NOVELTY - The apparatus has optically transparent sections comprising optical media with an index of refraction, respectively, where an interface between the optically transparent sections defines a bi-conic shape. The shape and the indices of refractions are configured such that light entering a tapered core (108) is deflected at the interface at an angle, and the light impinges on the interface between the core and a cladding at an angle is equal to a critical angle for total internal reflection when the light impinges on a core-cladding interface.    USE - Light guide apparatus e.g. side pumped optical pipe, optical fiber and planar solar concentrator, for redirecting a propagation of a light beam in a solar panel (claimed) for a water heater. Can also be used for power producing smart window, indoor lighting application and solar thermal.    ADVANTAGE - The apparatus redirects the light impinging on the apparatus over a wide range of incident angles and concentrates the light without using a tracking system. The apparatus allows the angles of faces of a prismatic heterogeneous interface to be proportionally increased when the angle from horizontal of the incident light on the planar core is increased, thus ensuring that the light is trapped and propagates in the core without loss. The apparatus achieves a high thermodynamic efficiency at a higher temperature of a tube, thus operating the water heater in an efficient manner. The apparatus allows the angle of the conical interface to be steep such that a heterogeneous interface boundary is reduced to a point in quick manner.    DETAILED DESCRIPTION - The optical media are air and vacuum. The interface has one of a conic shape, a semi-conic shape, a parabolic conic shape and an ellipsoidal shape. INDEPENDENT CLAIMS are also included for the following:    (1) a solar panel    (2) a method for fabricating a light guide assembly.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a light guide apparatus including a core and a cladding layer.    Cladding layer (104)    Air inclusion (106)    Tapered core (108)    Longitudinal axis (110)    Radial axis (112)