This work shows improvements on previous results related to the integration of optical waveguides and simple light sources. These previous results showed the possibility of coupling the light emitted from an incandescent chromium filament embedded in a self-supported region of silicon oxynitride (SiO xNy) film with a SiOxNy waveguide. This specific work aims to increase optical power coupled to the waveguide through the investigation of the geometry of the microlamp. Here, the length of the incandescent light is analyzed. The waveguide are fabricated on a (100) silicon substrate using silicon oxynitride deposited by PECVD as the core and cladding layers. Bulk micromachining of the silicon substrate in KOH solution is used to free from the substrate the embedded filament, reducing the thermal dissipation of that region, allowing the filament to heat up to incandescent temperatures. A microannealing process of a PECVD-obtained amorphous hydrogenated silicon carbide (a-SiC:H) deposited over the microlamp allows the correct coupling of the light. © 2009 SPIE.