A backlight unit and a display device including the backlight unit are discussed. According to an embodiment, a light generating device comprising: arrays of light source devices arranged on a first layer and including a first light source device and a second light source device configured emit light in opposite directions, at least one of the first and second light source devices including: a housing having inclined inner walls that define a cavity, a light emitting diode disposed in the cavity and configured to generate the light, and at least one material filled in the cavity; a reflection layer disposed on the first layer and configured to reflect the light emitted from the light source devices; and a second layer covering the light source devices and the reflection layer.