We experimentally demonstrated a passively mode-locked femtosecond laser by using a graphene-based saturable absorber mirror (graphene SAM) in the spectral region of 2 μm. The graphene SAM was fabricated by transferring chemical-vapor-deposited, high-quality, and large-area graphene on a highly reflective plane mirror. Stable mode-locked laser pulses as short as 729 fs were obtained with a repetition rate of 98.7 MHz and an average output power of 60.2 mW at 2018 nm.

We have experimentally demonstrated a dual-wavelength synchronously mode-locked Nd:CNGG laser based on the semiconductor saturable absorber mirror technique. Mode locking was achieved simultaneously on two gain bands of the crystal that have a central wavelength separation of 2.4 nm. The fundamental mode-locked pulse train has a repetition rate of 88 MHz and pulse duration of 5 ps, with an average output power of approximately 90 mW. Autocorrelation measurements show that each of the synchronously mode-locked pulses consists of a train of quasi-periodic beat pulses with a 660 fs pulse width and a 0.63 THz repetition rate.

With MoS 2 as saturable absorber, passive Q-switching and Q-switched mode-locking operations of a Tm-doped calcium lithium niobium gallium garnet (Tm:CLNGG) laser were experimentally demonstrated. The Q-switched laser emitted a maximum average output power of 62 mW and highest pulse energy of 0.72 μJ. Q-switched mode locking was also obtained in the experiment. The research results will open up applications of MoS 2 at the mid-infrared wavelength.

Large Ca0.28Ba0.72Nb2O6 (CBN-28) single crystals exhibit saturated ferroelectric hysteresis loops under an electric field of 115kV∕cm along the [001] direction. Their spontaneous polarization, remanent polarization and coercive field are 35.3μC∕cm2, 32.2μC∕cm2, and 38.1kV∕cm, respectively. The dielectric constant and dielectric loss tanδ of the crystals are 195 and 0.32 at 10 kHz, respectively. A diffused dielectric anomaly with relaxor characteristic was observed in the range of 325-500 °C at low frequencies, while the CBN-28 crystals experienced a first-order normal-relaxor ferroelectric phase transition around 252 °C on heating. A broad dielectric loss peak appears around 120 °C and it is interpreted in terms of the migration of oxygen vacancies. The conductance activation energy was determined to be 1.33 eV in the high temperature regime (500–560 °C).

Barium tungstate (BaWO4) is employed to achieve efficient stimulated Raman scattering conversion in a compact diode-pumped actively Q-switched Nd:YAG laser. With an incident pump power of 9.2 W, 1.56 W of 1181 nm first-Stokes average output power was generated at a pulse repetition rate of 20 kHz, corresponding to an optical-to-optical conversion efficiency of 16.9%.