Emergence of light-induced superconducting-like state from the charge density wave state in high-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>T</mml:mi><mml:mi>c</mml:mi></mml:msub></mml:math> cuprate superconductors

A comprehensive study of light-induced superconducting-like response in the La-based cuprate superconductors ${\mathrm{La}}_{2\ensuremath{-}x\ensuremath{-}y}\phantom{\rule{0}{0ex}}{\mathrm{Nd}}_{y}\phantom{\rule{0}{0ex}}{\mathrm{Sr}}_{x}\phantom{\rule{0}{0ex}}{\mathrm{CuO}}_{4}$ and its correlation with the charge density wave states is investigated by near-infrared optical pump and terahertz probe spectroscopy. The light-induced plasma edge appears up to far above ${T}_{\mathrm{c}}$ with the same frequency as that of the Josephson plasma resonance of ${\mathrm{La}}_{2\ensuremath{-}x}\phantom{\rule{0}{0ex}}{\mathrm{Sr}}_{x}\phantom{\rule{0}{0ex}}{\mathrm{CuO}}_{4}$ in its superconducting phase while lacking the long-range superconducting coherence, suggesting the presence of localized Cooper pairs above ${T}_{\mathrm{c}}$ that show up after photoexcitation.