Soon after, it was recognized that there is an intrinsic bandwidth limitation for the cloak devices [
26]. As an attempt to broaden the bandwidth, other technologies such as conformal transformation and carpet cloak have been proposed by Li and Pendry [
27]. In general, there are mainly two researching directions. On the one hand, the transformation optics have been extended to other fields such as acoustic waves and heats [
28,
29]. On the other hand, there are extensive researches devoted to carpet cloaks in the visible regime (Figs. 2(b)-2(d)), which transform a small bump into a flat mirror to camouflage [
23–
25]. More recently, metasurface-based surface cloaks and related technology are demonstrated by various groups [
30,
31]. However, although these technologies seem to greatly reduce the detection probability by enemies [
31], the perfect cloaking condition was only met at one single wavelength [
30]. To obtain broadband surface cloaking with metasurface, the chromatic dispersion should be addressed [
32,
33].