An optical system is provided which includes a light source which outputs light; a first waveguide; a transmissive reflective layer provided on a top surface of the first waveguide and configured to reflect some light and transmit the remaining light incident thereon; a second waveguide provided on a top surface of the transmissive reflective layer; an in-coupler provided on the first waveguide and configured to allow the light output by the light source to enter the first waveguide; and an out-coupler provided on one of the first waveguide and the second waveguide and configured to emit light from the optical system.