For optical applications using a silicon platform (e.g. optical interconnects), passive and especially active components made of silicon need to be developed. Unfortunately, the optical properties of silicon are not sensitive to electric fields, which makes active elements difficult to fabricate. In this work, we demonstrate electrically tunable mirrors that consist of a porous silicon microcavity resonator. Liquid crystal molecules are uniformly infiltrated into the porous silicon matrix to allow tuning of the microcavity resonance with an electric field. The applied electric field causes the liquid crystal molecules to change orientation, creating a change in the value of their refractive index and a shift of the resonance wavelength of the microcavity resonator. Simulations show devices could be built that exhibit a resonance with a full width at half maximum value of 2nm. The resonance can be shifted to achieve a change in reflectivity from ~0% to ~100%. Thus, the application of a small ac voltage should lead to a complete modulation of the reflected light.