A structure of light emitting diode (LED) effectively reduces its spectral
width. The LED structure is applied in a three color mixing of a
backlight module to broaden a color space and to improve a saturation of
a color display. A grating structure is used as a waveguide layer to
coordinate with the LED structure. The present invention does not affect
the original thermo and electrical characteristics of the LED structure
and has a simple fabrication method.