Visible lasers are a fascinating regime, and their significance is illustrated by the 2014 Noble prizes in physics and chemistry. With the development of blue laser diodes (LDs), the LD-pumped solid-state visible lasers become a burgeoning direction today. Constrained by the scarce visible optical modulators, the solid-state ultrafast visible lasers are rarely realized. Based on the bandgap structure and optoelectronic properties of atomic-layer MoS₂, it can be proposed that MoS₂ has the potential as a visible optical modulator. Here, by originally revealing layer-dependent nonlinear absorption of the atomic-layer MoS₂ in the visible range, broadband atomic-layer MoS₂ optical modulators for the visible ultrafast pulse generation are developed and selected based on the proposed design criteria for novel two-dimensional (2D) optical modulators. By applying the selected MoS₂ optical modulators in the solid-state praseodymium lasers, broadband mode-locked ultrafast lasers from 522 to 639 nm are originally realized. We believe that this Letter should promote the development of visible ultrafast photonics and further applications of 2D optoelectronic materials.

A phylogenetic tree was constructed by sequencing rbcL genes of 33 species representing 19 genera of Ranunculaceae, and three related species, Mahonia bealei, Mahonia fortunei and Nandina domestica. The results showed that the rbcL sequences of these Ranunculaceae range from 1,346 bp to 1,393 bp. The results based on the phylogenetic tree indicated that Caltha and Trollius should not be put in the same tribe, and a close relationship betweenAdonis and Trollius is supported by our research, while Aquilegia should be in Thalictroideae. In combination with the morphological and chemical evidence, the generic classification of Ranunculaceae should be revised into five subfamilies: Hydrastidoideae, Coptidoideae, Helleboroideae, Thalictroideae and Ranunculoideae. We demonstrate that the rbcL gene is of great value for investigating generic to subfamilial relationships in Ranunculaceae.

Efficient continuous-wave laser emission at 1856 nm from a Tm,Mg:LiNbO 3 crystal slab with high Tm 3+ doping concentration is reported. A maximum output power of 2.62 W is realized with a slope efficiency of 19.6% and the beam quality factor M 2 of 1.7 at room temperature. We believe that this is the first demonstration of watt-level laser operation in Tm,Mg:LiNbO 3 crystal and the output power is four orders of magnitude higher than that reported previously in Tm-doped LiNbO 3 crystal. Performance degradation due to the photorefractive effect under high intensity 1856 nm laser is not observed thanks to the co-doping of magnesium ions. Quantitative analysis about the long-term photorefractive effect is also provided. Multi-wavelength laser operation is realized by using different narrow-band output couplers. This demonstration opens up a viable pathway towards 2-μm integrated optic devices for achieving laser oscillation, electro-optic and nonlinear optical effects within just one sample simultaneously. Opt. 12(3), 555-563 (1973). 25. A. Ashkin, G. D. Boyd, J. M. Dziedzic, R. G. Smith, A. A. Ballman, J. J. Levinstein, and K. Nassau, "Opticallyinduced refractive index inhomogeneities in LiNbO 3 and LiTaO 3 ," Appl. Phys. Lett. 9(1), 72-74 (1966).

No abstract

In this letter, the outage probability of an L-branch Maximal Ratio Combining (MRC) diversity system is evaluated under non-identical correlated lognormal shadowed Rayleigh fading channels by extending the Moment Generation Function (MGF) method to approximate the output signal-to-noise ratio (SNR) by a new lognormal random variable, whose cumulative distribution function (cdf ) is obtained by numerically solving for its mean and standard deviation. This cdf is then utilized to obtain the outage probability at a specific threshold. Extensive Monte Carlo simulations verify that the proposed approach is an accurate and efficient method to evaluate the desired outage probability, which would greatly facilitate the design and analysis of such systems.