A light emitting device, comprising: an excitation light source, for generating an excitation light; a first supplemental laser source, for generating a first light; a wavelength conversion device, including a wavelength conversion layer adapted to absorb the excitation light to generate a converted light, without absorbing the first light, wherein the wavelength conversion layer is adapted to receive the excitation light and the first light on one side of the wavelength conversion player, and wherein the wavelength conversion layer is further adapted to output, from the same side of the wavelength conversion layer (i) at least a part of the first light and at least a part of the converted light, or (ii) at least a part of the first light and at least a part of a combined light of the converted light and un-absorbed excitation light; a light guiding device, including a first region and a second region, the size of the first region being smaller than that of the second region, wherein the first light is incident, along a first optical path, on the first region, and is directed to the wavelength conversion device by the first region, wherein the excitation light is incident, along the first optical path, on at least the second region of the light guiding device, and is directed to the wavelength conversion device by at least the second region, and wherein the second region of the light guiding device is further adapted to direct at least the part of the converted light and at least the part of the first light from the wavelength conversion device to a second optical path to be output. an excitation light source, for generating an excitation light; a first supplemental laser source, for generating a first light; a wavelength conversion device, including a wavelength conversion layer adapted to absorb the excitation light to generate a converted light, without absorbing the first light, wherein the wavelength conversion layer is adapted to receive the excitation light and the first light on one side of the wavelength conversion player, and wherein the wavelength conversion layer is further adapted to output, from the same side of the wavelength conversion layer (i) at least a part of the first light and at least a part of the converted light, or (ii) at least a part of the first light and at least a part of a combined light of the converted light and un-absorbed excitation light; (i) at least a part of the first light and at least a part of the converted light, or (ii) at least a part of the first light and at least a part of a combined light of the converted light and un-absorbed excitation light; a light guiding device, including a first region and a second region, the size of the first region being smaller than that of the second region, wherein the first light is incident, along a first optical path, on the first region, and is directed to the wavelength conversion device by the first region, wherein the excitation light is incident, along the first optical path, on at least the second region of the light guiding device, and is directed to the wavelength conversion device by at least the second region, and wherein the second region of the light guiding device is further adapted to direct at least the part of the converted light and at least the part of the first light from the wavelength conversion device to a second optical path to be output.