We note that various “trapped rainbow” guiding schemes have been already experimentally demonstrated at microwave12–14 or even at visible16, 18, 36, 37 frequencies. However in such waveguide or grating based structures, the modal volume of the localized wave is inevitably restricted by the volume of the defect waveguide or the width of the tapered grating. Such a limitation impose severe constraint onto the local field intensity and the available volume at which the spectrally resolved wave can be efficiently harvested. In this manuscript, on the other hand, we show that the “trapped rainbow” effect occurring in a defect free bulk structure can lead to considerable higher local field intensities by employing 3D PhC bulk modes with large modal volumes.