Ion irradiation was used to pattern a region of red‐light emitting porous silicon by eliminating visible‐light photoluminescence (PL). The PL peak wavelength is approximately 735 nm and shows little dependence on the excitation‐light wavelength. The ratio of PL intensities for different excitation wavelengths was shown to be proportional to the ratio of the absorption coefficients. Below saturation, the integrated PL intensity increased linearly with excitation‐light power density.