Coherent electrically excited organic semiconductors: visibility of interferograms and emission linewidth.
Recently, a tandem organic light-emitting diode structure, excited electrically in the pulsed domain and confined within a double interferometric configuration, was observed to emit a low-divergence beam (approximately 1.1 times the diffraction limit) with a near-Gaussian spatial distribution. The emission originates from the laser dye Coumarin 545 T used as dopant. It has since been determined that the visibility of the interferograms, from the spatially coherent emission, is V approximately 0.90. This result is compared with the visibility obtained from a known narrow linewidth laser source (V approximately 0.95) and with various published values from the relevant literature. The significance of this result is discussed in addition to an interferometric estimate of the emission linewidth that yields Delta lambda approximately 11 nm. The present interferometric analysis indicates that the spectral component of the spatially coherent radiation is comparable with the spectral characteristics of well-known broadband dye lasers.
Duarte
F J
FJ
Interferometric Optics, Rochester, NY 14626, USA. duarte@opticsjournal.com