A microfluidic chip that incorporates colloidal crystals inside a microchannel system for on-chip integration of optical components is presented. It is demonstrated that the use of fluorescent spheres offers added advantages and functionality to the colloidal crystal array. Multifunctional optical components are demonstrated that are able to serve as a reference wavelength calibration line in measured reflectance spectra. Integrating colloidal crystals with varying filtering effects into a microfluidic chip enables selective transmission or blocking of a particular range of wavelengths locally. In addition, combinations of double-band colloidal crystal filters provide further tunability of the working wavelength for on-chip detection applications.