Signatures of enhanced superconducting phase coherence through MID-IR excitation in optimally doped Y-Bi2212

Optimally doped cuprate superconductors are characterized by the presence of superconducting fluctuations in a relatively large temperature region above the critical transition temperature. We reveal here that the effect of thermal disorder, which decreases the condensate phase coherence at equilibrium, can be dynamically contrasted by photoexcitation with ultrashort mid-infrared pulses. In particular, our findings reveal that light pulses with photon energy comparable to the amplitude of the superconducting gap and polarized in plane along the copper-copper direction [110] can dynamically enhance the optical response which is associated to the onset of superconductivity. We propose that this effect could be rationalized by an effective d-wave BCS model, which reveals that mid-infrared pulses result in a transient increase of the phase coherence.