Physicists can study the possible time delays of light-induced tunneling of an electron from an atom after conducting measurements of time delays when cold atoms tunnel through an optically created potential barrier. In a new report now published in Nature Physics, Ihar Babushkin and a research team in Germany, complemented photo-electron detection in laser-induced tunneling by measuring light emitted by the tunneling electron, known as Brunel radiation. Based on combined single and two-color driving fields, they identified all-optical signatures of reshaping tunneling wave-packets as they emerged from the tunneling barrier and moved away from the core. This reshaping led to an effective time-delay and time-reversal symmetry of the ionization process, described in theory, for experimental observation. The all-optical detection method can facilitate time-resolved measurements of optical-tunneling in condensed matter systems at the attosecond time-scale.