Optoelectronics Coating Boasts High Refractive Index

Fiber Optic Center, Inc., (FOC) introduces High Refractive Index Coating for Optoelectronics, LEDs, Emissive displays, AL-2264. The product is an optical polymer dissolved in an evaporative solvent that can be applied by simple methods, i.e. dip, spin coating, drawdown, printing, etc.  Upon drying it creates a hard, durable, polymer coating with a refractive index of 1.64.  This polymer contains no metals, and the product contains no nanoparticles.  The standard concentration leaves behind an approximately 20u layer coating thickness (using a single dip coating process).  Coating thickness is easily reduced by diluting the standard concentration with the compatible solvent.  The solvent is easily removed by baking at 100°C for 15 minutes.  


Optically clear, high refractive index coatings can be used to improve the performance of light gathering/dispersing devices.  Many solid state optical devices, i.e. imaging/optical sensors, emissive displays, LEDs, are made of light emitting semiconductors with significantly higher refractive indices (>2) than air (1.0).  Light is partially reflected when it encounters a sudden difference of refractive index.  Light transmission at such boundaries is improved with a layer of an intermediate refractive index material, thus improving the optical efficiency of the device – effectively raising the numerical aperture (NA) of the optical system.  For semiconductors and air, that desirable refractive index is in the >1.6 range.   Additionally in this case, the ‘air’ side of the coating directly contacts the environment and must be protective: hardness and durability are required; chemical resistance is a plus.  


Fiber Optic Center, Inc.

New Bedford, MA