Nonellipsometric Noncollinear Electrooptic Sampli ng of Terahertz Waves: A Comprehensive Theory

We present an analytical model that elucidates a recently proposed (Opt. Exp., vol. ${\bf 21}$, pp. 9277, 2013) technique for nonellipsometric noncollinear electrooptic sampling of terahertz waves. In this model, an intensity modulation of the probe optical beam is consistently found as a result of noncollinear nonlinear interaction of the terahertz and probe optical beams of finite widths. The model is able to predict the output electrooptic signal for different detection conditions. We apply the model to the situation of practical interest-a LiNbO$_3$ crystal coupled to terahertz radiation with a Si prism and probed at 800 nm wavelength.