Fig. 4

a Devices under test (DUT) comprising two 1D FGCs at the in- and outputs, connected by a short waveguide. Test field 1 has a waveguide length of 870 μm; test field 2 has a waveguide length of 250 μm. b Experimental setup for the FGC back-to-back characterization, including a laser source, a polarization controller, standard single-mode-fibers (SSMF) for in-and out-coupling and a power sensor