A roll-to-roll sub-wavelength grating applied for a liquid crystal backlight

A roll-to-roll imprinted optical setup consisting of a gratings upon a light bar (LB) is designed to shrink the coupling length between a point light source and a light guide for application in a mobile phone display. Grating period and shape was analyzed by investigating the relationship between the angular distributions of incident beam on the grating and the illumination characteristics of LED. The design has a potential to eliminate the brightness enhancement film (BEF) for a red-green-blue (RGB) light-emitting diode (LED) or a cold cathode fluorescent lamp (CCFL) backlight module in the LCD systems.