Jin Guangyong

A 200 kHz Q-Switched Adhesive-Free Bond Composite Nd:YVO4 Laser using a Double-Crystal RTP Electro-optic Modulator

A diode-end-pumped electro-optic (EO) Q-switched adhesive-free bond composite Nd:YVO4 laser operating at a repetition rate of 200 kHz is reported. A pair of RbTiOPO4 (RTP) crystals are used as a high repetition EO Q-switch. At the repetition rate of 200 kHz, the maximum average output power of 11.8 W at wavelength 1064 nm and full width at half maximum of pulses of 16.65 ns are achieved at an incident pump power of 27 W, corresponding to an optical conversion efficiency of 43.7% and a slope efficiency of 44.6%, respectively. To the best of our knowledge, this is the highest repetition rate reported on the EO Q-switched laser by using RTP crystals.

High coupling efficiency and low signal light loss (2 + 1) × 1 coupler *

The coupling efficiency of the pump coupler determines the pump light injection capacity of a laser system. Experimental analysis of the influences of different factors on the pump coupling efficiency is in accordance with this conclusion. We use two Nufern fibers (400 μm/440 μm with NA = 0.22) as pump arm, one Nufern fiber (20 μm/400 μm with NA = 0.06/0.46) as a main fiber to make a side-pumping (2+1)× 1 coupler. The experimental result shows that the total output power of this (2+1)× 1 coupler is about 1160 W, corresponding to a coupling efficiency as high as 98.6%. The loss of signal light is less than 1%.

An Innovative Electro-Optic Q-Switch Technology in 1064 nm and 1319 nm Dual-Wavelength Operation of a Nd:YAG Laser

An innovative electro-optic (EO) Q-switch technology in 1064nm and 1319nm dual-wavelength operation of a Nd:YAG laser is illustrated. Output energy of 4.6mJ and pulse width of 400ns for 1064nm and output energy of 8.7mJ and pulse width of 80 ns for 1319 nm are achieved simultaneously at the repetition rate of 1 Hz and pumping voltage of 750 V by using this bias voltage electro-optic Q-switched-technology when the voltage on LiNbO3 crystal is 2254 V. The strong line of 1064 nm in Q-switched operation is inhibited efficiently.

Thermal analysis of double-end-pumped Tm:YLF laser

Based on the steady heat conduction equation, LD double-end-pumped anisotropic Tm:YLF crystal temperature field analytical expression and thermal focal length are obtained by the integral-transform method. The influence of pump conditions and crystal parameters on the distribution of temperature and thermal focal length are quantitatively analyzed. The simulation results showed that increasing the pump power, decreasing waist radius, increasing doping concentration or decreasing crystal length, the temperature rise of crystal and nonuniformity of the thermal distortion are intensified, the corresponding thermal effects enhance, the thermal focal length gets shorter. The anisotropic of the physical and optical parameter of Tm:YLF crystal leads to the anisotropic of thermal effect. When the product of crystal length and doping concentration is a constant value, the thermal focal length keeps a basic consistent.

An intra-cavity pumped dual-wavelength laser operating at 946 nm and 1064 nm with Nd:YAG + Nd:YVO4 crystals

We adopt a compact intra-cavity pumped structure of Nd:YAG and Nd:YVO4 crystals to develop an efficient dual-wavelength laser that operates at 946 nm and 1064 nm. A 808 nm laser diode is used to pump the Nd:YAG crystal, which emits at 946 nm, and the Nd:YVO4 crystal, which emits at 1064 nm, is intra-cavity pumped at 946 nm. In order to avoid unnecessary pump light passing though the Nd:YAG crystal, reaching the Nd:YVO4 crystal and having an impact on the cavity pump, the two crystals are placed as far from one another as possible in this experiment. The output power at 1064 nm can be adjusted from 1 W–2.9 W by varying the separation between the two crystals. A total output power of 4 W at the dual-wavelengths is achieved at an incident pump power of 30.5 W, where the individual output powers for the 946 nm and 1064 nm emissions are 1.1 W and 2.9 W, respectively.

A Narrow Linewidth Continuous Wave Ho:YAG Laser Pumped by a Tm:YLF Laser*

A narrow linewidth cw Ho:YAG laser pumped by a 1908nm Tm:YLF laser based on the volume Bragg grating is established. The maximum output power of 9.6 W for the incident pump power of 16.9 W is obtained, and the corresponding slope efficiency and optical-to-optical conversion efficiency are 67.2% and 56.8%, respectively. The Ho:YAG laser operates stably at 2122.1 nm by using two Fabry-Perot etalons, with a full width at half maximum less than 0.2 nm.

High conversion efficiency, high power density Q-switched fiber laser

An acoustic—optic Q-switched all-fiber laser with a high-repetition-rate, a short pulse width, a wide spectrum, and a high conversion efficiency is experimentally demonstrated. In the laser configuration, a (1+1) × 1 side-pumping coupler is introduced to perform backward pumping, and a 10/130-μm Yb fiber is adopted. The acoustic—optic component operates in the first direction, achieving a Q-switched pulse with a repetition rate adjustable in the range of 20 kHz–80 kHz. Under a repetition rate of 20 kHz and a pump power of 6.76 W, the fiber laser obtains a highly efficient and stable pulse output, with an average power of 4.3 W, a pulse width of 56 ns, a peak power of 3.83 kW, and a power density of 1.39 × 1010 W/cm2. Particularly, the optic—optic conversion efficiency of the laser reaches as high as 64%. Another feature of the pulsed laser is that the high reflection mirror reflects the pump light as well, which brings the secondary absorption of the pump power into the gain fiber.

Double-Arched LD Array Stagger Pumped Electro-Optic Q-Switched Nd:YAG Laser without Water Cooling

We report an experimental study on a double-arched LD array stagger pumped electro-optic Q-switched Nd:YAG laser without water cooling by using a convex-concave compensate resonator. Perfect matching of the gain field inside the rod and the fundamental mode of the cavity is made by this structure. When the repetition rate is 20 Hz, A maximum output energy at 1064 nm wavelength of 176 mJ (M2 = 1.55) and 9.6 ns FWHM pulse width in fundamental mode Q-switch operation is obtained with LD injection current 120 A. The optical-optical conversion efficiency is 14.7%, the divergence angle of the output beam is about 1.8 mrad.