a diode-pumped Yb:YAG ceramic thin disk. The third nonlinearity of the gain medium is exploited to achieve stable CW mode-locking operation without using any additional components in the cavity. The laser produces 60-ps pulses at the central wavelength of 1032 nm with a repetition rate of 3.8 GHz and an average power of 780 mW.

Development of an injection-seeded single-frequency laser by using the phase modulated technique

An injection-seeded single-frequency Q-switched Nd:YAG laser is accomplished by using a phase modulated ramp-fire technique. A RbTiOPO4 (RTP) electro-optic crystal is selected for effective optical path length modulation of the slave self-filtering unstable resonator. This single-frequency laser is capable of producing 50 mJ pulse energy at 1 Hz repetition rate with a pulse width of 16 ns. The standard deviation of laser pulse intensity for consecutive 100 shots from the mean pulse intensity is less than 1.05%. A spectral linewidth of less than 0.5 pm with a frequency jitter of about 14 fm over 30 min is obtained.

High-repetition-rate single-frequency electro-optic Q-switched Nd:YAG laser with feedback controlled prelase

A stable high-repetition-rate, high pulse energy and single-frequency electro-optic Q-switched laser has been developed and demonstrated in this paper. The prelase technique has been used in this single-frequency laser. And a PID feedback control electronics is applied to stabilize the prelase. Meanwhile, a two-plate resonant reflector take the place of traditional dielectric output coupler mirror to enhance the single-axial-mode selection. And a Cr:YAG saturable absorber is also inserted in the cavity to improve single-axial-mode selection. Output laser power over 2 W with 10 ns pulse duration has been obtained at a repetition rate of 1 kHz. And the single-axial-mode probability was 100% in one hour without any manual adjustments. The experimental results show that the prelase technique is reliable to attain single-frequency operation.

An LD-pumped Q-switched Nd:YAG laser using La 3 Ga 5 SiO 14 for the electro-optic modulator and optical activity compensation

La3Ga5SiO14 (LGS) has been designed and used successfully not only as an electro-optical (EO) Q-switch but also as the optically active crystal in an Nd:YAG (yttrium aluminum garnet) pulse-off laser cavity with two-rod birefringence compensation in this paper. A maximum average output power of 15.8 W with a pulse width of 21 ns was obtained at the maximum repetition rate of 1 kHz, and the dynamic–static ratio was 75%. Experimental results revealed that the spatial distribution of the laser intensity with the two LGS crystals inserted between two identical Nd:YAG rods was significantly better than the spatial distribution with no birefringence compensation or a KD P EO Q-switcher.