A data driver includes a gamma voltage generator that generates red, green, and blue gamma voltages according to red, green, and blue adjustment signals, and a digital to analog converter that converts data signals received from a latch to positive or negative analog video signals using the red, green, and blue gamma voltages received from the gamma voltage generator. The light emitting units include light guide portions that guide light emitted by the semiconductor light emitting elements so that light emitted by the semiconductor light emitting elements is not directed at irradiation regions of adjacent light emitting units. The free spectral range characteristics of the resonators are successively increased by an even multiple to achieve the slicing effect.