However, the monolithic structure described here offers advantages for devices which operate via light focused through an optical objective lens, such as a PCA-based THz emitter. One advantage is that a monolithic structure can be placed strategically with a high-quality area of the photonic structure commensurate with the stimulating laser pulse. The structure of the core-shell monolith can be fabricated precisely to match optical resonances with the wavelength of the stimulating laser and optical properties of the absorber. The light concentrating structure can be fabricated independently of the absorber layer, which may not have compatible chemistry with the nanosphere deposition chemistry or ALD processing conditions. Finally, in some cases the absorber in the PCA device may have anisotropic optical properties which require a preferred relative orientation between the resonant photonic structure and the absorber material.