The evolutions of the pulses propagating in decreasing and increasing gain distributed fiber amplifiers with finite gain bandwidths are investigated by simulations with the nonlinear SchrSdinger equation. The results show that the parabolic pulse propagations in both the decreasing and the increasing gain amplifiers are restricted by the finite gain bandwidth. For a given input pulse, by choosing a small initial gain coefficient and gain variation rate, the whole gain for the pulse amplification limited by the gain bandwidth may be higher, which is helpful for the enhancement of the output linearly chirped pulse energy. Compared to the decreasing gain distributed fiber amplifier, the increasing gain distributed amplifier may be more conducive to suppress the pulse spectral broadening and increase the critical amplifier length for achieving a larger output linearly chirped pulse energy.
Noble metal nanoparticles,such as gold or silver nanoparticles and nanorods,exhibit unique photonic,electronic and catalytic properties.Functionalization of noble metal nanoparticles with biomolecules(e.g.,protein and DNA) produces systems that possess numerous applications in catalysis,delivery,therapy,imaging,sensing,constructing nanostructures and controlling the structure of biomolecules.In this paper,the recent development of noble metal nanoparticle-biomolecule conjugates is reviewed from the following three aspects:(1) synthesis of noble metal nanoparticle-biomolecule systems by electrostatic adsorption,direct chemisorption of thiol derivatives,covalent binding through bifunctional linkers and specific affinity interactions;(2) the photonic properties and bioactivation of noble metal nanoparticle-biomolecule conjugates;and(3) the optical applications of such systems in biosensors,and medical imaging,diagnosis,and therapy.The conjugation of Au and Ag nanoparticles with biomolecules and the most recent optical applications of the resulting systems have been focused on.
