  Coherent Perfect Absorber (CPA) and Laser is a pair of inversely worked wave
structure satisfying the time-reversal relation. We point out that, if the wave
energy absorbed by CPA can be recovered by somewhat way and then be reemitted
by its corresponded Laser, their combination can be a wave-controlling device
that can "move" the wave energy from one place to another. By extending the
concepts of CPA and Laser from the previously studied one-dimensional
non-Hermitian systems to the two-dimensional ones, this understanding is used
to simplify the designing of the metasurface in this letter. As examples, an
angular-asymmetric transmitting metasurface and wave splitter, which acts as
perfect transmitter/retro-reflector for waves coming from two oppositely tilted
angles and split an incident wave into two directions with arbitrary amplitude
ratio and phase difference, respectively, are constructed by combining two
pieces of the separately designed CPAs. The idea can not only greatly simplify
the designing of metasurface, but also bridge the researches between the
metasurface and non-Hermitian system.
