Spectral characteristics of the radiation of artificial opal crystals in the presence of the photonic flame effect

The results of investigation of the spectral characteristics of radiation in the presence of the photonic flame effect recently discovered experimentally are presented. Radiation from a ruby laser operating in the Q-factor modulation regime with a generation wavelength of 694.3 nm is focused near the oriented surface of a globular photon crystal (artificial opal with a globule size of 230 nm) placed on a copper cold guide whose temperature is close to the liquid-nitrogen boiling point (77 K). The spectrum of long-term afterglow (with a duration of about several seconds when the duration of a pump pulse is equal to 20 ns) appearing in the photonic flame effect is detected using a fiber optic minispectrometer and consists of several comparatively narrow lines whose intensity strongly varies with the pumping power. A similar glow is observed in opal samples filled with acetone or ethanol.