Plasmonic Illumination Device Anisotropic Light Directionality

A scattering layer is introduced as an intermediary component between the LED and the wavelength converting material. This scattering layer is positioned at a specific distance from the LED surface, allowing it to scatter the converted light uniformly in all directions while preventing direct contact between the scattering material and the LED, thereby avoiding backscattering of blue light into the LED and reducing absorption losses.

The solution transitions from a two-dimensional planar arrangement (LED chip with phosphor directly on top) to a three-dimensional structure by introducing a scattering layer at a specific height above the LED. This vertical dimensionality allows the scattering function to be separated from the conversion function, enabling independent optimization of both color uniformity and efficiency.

The patent replaces complex photonic band gap structures with a simple scattering layer made from conventional, inexpensive materials. Instead of requiring precise nanoscale fabrication of high aspect ratio holes or pillars in luminescent materials, the solution uses a relatively thick scattering layer that can be manufactured using standard, cost-effective techniques. This achieves comparable or superior directionality control without the manufacturing complexity.

The solution changes the key parameter from nanoscale structural geometry (high aspect ratio holes, precise lattice constants) to macroscopic material properties (scattering coefficient, layer thickness). This parameter transformation allows achieving similar optical effects using conventional materials and manufacturing processes rather than requiring precise nanoscale structuring.