Observation of Electromagnetically Induced Transparency by a Train of Short Pulses

We report the experimental demonstration of electromagnetically induced transparency in hot rubidium (⁸⁵Rb) atomic vapour by using an actively mode-locked external cavity diode laser in Littman-Metcalf configuration. We can make opaque resonant transitions transparent to any two optical comb components in the pulse trains which excite atomic coherence in the ground states of ⁸⁵Rb.