2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/93975We propose a simple test to demonstrate and detect the presence of vacuum inducde coherence in a $Λ$-system. We show that the probe field absorption is modulated due to the presence of such a coherence which is unobservable in fluorescence. We present analytical and numerical results for the modulated absorption, the cosine and sine components of which display different types of behavior.9 pages, 4 postscript files. Submitted for the special issue of "Laser Physics" on "Lasing without inversion and Interference phenomena in Atomic systems", Vol 9, #3, 1999Quantum Physicstext