We present an optically controlled terahertz (THz) switch to tune the state of polarization based on single-layer chiral metamaterial. The chiral metamaterial consists of an array of perforated S-shaped slits with incorporated photoactive silicon, which allows us to control dynamically cross-polarization transmission. The switch state can be efficiently controlled by external optical stimuli. The realization of cross-polarization THz switch in a single-layer metamaterial has simple structure design and easy fabrication and therefore the S-shaped metamaterial will be a promising candidate for polarization control devices.
Gold nanoparticles are widely employed in nanomaterials, nanobiotechnology and health care, but generally they are
considered difficult to trap stably. Compared with the continuous laser which is popular to the optical trapping, pulse
laser has a relatively larger power in its work pulse, which is useful for trap particles. So this paper comprehensively
analyzes the forces (the radiation forces, the gravitation, and the Brownian motion) on the gold nanoparticles in the
optical tweezers formed by a pulse laser, through building up a mathematical model. Finally gets the dependence relation
between the characteristics of the pulse laser and that of the gold nanoparticles.
Gold nanoparticles have found broad applications in nanomaterials and nanobiotechnology and health care. They are
considered to be superior handles or probes relative to polystyrene beads for their own specific physical characteristics.
But unfortunately they are considered difficult to trap stably by optical tweezers still owing to their specific physical
characteristics. In this paper, numerical studies are carried out to show that how the radiation forces on the gold particles
dependant on the parameters of the lasers and of the particles. The results show that a stable trap for gold particles needs
a more strictly choice of lasers than polystyrene nanobeads for given particle size and other conditions.
The effects of the linear birefringence inside a bulk glass current sensing element and the incident polarizing angle upon the performance of a bulk glass optical current sensor are derived and analyzed theoretically. The investigation results show that the linear birefringence will modify the scale factor of the system with a sample function; it can also affect the extent of the influence of the incident polarizing angle, at the same time. When the incident polarizing angle has some special values such as 0, 45, or 90 degree, its effect to the system will be zero. These results might provide some useful reference to the researchers and designers of bulk glass optical current sensors.