Passive mode locking andQswitching has been achieved for the first time in an Er3+:YSGG laser at &lgr;=2.8 &mgr;m using ultrathin single‐crystal InAs epilayers grown on GaAs substrate which were subsequently bombarded with 15 keV protons at a dose of 1013cm−2. The bleaching effect was due to a dynamic Moss–Burstein mechanism with a fast (<100 ps) recovery time. In the case of passive mode locking, pulses of 10 MW power were generated at &lgr;=2.8 &mgr;m.