“…The SQM leads a quantized phase distribution gradually by extending the quantization area as the iteration process proceeding. 1 " In the design procedure for DPEs, we used the same parameters for SQM as described in Ref. 10; that is, Q=5, P=10, and 5(1) = 0.3, 6(2) = 0.5, E(3) = 0.6, E(4) = 0.7, 5(5) = 0.75, E(6) = 0.8, 5(7) = 0.85, 5(8) = 0.9, 5(9) = 0.95, and 5(10) = 1.0, where Q is the number of iteration in each subdivided cycle in which the quantization area is fixed, P is the total number of subdivided iteration cycles, and c(P) indicates ratio of a quantization area to the total area in the pth subdivided iteration cycle.…”