High-quality 2-μm Q-switched pulsed solid-state lasers using spin-coating-coreduction approach synthesized Bi_2Te_3 topological insulators

In this paper, the fabrication process and characterization of Bi_2Te_3 topological insulators(TIs) synthesized by the spin-coating-coreduction approach(SCCA) is reported. With this approach, high-uniformity nano-crystalline TI saturable absorbers(TISAs) with large-area uniformity and controllable thickness are prepared. By employing these prepared TIs with different thicknesses as SAs in 2-μm solid-state Q-switched lasers, thickness-dependent output powers and pulse durations of the laser pulses are obtained, and the result also exhibits stability and reliability. The shortest pulse duration is as short as 233 ns, and the corresponding clock amplitude jitter is around 2.1%, which is the shortest pulse duration in Tl SA-based Q-switched 2-μm lasers to the best of our knowledge.Moreover, in comparison with the TISA synthesized by the ultrasound-assisted liquid phase exfoliation(UALPE)method, the experimental results show that lasers with SCCA synthesized TISAs have higher output powers, shorter pulse durations, and higher pulse peak powers. Our work suggests that the SCCA synthesized TISAs could be used as potential SAs in pulsed lasers.

Dual-wavelength synchronously mode-locked Tm-doped bulk laser with terahertz frequency beating

A dual-wavelength synchronously mode-locked homogeneously broadened bulk laser operating at 1985.6 and1989 nm is presented for the first time, to the best of our knowledge, which delivers a maximum output power of 166 m W and a repetition rate of 85 MHz. The pulse duration was measured to be 16.8 ps by assuming a sech2 pulse shape. The recorded autocorrelation trace showed frequency beating signals with an interval of 3.8 ps and a full width at half-maximum duration of 2 ps, corresponding to an ultrahigh beating frequency of about0.26 THz, which agrees well with the frequency difference of the emitted two spectral peaks. The results indicated that such a kind of dual-wavelength mode-locked Tm:YAlO3 laser could be potentially used for generating terahertz radiations.

Subnanosecond KTiOPO4 optical parametric oscillator intracavity pumped by a Kerr-lens, mode-locked YVO4/Nd:YVO4 laser coupled with an acousto-optic modulator

A Kerr-lens, mode-locked YVO4∕Nd:YVO4laser coupled with an acousto-optic modulator（AOM） Q-switching near1064 nm was employed to pump an intracavity KTi OPO4（KTP） optical parametric oscillator. A subnanosecond signal wave near 1572 nm with low repetition rate was realized. At an AOM repetition rate of 8 kHz, the maximum output power was 165 mW. The highest average pulse energy, the shortest duration, and the highest peak power of a mode-locking signal pulse were estimated to be ～10.3 μJ, ～120 ps, and ～82 kW, respectively.

High peak power subnanosecond pulse characteristics with different wall structured CNTs in a doubly QML Nd:Lu_(0.15)Y_(0.85)VO_4 laser

By simultaneously employing both an electro-optic modulator and carbon nanotube saturable absorber(CNT-SA)in a dual-loss modulator, a subnanosecond single mode-locking pulse underneath a Q-switched envelope with high peak power was generated from a doubly Q-switched and mode-locked(QML) Nd:Lu_(0.15)Y_(0.85)VO_4 laser at1.06 μm for the first time, to our knowledge. CNTs with different wall structures—single-walled CNTs(SWCNTs),double-walled CNTs(DWCNTs), and multi-walled CNTs(MWCNTs)—were used as SAs in the experiment to investigate the single mode-locking pulse characteristics. At pump power of 10.72 W, the maximum peak power of1.312 MW was obtained with the DWCNT.

Mid-infrared Q-switch performance of ZrC

Zirconium carbide(ZrC)with layered structure and nanoparticle morphology was prepared by sonication in an ethyl alcohol solvent.The morphology and saturable absorption properties of the ZrC were systematically analyzed.By using ZrC nanoparticle coated substrates as saturable absorbers,stable Q-switched 3μm Er:Lu_(2)O_(3) lasers were realized.Pulse durations of 50 ns with pulse energies of 20μJ and peak power of 0.4 kW are the shortest obtained with novel-material-based Q-switched lasers in the 3μm wavelength range.