Researchers at Alberta University in Canada succeeded in generating green light through the third harmonic with insulated silicon nano-plasma waveguides. The third harmonic generation device is excited by a 1550 nm laser and is processed by a gold layer waveguide with a height of 340 nm, a width of 95 nm and a thickness of 60 nm which is processed on an insulating silicon substrate to finally output a green light of 517 nm at the output end.
It is known that silicon is the material with the highest third-order nonlinearity and the highest refractive index of all CMOS materials. It is usually difficult to emit light in the visible wavelength band because the silicon band gap is not straight and any visible light generated is strongly absorbed. To overcome these obstacles, the waveguide utilizes its internal surface-to-plasma mode light-matter coupling and a strong local infrared electric field to achieve effective nonlinear light mixing and short distances [than green light at about 700 nm for silicon Absorption of short length] within the third harmonic occurs. Waveguides are capable of producing broadband visible light by energetically accelerating the light in a steep gradient field at the silicon-copper interface to excite electrons and driving the electronic avalanche multiplier and impact ionization processes in a strong nanosphere.