Method and device for forming optical waveguide in air by ultra-short pulsed intense laser

Abstract

The invention provides a method and device for forming an optical waveguide in air by an ultra-short pulsed intense laser. To be specific, the method comprises: a beam shaping device and a focusing lens are arranged at an output terminal of an ultra-short pulse laser along an axis direction; a laser beam passing through the beam shaping device forms a laser beam with a hollow conical shape and thelaser beam is transmitted independently, wherein the cross section intensity is in circular-ring distribution; and when the laser beam passes the focusing lens, an annular light spot is formed at thefocusing plane and an annular symmetric filament is generated based on a non-linear effect. When the filament is formed, air ionization is caused by the intense laser and thus plasma is generated; and the plasma is a heat source and the air density of the ionized region is low and thus the refractive index is low. Comparatively speaking, the air density inside the cylinder as a non-ionization region is high and thus the refractive index is high, so that a cylindrical symmetric optical waveguide structure is formed. Because the thermal conductivity of air is low and the time needed by thermalbalancing is at an ms order or longer, an optical waveguide with the millisecond service life is formed. Besides, the optical waveguide can be used for transmitting laser beams with different modes bycontrolling a circular ring distribution parameter of the pulse laser.

Description

technical field [0001] The invention belongs to the technical field of ultrashort pulse laser, and in particular relates to a method for forming an optical waveguide in air by using ultrashort pulse intense laser and a device for realizing the waveguide. Background technique [0002] Due to the characteristics of ultrashort pulse intense laser with narrow pulse width and high peak power, it will cause strong nonlinear effects when transmitted in the medium. It is worth mentioning that the filamentation process of ultrafast pulsed intense laser in the medium is accompanied by rich nonlinear processes such as THz radiation, self-phase modulation and ultra-broadband continuous white spectrum, which are useful in remote detection, weather control, optical waveguide, etc. And other fields have important application prospects, and have become an important research direction in the field of ultrashort pulse intense laser research. [0003] Ultrafast laser filamentation is a unique...

AI Technical Summary

Problems solved by technology

In order to improve the transmission efficiency, it is necessary to use more optical filaments (such as 6 or 8) to produce a thermal waveguide with a relatively "complete outer wall", which undoubtedly increases the difficulty of manipulation

Images