Zheng Li-He

Passively mode-locked 2-μm Tm:YAP laser with a double-wall carbon nanotube absorber

We report on a diode-pumped passively continuous wave (cw) mode-locked Tm:YAP laser with a double-wall carbon nanotube (DWCNT) absorber operating at a wavelength of 2023 nm for the first time, to the best our knowledge. The DWCNT absorber is fabricated on a hydrophilic quartz substrate by using the vertical evaporation technique. The output power is as high as 375 mW. A stable pulse train with a repetition rate of 72.26 MHz is generated with a highest single pulse energy of 5.2 μJ.

Generation of 54 Fs Laser Pulses from a Diode Pumped Kerr-Lens Mode-Locked Yb:LSO Laser *

A diode pumped Kerr-lens mode-locked femtosecond Yb:LSO laser is experimentally demonstrated for the first time. The 54 fs laser pulses at central wavelength of 1052 nm with a bandwidth of 22.5 nm are obtained at the repetition rate of 113 MHz. To the best of our knowledge, this is the shortest pulse duration ever produced from the Yb-doped orthosilicates lasers family.

Diode-Pumped Soliton and Non-Soliton Mode-Locked Yb:GYSO Lasers

Diode-pumped soliton and non-soliton mode-locked Yb:(Gd1−x Yx)2SiO5(x = 0.5) lasers are demonstrated. Pulses as short as 1.4 ps are generated for the soliton mode-locked operation, with a pair of SF10 prisms as the negative dispersion elements. The central wavelength is 1056 nm and the repetition rate is 48 MHz. For the non-soliton mode locking, the output power could achieve ~1.2 W, and the pulse width is about 20 ps. The critical pulse energy in the soliton-mode locked operation against the Q-switched mode locking is much lower than the critical pulse energy in the non-soliton mode-locked operation.

A 1.7-ps pulse mode-locked Yb3 +:Sc2SiO5 laser with a reflective graphene oxide saturable absorber*

By using a reflective graphene oxide as saturable absorber, a diode-pumped passively mode-locked Yb3+:Sc2SiO5 (Yb:SSO) laser has been demonstrated for the first time. Without extra negative dispersion compensation, the minimum pulse duration of 1.7 ps with a repetition rate of 94 MHz was obtained at the central wavelength of 1062.6 nm. The average output power amounts to 355mWunder the absorbed pump power of 15W. The maximum peak power of the mode-locking laser is up to 2.2 kW, and the single pulse energy is 3.8 nJ.

Spectroscopic properties of Er/Ce-codoped La3Ga5SiO14

The Er-single-doped and Er/Ce-codoped La3Ga5SiO14 polycrystalline powders are synthesized by the solid-phase synthesis method. The room-temperature luminescence spectra of the samples are investigated. The Near-infrared-region spectroscopic properties of Er3+ ions in the La3Ga5SiO14 systems are analysed with Judd-Ofelt theory and rate equations. The effective deactivating effect of Ce3+ ions on Er3+ ions is confirmed.

Growth and spectroscopic characteristics of Nd-doped PbWO4 crystal

Nd-doped PbWO4 crystals are grown by using the modified Bridgman method. The spectroscopic properties of the crystals are investigated. The changes of the absorption band at 350 nm are discussed for samples annealed at 740 °C and 1040 °C. The radiative lifetime of the 4F3/2 level is calculated by using the Judd-Ofelt theory according to the absorption spectrum of 0.5 at.% Nd-doped PbWO4 crystal. The spontaneous Raman scattering properties of the crystals are analysed.

Kerr-Lens Self-Mode-Locked Laser Characteristics of Yb:Lu2SiO5 Crystal

A diode-pumped Kerr-lens self-mode-locked laser is achieved by using Yb: Lu2SiO5(Yb:LSO) crystal without additional components. Under the incident pump power of 14.44 W, a self-mode-locked output power of 2.98 W is obtained in the five-mirror cavity, corresponding to an optical-optical efficiency of 20.6%. Pulses as short as 8.2 ps are realized at 1059 nm, with the corresponding pulse energy and peak power of 28.9 nJ and 3.5 kW, respectively. A pair of SF10 prisms are inserted into the laser cavity to compensate for the group velocity dispersion. The pulse width is compressed to 2.2 ps with an average output power of 1.25 W.

Comparison of Laser Performances of 5at.% Yb:Gd2xY2(1?x) SiO5 Crystals between Different Cutting Directions

We investigate the laser actions of 5at.% Yb:Gd2xY2(1-x)SiO5 (Yb:GYSO; x = 0.1) crystals with different cutting directions, parallel and vertical to the growth axis. Our results show that the cutting direction of the sample plays an astonished role in the laser operation. The sample cut vertically to the growth axis possesses the favourable lasing characteristics. Its output power reaches 3.13W at 1060nm with a slope efficiency of 44.68% when the absorbed pump power is 8.9 W. In contrast, the sample cut parallel reaches only 1.65 W at 1044 nm with a slope elLiciency of 33.76% with absorbed pump power of 7.99 W. The absorption and emission spectra of the two samples are examined and the merit factor M is calculated. Our analysis is in agreement well with the experimental results. The wavelength tuning range of the superior sample covers from 1013.68 nm to 1084.82 nm.