Coherent THz emission from optically pumped parabolic quantum wells

Summary form only given. Several mechanisms for coherent THz emission from both semiconductor bulk and heterostructure devices have been presented. Recently, Sekine et al. reported on the optically pumped emission of THz radiation from grating-coupled intersubband plasmons in a doped single quantum well. We present experiments which show that modulation doped parabolic quantum wells (PQWs) emit coherent THz radiation corresponding to the intersubband plasmon when excited by near infrared femtosecond laser pulses.