Low threshold Brillouin active devices

摘要

A non-linear optics device (NLOD) of the kind in which an incoming pumping beam having an intensity below a certain threshold is transmitted through the device, whereas a beam having an intensity above the threshold induces a Stimulated Brillouin Scatter (SBS) process giving rise to the reflection back of the beam in an opposite direction. The device includes one or more optical fibers having each a cladding and a core consisting of a non-linear substance which, as a rule, is composed of two longitudinal sections integral with one another, one having a uniform diameter and the other being tapered. The core surface is diverged towards one end of the fiber. Each optical fiber is so oriented that the end of the tapering section faces the incoming pumping beam. Accordingly, when an oncoming pumping beam is incident on the surface of the tapering core portion at an angle below a certain critical angle, it is transmitted to the uniform core section.