The authors have imprinted high aspect ratio artificial dielectric quarter wave plates (QWPs) on polymers for use at 2.6, 3.2, and 3.8 THz. The QWPs are imprinted on high density polyethylene using silicon masters. The grating period for the quarter wave plates is 60 mu m. Deep gratings of 330, 280, and 230 mu m are used to obtain a pi/2 phase retardance between TE and TM polarizations propagating through the QWPs. An inductively coupled plasma etch process was used to create the silicon masters for the imprint. A combination of heat and pressure was used for the imprinting process. Two plates, fixed in a back-to-back configuration, were used for each QWP. A highest aspect ratio (grating height/grating width) of 7 was obtained using the imprint technology. (C) 2010 American Vacuum Society. [DOI:10.1116/1.3497023]