arXiv subjects

Peifeng Chen

Publications and source records attributed to Peifeng Chen.

3 recordsLinked to original sources

arXiv2020

Angular momentum conservation in counter-propagating vectorially structured light

It is well-known that electric spin angular momentum and electric orbital angular momentum are conserved under paraxial propagation of travelling waves in free-space. Here we study the electric and magnetic angular momentum in counter-propagating waves and show both theoretically and experimentally that neither component alone is conserved except in special cases. We attribute this non-conservation to spin-spin and orbit-orbit coupling between the electric and magnetic fields. This work generalises previous findings based on travelling waves, explains the apparent spin-orbit coupling in counter-propagating paraxial light, and broadens our understanding of angular momentum conservation in arbitrary structured light waves.

physics.optics↗

arXiv2019

Optical needles with arbitrary homogeneous three-dimensional polarization

We propose a new method to generate optical needles by focusing vector beams comprised of radially polarized component and azimuthally polarized vortex components. The radial part can generate longitudinal polarization, while the azimuthal parts can generate left- and right-handed polarization. Hence, an arbitrary 3D polarization can be obtained. To our knoeledge, it may be the first time that arbitrarily polarized optical needles whose transverse sizes are under 0.5$λ$ have been achieved. And their polarized homogeneity is beyond 0.97.

physics.optics↗

arXiv2006

All-electrical measurement of spin injection in a magnetic $p$-$n$ junction diode

Magnetic $p$-$n$ junction diodes are fabricated to investigate spin-polarized electron transport. The injection of spin-polarized electrons in a semiconductor is achieved by driving a current from a ferromagnetic injector (Fe), into a bulk semiconductor ($n$-GaAs) via schottky contact. For detection, a diluted magnetic semiconductor ($p$-GaMnAs) layer is used. Clear magnetoresistance was observed only when a high forward bias was applied across the $p$-$n$ junction.

cond-mat.mes-hall↗