Fig. 13

Scheme of 2D EPE. a Schematic of IDA 2D EPE. b Corresponding normalized \(k\)-vector diagram of the IDA 2D EPE scheme, where \({\bar{G}}_{in}, {\bar{G}}_{f1} \; \text{and}\; {\bar{G}}_{f2}\) represent the normalized \(k\)-vector of the in-coupling grating, folding grating 1, and folding grating 2, respectively. (c) Schematic of 2D EPE utilizing four grating sequences. d Schematic of the first 2D EPE and FoV expansion in c. e Schematic of the second 2D EPE and FoV expansion in c. Corresponding normalized \(k\)-vector diagram of the f first and g second 2D EPE scheme and FoV expansion. Black dashed arrows in b, f and g correspond to the normalized grating \(k\)-vector. The coral regions in b, f and g correspond to all normalized \(k\)-vector within the system FoV