The present invention relates to an apparatus and methods for achieving phase-matching between various waves and/or modes by operation of a waveguide. Phase-matching between interacting waves is achieved by total internal reflection and transverse Bragg reflection waveguides. Using second harmonic generation in GaAs/AlGaAs as an example, properties are investigated and quantified such as nonlinear coupling efficiency, bandwidth, tunability, and limitations due to dispersion. The technique is advantageous when compared to alternate technologies, where it is particularly attractive as a material independent means to obtain ultra-low-loss nonlinear optical elements for monolithic integration with coherent light source and other active devices.