K. Ujihara et al., NONCONFORMITY OF PLANAR MICROCAVITY DYE-LASERS WITH SCHAWLOW-TOWNES LAW, Progress in crystal growth and characterization of materials, 33(1-3), 1996, pp. 179-182
The experimental rsults concerning the spectral width and angular dive
rgence as well as the mode radius of planar microcavity dye lasers are
in agreement with theory for below threshold, but are in discrepancy
above threshold with the active mode theory based on the Schawlow-Town
es formula.