An RGB laser light source module combines Red, Green, and Blue laser lights into a single beam, allowing for the representation of various colors by mixing the emission colors of each laser. This light source is intended for use in devices such as smart glasses, and development efforts are focused on achieving high performance in a compact size. Currently, optical systems are used to mix the light, but there are limits to miniaturizing these systems. In this work, we developed the world's smallest RGB laser light source module by emplying an optical waveguide structure on a silicon substrate and coupling the RGB laser lights to it to mix the light within the waveguide.

In order to project clear images using lasers, it is necessary to mix three colors of light - Red, Green, and Blue - to express various colors. This is demanded for applications such as smart glasses, which require high performance in a more compact size. Currently, light is mixed using spatial optical systems combining beam splitters and mirrors, but there is a limit to reducing the size of such optical systems. Figure 1(a) shows a PLC (Planar Lightwave Circuit) combiner chip fabricated using MEMS processes such as deep etching. To control light in a fine area, using an optical waveguide structure is feasible. In this development, we successfully developed a PLC combiner chip that can combine Red, Green, and Blue laser light by fabricating an optical waveguide structure on a silicon substrate and coupling each laser light. The light can be mixed within the waveguide. Furthermore, we have developed the world's smallest class RGB laser light source module shown in Figure 1(c), which packages the PLC combiner chip and laser chip.

RGB laser light source modules can be used in various applications such as industrial light sources, lighting sources, smart glasses, head-up displays, microprojectors, and retinal projection microprojectors. KODENSHI has developed a demo device for smart glasses and laser signage projectors that incorporate this module and is proposing it to various industries.