Short-range lattice correlation induced anomalous light transmission in photonic structures

Long-range lattice correlations are essential for forming bandgaps in electrons, phonons, and photons. Consequently, disorder has often been viewed as detrimental to bandgap formation, with the ideal system being a perfect crystal free of lattice imperfections. However, recent studies have shown that short-range lattice correlations in disordered media can produce photonic bandgaps. Here, we investigate tunable short-range lattice-correlation-induced photonic bandgaps in low-index-contrast samples with correlations extending up to 2 μm. Reflectivity measurements reveal resonant peaks and corresponding transmission dips that closely match the calculated structure factor, indicating a frequency gap. Angle- and polarization-dependent reflectivity measurements confirm a broad, scalable bandgap in good agreement with simulations, with a significant reduction in the local density of optical states. The light-transmission measurements across frequencies below, within, and above the bandgap exhibit an unexpected transmission decay due to short-range lattice correlations. The spectral-dependent transport mean free path shows strong suppression within the bandgap and enhancement near the band edges, consistent with theoretical predictions. Our results provide new insights into the role of short-range correlations and their potential for applications in emission control, structural coloration, and passive radiative cooling systems.