We present recent works on the construction of high-frequency solutions to Einstein vacuum equations in general relativity, based [Tou22b, Tou23]. In these articles, author shows existence a family spacetimes (g λ ) λ∈(0,1] generalised wave gauge oscillating at frequency -1 and defined by geometric optics ansatz. this survey, we first review Cauchy theory for gauge, Burnett’s conjecture relativ...