Abstract: A cooling system includes a first stage heat reservoir arranged to absorb heat from a heat source. Heat is transferred from the first stage heat reservoir to a second stage heat reservoir. The first stage heat reservoir includes a material with a heat capacity lower than that of the second stage heat reservoir but with a thermal conductivity higher than that of the second stage heat reservoir. Heat transfer structure increases heat transfer rate from the first stage heat reservoir to the second stage heat reservoir.

Abstract: 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.