InGaAs/InGaAsP quantum wells microdisk lasers 0.8 mum in radius and 0.
18 mum thick with emission at lambda = 1.542 mum can be fabricated and
operated at room temperature. Optical mode spacing in such structures
is so large that a significant fraction (approximately 20%) of sponta
neous emission feeds into the lasing line resulting in superlinear out
put over a wide pump range.