Table of Contents
New fiber laser technology for nonlinear effects
A novel fiber laser technique for generating second-order nonlinear effects in materials that typically cannot accommodate them could lead to new possibilities for creating these effects for optical computing, fast data processors, and bioimaging. A team of researchers from Georgia demonstrates a technique, based on a red fiber laser, to produce the nonlinear effects.
Laser system setup and experimental design
For the laser system, they develop an array of small plasmonic gold triangles on the surface of a centrosymmetric titanium dioxide or TiO2 slab in the laboratory. Then the gold structure is illuminated with a pulse of laser beam light. The laser beam operates like an optical switch; it breaks the crystal symmetry of the material.
Electron excitation and frequency doubling.
The laser beam pulse causes the electron excitation when it is fired at the array of gold triangles on the TiO2 slab; the excitation doubles the frequency of the laser beam from a second laser system as it reflects from the amorphous TiO2 slab. The fiber laser system has already been tested and demonstrated the blue laser beam that “shows the frequency-doubled light and the green beam that controls the hot-electron migration”.
Operating principle of the fiber laser system
The operating principle of the laser system is based on the optical switch that causes the excitation of high-energy electrons inside the gold triangles; therefore, some electrons go to the titanium dioxide from the triangles’ tips. “Since the migration of electrons to the TiO2 slab primarily happens at the tips of [the] triangles, the electron migration is spatially an asymmetric process, fleetingly breaking the titanium dioxide crystal symmetry optically.”
Symmetry-breaking and material applications
The red laser beam pulse leads to an instant induced symmetry-breaking effect. It is possible to break optically the crystalline symmetry of conventionally linear materials, for example, amorphous titanium dioxide; the fiber laser system allows making a range of optical materials wider. These materials can then be employed in numerous micro- and nanotechnology applications such as high-speed optical data processors.
Control and stability of nonlinear effects
A stable, continuous-wave laser system enables to production of the nonlinear effect to last for as long as the fiber laser is turned on. It is possible to control the number of migrated electrons through the intensity of the red laser beam. More electrons appear inside the gold triangles when the intensity of the optical switch rises, and more electrons are put into the TiO2 slab.
The fiber laser system still requires future improvements, but now it already offers numerous opportunities in the field of nonlinear nanophotonics, as well as plays a crucial role in the field of quantum electron tunneling.