ABSTRACT
This study investigates the possibility that a crack pair that is naturally formed in the course of sample preparation functions as a laser cavity. Lasing with longitudinal mode structures has been reported in mixed-crystal thin films composed of fluorene and anthracene without artificial cavity structure. In the present study, it was shown that lasing is observed only when an excitation spot covers parallel pairs of cracks. The longitudinal mode intervals of the stimulated emission spectra for several crack pairs were found to be proportional to the inverse of the crack spacing. Furthermore, the interval for the artificially fabricated metal cavity followed the same linear relation. These results indicate that the crack pairs can function as laser cavities.
ABSTRACT
The potential for room-temperature lasing in densely doped organic crystals has been examined using (fluorene)0.8-(anthracene)0.2 thin crystals fabricated in a narrow gap between two quartz plates. An excitation-intensity dependence study confirms that the system shows spectral line narrowing, a super linear increase of the narrow line above threshold excitation intensity, and laser cavity modes. These results indicate that lasing has been observed in the densely doped organic crystal, which contains in-plane cavities with a length of approximately 100 µm.
