Coupling of one-dimensionally confined optical modes in porous silicon: Spectral observation and photonic-quantum-well description

Single and double photonic-quantum-wells (PQWs) have been fabricated, using refractive-index-modulated porous silicon multilayer structures. The one-dimensionally confined optical modes observed are consistent with those calculated using the transfer matrix method. While single PQWs exhibit atom-like discrete spectral features, molecule-like energy level splitting is accessible by combining two single PQWs into a double PQW structure. Similar to an electron in a double-quantum-well structure, the energy separation between the split ‘anti-bonding’ and ‘bonding’ photonic states can be ‘tuned’ by changing the strength of inter-well coupling.