Shuguang Deng

Bi-nanorod/Si-nanodot hybrid structure: surface dewetting induced growth and its tunable surface plasmon resonance

Hybrid nanostructures composed of plasmonic metal and semiconductor are receiving increasing attentions, owing to their unique optical features that are induced by the co-existence of localized surface plasmon resonance (SPR) and semiconduction as well as the synergistic interactions between these two components. Other than the structures based on conventional noble metals, a cost-effective structure based on non-noble metal is studied in this work. Utilizing the surface dewetting in Bi-Si system, the Bi-nanorod/Si-nanodots hybrid structure (BSHS) is prepared by alternated sputtering of Bi and Si at low rate. The shift, split, and high order excitation of SPRs in BSHS are studied combining numerical and theoretical simulation. Calculations of the optical extinction performed as a function of the size of BSHS show a guideline to tune its spectra.

Coexistence and competition of surface diffusion and geometric shielding in the growth of 1D bismuth nanostructures and their ohmic contact

We study the physical-vapor-deposition of 1D bismuth nanostructures. Bi nanowire elongating along [012] and/or [110] direction as well as anisotropic Bi nano-columns are physical-vapor-deposited successfully. The coexistence and competition of surface diffusion and geometric shielding are critical to their formation as well as growth mode transition among them. Since physical-vapor-deposition is a vacuum process, we make use of it to fabricate the ohmic contact to prevent the damage to the bismuth nanostructures brought by the etching to their thick surface oxide layer.

A Method for Measuring the Pulsewidth at Different Spatial Positions of Ultrashort Laser Pulses

In this letter, we propose a method for measuring the pulsewidths at different spatial positions of ultrashort laser pulses. By measuring the pulsewidths varying with spatial positions of chirped and chirped-free femtosecond laser pulses, it is found that pulsewidths at edge positions are longer than that of central positions due to the effect of residual spatial chirp. Then, we measure the temporal evolutions of pulse at the strongest spatial modulation position after small-scale self-focusing and our results show that the pulsewidths become narrower with increasing spatial contrast due to spatiotemporal coupling effect. We find that the method is reliable and feasible.

Evolution of temporal soliton solution to the generalized nonlinear Schrödinger equation with variable coefficients and PT-symmetric potential

In this paper, the evolution of temporal soliton is investigated analytically when a laser pulse propagates in the inhomogeneous nonlinear medium with a Scarff II parity-time (PT)-symmetric potential. After a detailed analyzing the evolution of the intensity and pulse width (PW) of a temporal soliton, it is find that the chirped-free and chirped temporal soliton are stable when the dispersion coefficient is a periodic modulated function. When the dispersion coefficient are the constant and the exponential decreasing function, the chirped-free temporal soliton is stable, while the chirped temporal soliton is gradually compressed.