Apparatus for enhancing on-chip fluorescence detection. For example, an apparatus comprises a microfluidic channel, an excitation signal enhancing structure formed on a first side of the microfluidic channel and a photodetector structure formed on a second side of the microfluidic channel. For example, the excitation signal enhancing structure enhances an excitation signal and the enhanced excitation signal excites one or more samples in the microfluidic channel to emit signals at a fluorescence wavelength at a higher rate.