A novel architecture of one-dimensional photonic crystal membrane (PCM) reflectors embodying a heterostructure is proposed as a robust design aimed at a 3-D efficient confinement of light in single-mode polarization-controlled 1.55-μm vertical-cavity surface-emitting laser (VCSEL) microsources for heterogeneous integration on complementary metal-oxide-semiconductor (CMOS). On the basis of a theoretical approach, the paper focuses on the deep interweaving between the kinetics of light transport in the mirrors and the physical nature of the exploited Fano resonances. An example of VCSEL design for optical pumping employing heterostructure-confined photonic crystal mirrors is presented. The predicted photons kinetics along with the considerable improvement in cavity modal features owing to the enhanced mirror architecture have been confirmed by performing rigorous three-dimensional finite-difference time-domain (3-D FDTD) calculations. Finally, experimental observations of photoluminescence (PL) emission performed on first-ever fabricated devices for optical pumping show striking agreement with theoretical considerations and ab initio modelling.