L. H. Zheng

Spectroscopic properties and CW laser operation of Nd, Y-codoped CaF2 single crystals

Spectroscopic properties of Nd:CaF2 crystals with different doping concentrations of Nd3+ and codoping concentrations of Y3+ were investigated. The effect of codoping with Y3+ ions on the absorption and emission spectra, emission lifetimes, quantum efficiency, and emission cross sections of Nd3+ were studied. In particular, codoping with Y3+ ions increases the width of the emission lines over that found with Nd-doped glasses, and allows true CW laser operation around 1.06 μm.

Diode-pumped continuous wave tunable and graphene Q-switched Tm:LSO lasers

We have investigated the lasing characteristics of Tm:LSO crystal in three operation regimes: continuous wave (CW), wavelength tunable and passive Q-switching based on graphene. In CW regime, a maximum output power of 0.65 W at 2054.9 nm with a slope efficiency of 21% was achieved. With a quartz plate, a broad wavelength tunable range of 145 nm was obtained, corresponding to a FWHM of 100 nm. By using a graphene saturable absorber mirror, the passively Q-switched Tm:LSO laser produced pulses with duration of 7.8 μs at 2030.8 nm under a repetition rate of 7.6 kHz, corresponding to pulse energy of 14.0 μJ.

Passively Q-switched Nd:Sc 0.2 Y 0.8 SiO 5 dual-wavelength laser with the orthogonally polarized output

We have demonstrated a laser-diode pumped continuous-wave (CW) and passively Q-switched laser with a Nd:Sc(0.2)Y(0.8)SiO(5) (Nd:SYSO) crystal for the first time. In the CW operation, the laser was found to oscillate in tri-wavelength regime at 1074.8 nm, 1076.6 nm and 1078.2 nm, respectively. The maximum CW output power of 1.96 W was obtained, giving an optical-to-optical conversion efficiency of 35% and a slope efficiency of 39%. Using either Cr(4+):YAG or V(3+):YAG crystal as saturable absorber, stable passively Q-switched laser was obtained at dual-wavelength of 1074.8 nm and 1078.2 nm with orthogonal-polarization. The maximum average output power, pulse repetition rate, and shortest pulse width were 1.03 W, 50 kHz, and 24 ns, respectively. The passively Q-switched dual-wavelength laser could be potentially used as a source for generation of terahertz radiation.

A tri-wavelength synchronous mode-locked Nd:SYSO laser with a semiconductor saturable absorber mirror

We report on the generation of passive mode locking of a Nd:Sc0.2Y 0.8SiO5 (Nd:SYSO) laser using a semiconductor saturable absorber mirror. Linear polarized, tri-wavelength synchronous mode-locked pulses were obtained for laser emissions at 1075.55, 1076.80 and 1078.20 nm. An interference pattern was observed in the autocorrelation trace, the beat pulse had a repetition rate of 0.345 THz and the beat pulse width was 646 fs. Numerical simulation was conducted to clarify the formation of the autocorrelation trace.

A diode-pumped passively Q-switched Tm,Ho:YAP laser with a single-walled carbon nanotube

In this letter we present diode-pumped continuous wave (CW) and passively Q-switched a-cut and b-cut Tm,Ho:YAP lasers with a single-walled carbon nanotube saturable absorber (SWCNT-SA). In the CW regime, a maximum output power of 1.61 W at 2118.3 nm corresponding to a slope efficiency of 33.7% and a maximum output power of 1.23 W with a slope efficiency of 28.7% at 2129.6 nm were achieved from the a- and b-cut Tm,Ho:YAP lasers, respectively. With a SWCNT employed as the saturable absorber, passively Q-switched a- and b-cut Tm,Ho:YAP lasers were both realized. The a-cut Tm,Ho:YAP laser generated a 245 ns pulse at 2128.3 nm with a repetition rate of 400 kHz, while the b-cut Tm,Ho:YAP laser produced a 135 ns pulse at 2130 nm with a repetition rate of 245 kHz.

Comparative investigations on continuous wave operation of a-cut and b-cut Tm,Ho:YAlO3 lasers at room temperature.

The Tm,Ho:YAlO3 laser performance for two crystal orientations pumped by a wavelength tunable Ti:Sapphire laser is presented in this paper. An experimental investigation comparing a- and b-oriented Tm,Ho:YAlO3 crystals laser performance is demonstrated and discussed. Single- and multi-wavelength operations of Tm,Ho:YAlO3 lasers have been investigated in detail. The maximum output powers of 890 mW at 2119 nm for a-oriented Tm,Ho:YAlO3 crystal and 946 mW at 2103 nm for b-oriented Tm,Ho:YAlO3 crystal have been obtained, respectively. The two crystals show very similar performance in terms of output power and conversion efficiency, only that the b-cut Tm,Ho:YAP crystal demonstrates more regimes of multi-wavelength operations.

Diode-pumped passively mode-locked Yb:LSO/SESAM laser

Diode-end-pumped passively mode-locked Yb3+:Lu2SiO5 (Yb:LSO) lasers both in the picosecond and the femtosecond regimes were demonstrated in this paper. The mode-locked lasers were initiated by using of semiconductor saturable absorber mirrors (SESAM). In the absence of intra-prisms for pulse compression, the laser emitted 1.6 W of output power with pulses width of about 4.3 ps. A pair of SF10 prisms was inserted into the laser cavity, pulses as short as 699 fs was generated around a center wavelength of 1043.6 nm with an average output power of 800 mW and a peak power of 11.0 kW.

Mode-locked Tm,Ho:YAP laser around 2.1 μm.

A passively mode-locked Tm,Ho:YAP laser around 2.1 μm wavelength employing a semiconductor saturable absorber mirror is demonstrated. Stable continuous wave mode-locking operation was achieved at variable center wavelengths of 2036.5 nm, 2064.5 nm, 2095.5 nm, 2103.5 nm, and 2130 nm, respectively. Pulses as short as 40.4 ps were obtained at 2064.5 nm with a spectral FWHM of 0.5 nm at output powers of 132 mW and a repetition rate around 107 MHz. A maximum output power of 238 mW was obtained at 2130 nm with a pulse duration of 66 ps.

Characteristics of a diode-pumped Yb:CaF2-SrF2 mode-locked laser using a carbon nanotube absorber

Yb:CaF2–SrF2 disordered crystals are successfully grown by the TGT method. By using a double-walled carbon nanotube saturable absorber (DWCNT-SA), the continuous-wave mode-locked (CWML) laser properties of Yb:CaF2–SrF2 crystals are demonstrated under diode pumping for the first time. The mode-locked laser delivers pulses as short as 5 ps at a center wavelength of 1045.5 nm without any dispersion compensation. The oscillator operating at a repetition rate of ~87 MHz delivers 292 mW average output power.

Passive picosecond and femtosecond mode-locking laser action of Yb3+:LuYSiO5

Efficient passive mode locking of a diode-pumped Yb3+:LuYSiO5 (Yb:LYSO) laser is first demonstrated in experiment using a semiconductor saturable absorber mirror (SESAM), to the best of our knowledge. A stable pulse train with a repetition rate of 101 MHz is generated. The average output power of 2.13 W and the pulse duration of 3.9 ps. With a pair of SF10 uncoated prisms for dispersion compensation, we obtained pulses as short as 780 fs with center wavelength around 1042 nm, the average output power of 1.03 W and the peak power of 13.1 kW.