While naively laser only allow to excite external target, for example STED microscopy demonstrates it can also cause its deexitation, however, under uncommon condition of being prepared as excited. These two causations are governed by stimulated emission-absorption pair of equations, and there are presented many arguments that they are switched in perspective of CPT symmetry, however, it would mean photon direction opposite to usually assumed. This article discusses these arguments and proposes simple STED-like tests to experimentally determine this direction once for all, to be performed in a near future. Depending on its result: it should lead to new applications like 2WQC more symmetric quantum computers, or macroscopic violation of CPT symmetry, so far tested only in microscopic settings. Also forward/backward/bidirectional photon sources are discussed.