The dichroic mirror 810 may have a thickness that is ? the peak wavelength of the shorter wavelength EL, but more complex coating designs are possible. The optimum dichroic mirror design for a specific device may depend on factors such as the geometry of the patterned sapphire and the amount of shorter-wavelength light permitted to escape from the device per application requirements. For white LED applications, the reflectivity of the dichroic mirror may be intentionally designed to be much lower than 100% to allow enough blue EL emission to escape to produce white light. As shown in FIG. 8D, light A emitted from the EL QW 210 may pass through the n-type layer 204, the PL QW 206, and the substrate 202 and may be reflected back by the dichroic mirror 810. The reflected light A may then enter the PL QW 206 and be emitted as light B, which may pass through the n-type layer 204, the substrate 202, and the dichroic mirror 810.

FIG. 8E, shows another example of forming the dichroic mirror 810 such that it extends to sides of the LED device. The dichroic mirror 810 may be formed using one or more conventional conformal deposition techniques, such as atomic layer epitaxy, sputtering or e-beam evaporation. In addition to the bottom of the substrate 202, the dichroic mirror may be formed on one or more of: sidewalls of the p-type layer 208, sidewalls of the EL QW 210, sidewalls of the n-type layer 204, sidewalls of the PL QW 206, and sidewalls of the substrate 202.