RESUMO
Results of a theoretical study of piezoresistance properties of Dirac structures on example graphene nanoribbons with different types of a conductivity, both ideal and doped with point substitution defects of various concentrations uniformly distributed in the crystal lattice, are presented. Boron and nitrogen atoms are chosen as acceptor and donor impurities respectively. Using the tight-binding method and the Anderson's model, the band structure of the nanoparticles under study is simulated. The longitudinal component of the elastic conductivity tensor is analytically calculated. Its dependence on the relative strain of longitudinal compression and tension, the concentration of impurities and the width of the nanoribbon are studied. The physical substantiation of the results obtained is given.
RESUMO
We demonstrate femtosecond operation of a Nd-doped mi-crostructure fiber laser. The fiber provides gain and anomalous dispersion at the lasing wavelength of 1.06 microm and enables the construction of short and simple cavity designs. The laser is passively mode-locked by the combined action of a saturable absorber mirror, fiber nonlinearity, and dispersion and produces transform limited sub-400-fs pulses with a pulse energy as high as 100 pJ.
