Initial Transmission Of Cr4 Research Articles

Passive Q-switch laser operation of circular, buried depressed-cladding waveguides realized by direct fs-laser beam writing in Nd:YAG/Cr^4+:YAG composite media

Circular, buried depressed-cladding waveguides were inscribed by direct fs-laser beam writing in diffusion-bonded Nd:YAG/Cr4+:YAG composite media. Passive Q-switch operation was achieved using the pump at 807 nm with a fiber-coupled diode laser. Laser pulses at 1.06 μm with energy of 15.7 μJ and 3.9-ns duration (corresponding to a peak power of 4.0 kW) were obtained from a waveguide of 150-μm diameter that was realized in a 10.3-mm long, 1.0-at.% Nd:YAG/Cr4+:YAG composite medium. The length of Nd:YAG crystal was 7.0 mm and initial transmission of Cr4+:YAG saturable absorber crystal was 0.70. The average output power reached 1.13 W.

57 mJ with 10 ns passively Q-switched diode pumped Nd:YAG laser using Cr4+:YAG crystal

In this paper, a side diode pumped passively Q-switched Nd:YAG laser is presented using a Cr4+:YAG as saturable absorber. The performance of the Nd:YAG laser in the free-running and Q-switched modes is theoretically and experimentally studied with different output coupler reflectivities and different initial transmissions of Cr4+:YAG crystals. The optimum reflectivity of the output coupler is found to be 25 % in the Q-switched mode according to the theoretical calculations and experimental results. The initial transmission of Cr4+:YAG is set to 20 % in order to achieve maximum output energy in a single laser pulse. The experimental results are in good agreement with calculated values. In the Q-switched mode, single pulse output energy is obtained around 57 mJ with 10 ns pulse duration over 1–20 Hz pulse repetition rates. The optical to optical conversion efficiency reaches 14.25 %.

Numerical simulation of subnanosecond single mode-locking pulse generation in a doubly Q-switched and mode-locked green laser with EO and Cr^4+:YAG

Under the Gaussian spatial distribution approximation, the coupled rate equations for a diode-pumped, dual-loss-modulated, Q-switched, and mode-locked (QML) green laser with EO and Cr4+:YAG are derived. The numerical simulation results show that the pulse width of the Q-switched envelope is related to the pump power, repetition rate of EO, initial transmission of Cr4+:YAG, and the stimulated emission section of the gain medium. By designing the related parameters well, the pulse width of the Q-switched envelope can be greatly compressed to shorter than the cavity roundtrip transmit time, i.e., the interval of two neighboring mode-locking pulses; then subnanosecond single mode-locking pulses with low repetition rate, high pulse energy, and high stability can be obtained. The generation conditions of subnanosecond single mode-locking pulses per envelope in a dual-loss-modulated QML Nd:Lu0.15Y0.85VO4 green laser with EO and Cr4+:YAG are experimentally demonstrated and found to be in agreement with the theoretical results.

Near-diffraction-limited passively Q-switched Yb:Y3Al5O12 ceramic lasers with peak power >150kW

Laser-diode pumped nearly diffraction-limited beam quality (M2<1.05), high peak power, subnanosecond passively Q-switched Yb:Y3Al5O12 ceramic miniature laser with Cr4+:Y3Al5O12 ceramic as saturable absorber has been achieved. The slope efficiency is as high as 36% for 80% initial transmission of Cr4+:Y3Al5O12 ceramic. The pulse width of 335ps and peak power of over 150kW at repetition rate of 5kHz were obtained. Laser oscillates at single-longitudinal-mode oscillation and wide-separated multilongitudinal-mode oscillation due to the combined etalon effect of the Cr4+:YAG thin plate and thin glass plate as output coupler.