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In this article, a high-power diode-end-pumped passively Q-switched (PQS) Tm:YAP laser is reported with novel two-dimension (2D) molybdenum ditelluride (MoTe 2 ) as a saturable absorber (SA). By using the open-aperture Z-scan method, the saturable absorption properties around 2.0 μm was characterized with a saturable fluence of 2.26 μJ∕cm 2 and a modulation depth of 6.0% for the as-prepared MoTe 2 SA. The band structure of MoTe 2 with the introduction of Te vacancies is simulated by the DFT method, and the results indicate that the bandgap can be reduced with the vacancies in a suitable range. The shortest pulse width of 380 ns was obtained with an average output power of 1.21 W at a repetition rate of 144 kHz, corresponding to a maximum single pulse energy of 8.4 µJ and peak power of 22.2 W. It is the first presentation of MoTe 2 as the saturable absorber in 2.0 μm solid-state pulse laser generation and the pulse width is the shortest among 2.0 μm solid-state lasers passive Q-switched with transitional metal dichalcogenides (TMDs) SAs to the best of our knowledge. The results indicated that MoTe 2 should be an excellent optical modulator for high repetition rate and short pulsed laser generation in a broadband spectral range.

The high efficiency acousto-optic modulators become indispensable in photonics and optoelectronics for the pulse generation and signal modulation in optical display and telecommunications. In this paper, the validity and feasibility of the biaxial crystals as acousto-optic mediums have been theoretically analyzed and confirmed by experiments using a biaxial crystal of β-BaTeMo 2 O 9 . The diffraction angle and diffraction efficiency of the β-BaTeMo 2 O 9 acousto-optic Q-switch are determined to be 1.420° and 78.1%, which are comparable with that of TeO 2 acousto-optic modulator at the identical operating wavelength of 1064 nm and 100 MHz, respectively. The minimum of the modulated pulse width can be achieved to be 6 ns at 5 kHz with Nd:YVO 4 as the gain medium. The results not only provide an excellent acousto-optic medium, but also explore the field of biaxial acousto-optic medium for device fabrications.