PACS 78. 45.+h, 78.55.Cr, 78.67.De, 81.15.Gh InGaN/GaN and GaN/AlGaN MQW waveguides were fabricated on a (1-101) GaN facet grown on a 7-degree off oriented (001) Si substrates by MOVPE. We achieved uniform layers with less dislocation density and superior flatness by virtue of the low growth rate on the facet. Using a nitrogen laser as the excitation source, the optical gain spectra as a waveguide was evaluated. In the InGaN/GaN MQW structure, we found that the optical gain was as high as +40cm -1 at near band edge emission peak. The GaN edge emission peak showed narrowing by high intensity excitation: the full width at half-maximum 1.8 nm at under 4.5 MW/cm 2 at 77 K.