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Biomedical subjects

Xiaohan Liu

Publications and source records attributed to Xiaohan Liu.

7 recordsLinked to original sources
PubMed2006

Omnidirectional total reflection for liquid surface waves propagating over a bottom with one-dimensional periodic undulations.

We study theoretically the propagation of liquid surface waves over a bottom with one-dimensional (1D) periodic undulations. We find a general criterion for omnidirectional total reflection in such a system. Numerical simulations based on a transfer matrix method demonstrate unambiguously the existence of omnidirectional total reflection for liquid surface waves propagating over a bottom with 1D periodic undulations.

Journal Article↗
PubMed2005

Structural origin of the brown color of barbules in male peacock tail feathers.

We report detailed optical measurements and numerical simulations of brown barbules in male peacock tail feathers. Our results indicate that brown coloration is predominantly produced structurally by the two-dimensional (2D) photonic-crystal structure in the cortex layer of a barbule. The constructing strategies of brown coloration revealed by numerical simulations are indeed subtle, which are of great significance in the artificial constructions of mixed structural coloration. It is found that the structural configurations of the 2D photonic-crystal structure such as the lattice constant, the number of periods, and even the interdistance and missing holes between the two melanin layers nearest to the cortex surface, are important in the production of structural brown colors.

Animals↗
PubMed2005

Self-collimation in liquid surface waves propagating over a bottom with periodically drilled holes.

Liquid surface waves propagating over a bottom with periodically drilled holes are studied experimentally and theoretically. Point source waves are generated in the center of the array of the periodically drilled holes in order to observe the evolvements of these waves. We successfully observe the self-collimation phenomenon in liquid surface waves. Band structures and constant-frequency surfaces are calculated, which can give a satisfactory interpretation of the experimental observations.

Journal Article↗
PubMed2004

Superlensing effect in liquid surface waves.

We present experimental observations and numerical simulations of superlensing effect in liquid surface waves. We use rigid cylinders to create a two-dimensional periodic lattice, in which liquid surface waves propagate. Through the observation of a superlensing effect, we demonstrate the existence of negative refraction in surface waves. In addition, a complete band gap is found.

Journal Article↗
PubMed2003

Complete band gaps for liquid surface waves propagating over a periodically drilled bottom.

A plane-wave expansion approach is developed to solve the mild-slope equation for liquid surface waves propagating over a bottom with periodic structures. Band structures are calculated for the bottom periodically drilled with the square or triangular lattice of holes. Complete band gaps are found for both lattices. Parameters that influence the formation of band gaps are discussed.

Journal Article↗
PubMed2003

Coloration strategies in peacock feathers.

We report the mechanism of color production in peacock feathers. We find that the cortex in differently colored barbules, which contains a 2D photonic-crystal structure, is responsible for coloration. Simulations reveal that the photonic-crystal structure possesses a partial photonic bandgap along the direction normal to the cortex surface, for frequencies within which light is strongly reflected. Coloration strategies in peacock feathers are very ingenious and simple: controlling the lattice constant and the number of periods in the photonic-crystal structure. Varying the lattice constant produces diversified colors. The reduction of the number of periods brings additional colors, causing mixed coloration.

Animals↗