111 this work ail analysis of gain in single c|iianliini well last'rs as a riinction of sonu' of llu'ir o|)(M’alioiial paranu'l('rs is earrii'd oiil. I^'irsl, a 1 li('or('liea.l inodi'l of gain is |)resent('d. 'riuMi two diderent nudliods of gain iiK'asiir('in('nt, wliieli iis(' the spontaneous emission IVom the iaec't and the nnamplified s[)ontan('ons ('mission from the top of the ridg(', arc' discussed. Indirication procc'sses of lasers to racilitate tJie colh'clion of unampliiic'd spontaiK'ous ('mission are ch'tailed. R('S|)onse of the gain sp('ctrum to chang('s in inject('d cnrr('nt (h'lisity and temperature are measur('d and iinderstood in terms of hand Idling, hand gap renormalization and tenpx'rature d('pendenc(' of tlu' handgap. (!ain sainration above threshold is v('ri(ied and s|)atial variations in spontaiu'ons ('mission in lh(' longitiidnal and hiteral directions are observed.