Pulses as short as 8.1 fs were generated from a blue laser-diode-pumped Kerr-lens mode-locked Ti:sapphire oscillator, with an average power of 27 mW and a repetition rate of 120.6 MHz. The full width at half-maximum exceeds 146 nm, benefitting from the dispersion management by a combination of a low-dispersion fused silica prism pair and a series of double-chirped mirrors. To the best of our knowledge, this is the first time to generate sub-10-fs pulses from a laser diode directly pumped Ti:sapphire oscillator.

We demonstrate a harmonically pumped femtosecond optical parametric oscillator (OPO) laser using a frequency-doubled mode-locked Yb:KGW laser at a repetition rate of 75.5 MHz as the pump laser. Based on a bismuth borate nonlinear crystal, repetition rates up to 1.13 GHz are realized, which is 15 times that of the pump laser. The signal wavelength is tunable from 700 nm to 887 nm. The maximum power of the signal is 207 mW at the central wavelength of 750 nm and the shortest pulse duration is 117 fs at 780 nm. The beam quality (M² factor) in the horizontal and vertical directions of the output beam are 1.077 and 1.141, respectively.

Transition metal dichalcogenides (TMDs) are successfully applied in fiber lasers for their photoelectric properties. However, in previous work, how to improve the modulation depth of TMD-based saturable absorbers (SAs) has been a challenging issue. In this paper, WSe2 and MoSe2 SAs are fabricated with the chemical vapor deposition method. Compared with previous experiments, the modulation depths of WSe2 and MoSe2 SAs with sandwiched structures are effectively increased to 31.25% and 25.69%, respectively. The all-fiber passively Q-switched erbium doped fiber lasers based on WSe2 and MoSe2 SAs are demonstrated. The signal-to-noise ratios of those lasers are measured to be 72 and 57 dB, respectively. Results indicate that the proposed WSe2 and MoSe2 SAs are efficient photonic devices to realize stable fiber lasers.

Materials in the transition metal dichalcogenide family, including WS2, MoS2, WSe2, and MoSe2, etc., have captured a substantial amount of attention due to their remarkable nonlinearities and optoelectronic properties. Compared with WS2 and MoS2, the monolayered MoTe2 owns a smaller direct bandgap of 1.1 eV. It is beneficial for the applications in broadband absorption. In this letter, using the magnetron sputtering technique, MoTe2 is deposited on the surface of the tapered fiber to be assembled into the saturable absorber. We first implement the MoTe2-based Q-switched fiber laser operating at the wavelength of 1559 nm. The minimum pulse duration and signal-to-noise ratio are 677 ns and 63 dB, respectively. Moreover, the output power of 25 mW is impressive compared with previous work. We believe that MoTe2 is a promising 2D material for ultrafast photonic devices in the high-power Q-switched fiber lasers.

Two-dimensional (2D) materials with potential applications in photonic and optoelectronic devices have attracted increasing attention due to their unique structures and captivating properties. However, generation of stable high-energy ultrashort pulses requires further boosting of these materials’ optical properties, such as higher damage threshold and larger modulation depth. Here we investigate a new type of heterostructure material with uniformity by employing the magnetron sputtering technique. Heterostructure materials are synthesized with van der Waals heterostructures consisting of MoS2 and Sb2Te3. The bandgap, carrier mobility, and carrier concentration of the MoS2-Sb2Te3-MoS2 heterostructure materials are calculated theoretically. By using these materials as saturable absorbers (SAs), applications in fiber lasers with Q-switching and mode-locking states are demonstrated experimentally. The modulation depth and damage threshold of SAs are measured to be 64.17% and 14.13J/cm2, respectively. Both theoretical and experimental results indicate that MoS2-Sb2Te3-MoS2 heterostructure materials have large modulation depth, and can resist high power during the generation of ultrashort pulses. The MoS2-Sb2Te3-MoS2 heterostructure materials have the advantages of low cost, high reliability, and suitability for mass production, and provide a promising solution for the development of 2D-material-based devices with desirable electronic and optoelectronic properties.