The growth of crystalline 1D nanowires of semiconductors on non-epitaxial surfaces holds the promise to overcome many of the current challenges of heteroepitaxial material synthesis and device fabrication for a wide range of electronic and photonic applications. Nano-heteroepitaxial bridging of CVD grown nanowires potentially enables a low cost and mass-manufacturable approach to nanowire based device fabrication. Here we report the synthesis and bridging of lateral silicon nanowires between a pair of vertical non-single crystal surfaces and application of this technique in the design and fabrication of waveguide-integrated photodetectors. The device consists of a number of 1D nanowires laterally grown across gaps etched into rib optical waveguides with an amorphous silicon oxynitride core and silicon oxide claddings. A pair of phosphorous-doped polysilicon electrodes was deposited on the walls of the waveguide gap for electrical interfacing of the nanowires to collect the photocurrent under optical excitation. Characterization results demonstrated good waveguide characteristics, high electrical isolation between the electrodes, low leakage current and distinct photoresponse from the bridged nanowires. This implementation of silicon nanowires on polysilicon combines the characteristics of crystalline 1D nanowires with the flexible fabrication processes on non-single-crystal silicon platforms facilitating advances in silicon photonics and beyond. © 2009 SPIE.