The third-order intensity cumulants of a multimode Ar-ion laser have b
een studied. Scatter plots obtained between second-and third-order cum
ulants of the multimode laser were found to be quite different from th
ose of singlemode laser light and of a classical mixture of thermal an
d coherent light. For the first time, negative third-order cumulants h
ave been observed in the normal oscillating condition. (C) 1997 Elsevi
er Science B.V.