Patent ID: 7004610

Claim:
A light source device comprising: a primary light source; a light guide constituting a waveguide for transmitting a light outputted from the primary light source, having a refractive index of ng, and including a light input end face on which a light emitted from the primary light source is made incident, a light output surface for outputting a transmitted light, and a back surface positioned in a side opposite the light output surface; and a light leakage modulator attached to at least one of the light output surface and the back surface of the light guide, and including a composite layer positioned on the light output surface or the back surface and having a plurality of first refractive index regions each having a refractive index of n 1 (here, ng>n 1 ) and a plurality of second refractive index regions each having a refractive index of n 2 (here, n 2 >n 1 ), and a third refractive index layer positioned on the composite layer and having a refractive index of n 3 (here, n 3 >n 1 ).