An optical excitation device for exciting a laser light source includes a wavelength converter and a moving element. The laser light source emits a first light beam. The wavelength converter includes a wheel, a motor connected to the wheel, and a wavelength converting layer disposed on a light receiving surface of the wheel for converting the first light beam with the first wavelength into a second light beam with a second wavelength. The moving element is connected to the wavelength converter for moving the wavelength converter relative to the laser light source. There is a first reaction area between the laser light source and the wavelength converter when only the motor is operated, there is a second reaction area between the laser light source and the wavelength converter when both the motor and the moving element are operated, and the second reaction area is greater than the first reaction area.