Shaojie Men

A graphene passively Q-switched Nd:YAG ceramic laser at 1123 nm

A 1123?nm ceramic Nd:YAG laser passively Q-switched by graphene grown on SiC wafer was demonstrated. With a pump power of 8.1?W, an average output power of 332?mW was obtained, corresponding to an optical-to-optical conversion efficiency of 4.1% and a slope efficiency of 7.8%. The pulse width was 875.7 ns with a pulse repetition rate of 46.8?kHz.

Single-frequency CaWO 4 Raman amplifier at 1178 nm

Single-frequency crystalline Raman amplifications at 1178 nm were demonstrated. The seeding laser was generated from a single-frequency continuous wave fiber Raman amplifier. Three stages of Raman amplifications from CaWO4 single crystals were realized with a pulsed 1064 nm Nd:YAG laser as the pumping source. The final output pulse energy at 1178 nm was 26.7 mJ, and the pulse width was 2.9 ns, corresponding to a peak power of 5.2 MW. The overall Raman amplification ratio was up to 4.6×10(6). The linewidth was less than 500 MHz.

A diode pumped passively mode-locked Nd:CaGdAlO4laser

A diode pumped passively mode-locked Nd:CaGdAlO4 (Nd:CGA) laser was demonstrated. By using a semiconductor saturable-absorber mirror (SESAM) as the modulator, stable mode-locked pulses with a duration of 6.0 ps and a repetition rate of 88.3 MHz have been achieved at a central wavelength of 1078.6 nm. The maximum output power of 452 mW was obtained under a pump power of 10 W.

Four-wavelength laser based on intracavity BaWO 4 Raman conversions of a dual-wavelength Q-switched Nd:YLF laser

By using diode-end-pumped acousto-optically Q-switched intracavity Raman laser configurations, we demonstrate a four-wavelength laser emitting at 1047.0, 1053.0, 1159.4 and 1166.8 nm. Two Nd:YLiF₄ crystals are employed to generate 1047.0-nm and 1053.0-nm laser radiations. These two lasers are then frequency converted by a BaWO₄ Raman crystal to generate 1159.4-nm and 1166.8-nm first-Stokes waves. With pulse synchronization realized, we obtain the maximum output powers of 427, 418, 423 and 332 mW for 1047.0-nm, 1053.0-nm, 1159.4-nm and 1166.8-nm lasers, respectively. The total optical-to-optical conversion efficiency is 15.1%.

Single frequency MOPA based on Nd:YAG single crystal fiber and rods

We demonstrate a single frequency 1064 nm master oscillator power amplifier (MOPA) system operating in macro-micro pulse scheme. The repetition rate for the macro pulses was 300 Hz with pulse duration of 300 μs. Micro pulses operated at 25 kHz. The master laser was a single-longitudinal-mode electro-optically Q-switched Nd:YAG laser with an output power of 250 mW and pulse duration of 33 ns. Three stages of power amplifiers based on Nd:YAG single crystal fiber and rods were designed. The final output power reached 31.3 W with pulse duration of 30 ns and linewidth of less than 130 MHz. Micro pulse energy of 13.9 mJ was obtained with a peak power of up to 464 kW. The beam quality factors (M2) were measured to be 1.56 and 1.76 in horizontal and vertical directions, respectively.

High power broadband LiF:F 2 - color center laser

A high power LiF:F(2)(-) color center laser is demonstrated with broadband emission. The excitation source is a quasi-continuous wave diode side-pumped acousto-optically Q-switched Nd:YAG laser. Under an incident 1064-nm laser power of 25.4 W, the highest output power of up to 4.7 W is obtained with a macro pulse repetition rate of 400 Hz and a micro pulse repetition rate of 50 kHz. The broadband emission is centered at 1142 nm with a bandwidth of 13 nm.

Synchronized dual tunable wavelength Q-switched Nd:Glass laser

A flash-lamp pumped electro-optically Q-switched dual tunable wavelength Nd:Glass laser is demonstrated. An Nd:Glass rod was selected as the laser medium and a DKDP crystal was employed as the Q-switch. A cubic polarizer was placed in the cavity to divide the randomly polarized radiation into two orthogonally polarized beams. The two beams were tuned by two Littman-gratings and output independently. For Q-switched operation, the tuning range was 1050.1 - 1061.6 nm and 1050.5 - 1060.2 nm for the horizontal and vertical polarizations, respectively. When the horizontally polarized output was fixed at 1059.1 nm, the synchronized vertically polarized one can be tuned from 1051.5 to 1057.5 nm.

Single frequency MOPA based on Nd:YAG bulk and fiber single crystals

By employing Nd:YAG single crystal fiber and rods, single frequency 1064-nm master oscillator power amplifier is realized. Output power is 31.3 W with peak power of 464 kW and linewidth of less than 130 MHz.

Actively Q-switched Nd:YAG twisted-mode cavity laser with a RTP electro-optic modulator

A single-longitudinal-mode Nd:YAG laser was demonstrated using a twisted-mode cavity and an etalon. Stable laser pulses at 10 kHz were obtained with a RTP electro-optic modulator. Under an incident pump power of 8.1 W, the maximum output power of the single-longitudinal-mode laser was 1.07 W, and the linewidth was less than 0.1 GHz.

Single-frequency Nd:GGG/BaWO 4 Raman laser emitting at 1178.3 nm

An actively Q-switched Nd:GGG/BaWO<inf>4</inf> single-frequency Raman laser at 1178.3 nm is demonstrated. Under a pulse repetition rate of 20 kHz, the maximum pulse energy was 12 μJ and the linewidth was less than 4.34×10⁻³ cm⁻¹.