  The ultrafast manipulation of quantum material has led to many novel and
significant discoveries. Among them, the light-induced transient
superconductivity in cuprates achieved by melting competing stripe orders
represents a highly appealing accomplishment. However, recent investigations
have shown that the notion of photoinduced superconductivity remains a topic of
controversy, and its elucidation solely through c-axis time-resolved terahertz
spectroscopy remains an arduous task. Here, we measure the in-plane and
out-of-plane transient terahertz responses simultaneously in the stripe-ordered
non-superconducting La$_{2-x}$Ba$_{x}$CuO$_4$ after near-infrared excitations.
We find that although a pump-induced reflectivity edge appears in the c-axis
reflectance spectrum, the reflectivity along the CuO$_2$ planes decreases
simultaneously, indicating an enhancement in the scattering rate of
quasiparticles. This in-plane transient response is clearly distinct from the
features associated with superconducting condensation. Therefore, we conclude
the out-of-plane transient responses cannot be explained by an equivalent of
Josephson tunneling. Notably, those pump-induced terahertz responses remain
consistent even when we vary the near-infrared optical pump wavelengths and
hole concentrations. Our results provide a critical evidence that transient
three-dimensional superconductivity cannot be induced by melting the competing
stripe orders with pump pulses whose photon energy is much higher than the
superconducting gap of cuprates.
