NOVELTY - Enhanced optical coupling arrangement comprises: an optical coupler device operative to direct light incident, and having a planar surface on it; and a piano-piano optical element (10) whose first surface is mounted in light receptive relationship to the planar surface of the optical coupler device. The piano-piano optical element comprises a body (12) having a first portion (14A) and a second portion (14B), where the first portion is formed from a first material having an index of refraction n1, and the second portion is formed from a second material having an index of refraction n2.    USE - The optical coupling arrangement is useful in integrated photovoltaic cell assembly, photovoltaic module and concentrating photovoltaic system (all claimed).    ADVANTAGE - The optical coupling arrangement: spatially modulates the intensity of light while exhibiting sufficient radiation durability for the application; utilizes the piano-piano optical element that enables it to be incorporated on to a diverse number of different photovoltaic (PV) cells, and then to be integrated into the rest of the PV module, without requiring redesign of the module; and can be easily incorporated with other optical elements, including secondary optics of the homogenizer or concentrator types used in concentrating photovoltaic applications.    DETAILED DESCRIPTION - Enhanced optical coupling arrangement comprises: an optical coupler device operative to direct light incident, and having a planar surface on it; and a piano-piano optical element (10) where a first surface of the optical element is mounted in light receptive relationship to the planar surface of the optical coupler device. The piano-piano optical element comprises a body (12) having a first portion (14A) and a second portion (14B), where: the first portion is formed from a first material having an index of refraction n1; the second portion is formed from a second material having an index of refraction n2; one index of refraction is greater than the other index of refraction, with both indices of refraction being greater than the index of refraction of air; each portion of the body have a substantially planar exterior surface formed on them, and each surface defines one of a pair of opposed major surfaces of the optical element; the first and second portions are arranged so that an interface (20) with at least one cusp is defined within the optical element between the first and second materials; and the cusp have an apex pointed toward the material having the greater index of refraction, and the cusp are operative to produce a region of modulated light exiting the second surface of the optical element in response to light received from the optical coupler device that is incident on the first surface of the optical element. INDEPENDENT CLAIMS are also included for:    (1) an integrated photovoltaic cell assembly comprising: the optical coupler device; a photovoltaic cell having at least one semiconductor junction operative to produce electrical energy in response to incident radiation, where the photovoltaic cell has at least one obstruction to incident light on a planar surface of it; and the piano-piano optical element whose first surface is mounted in light receptive relationship to the planar surface of the optical coupler device and second surface is mounted to the planar surface of the photovoltaic cell, where the region of modulated light exiting the second surface of the optical element is aligned with the obstruction on the photovoltaic cell while the redirected light is incident upon another region of the surface of the photovoltaic cell;    (2) a photovoltaic module comprising: a housing; a primary optics arrangement for concentrating incident light mounted to the housing; the optical coupler device disposed within the housing, and operative to direct light incident on it from the primary optics arrangement; the photovoltaic cell; and the piano-piano optical element; and    (3) a concentrating photovoltaic system comprising: a module housing; a tracker for moving the housing in tracking relationship to a light source; the primary optics arrangement; the optical coupler device; the photovoltaic cell; and the piano-piano optical element.    DESCRIPTION OF DRAWING(S) - The figure shows a stylized pictorial front section view of an optical element article.    Optical element (10)    Body (12)    First portion (14A)    Second portion (14B)    Interface (20)