Tunable CW laser action of platelet semiconductors is reported in both mode-locked and unmode-locked configurations. The gain media are platelets of CdS, CdSe, CdSSe and InGaAsP, cooled to 85K and longitudinally pumped by argon-ion and krypton-ion lasers. Anti-reflection coating of the crystal face and external bandwidth restriction have been used to generate pulses as short as 4 ps in CdS. The pulses observed are chirped, with non-transform limited time-bandwidth products of about 1.7. The energy conversion efficiency is 20% into the TEMoo mode, with output powers of over 10 mW from CdS. Pulses as short as 7 ps tunable over a 26 nm range have been obtained in InGaAsP.