  We predict that illumination by a plane electromagnetic wave of optically
resonant membranes, such as graphene or monolayers of transition metal
dichalcogenides, directly affects their mechanical tension. The induced
optomechanical tension is anisotropic and, depending on the spectral detuning
from the resonance, can be both positive and negative. In the latter case, it
can overcome the bending rigidity of the membrane leading to transition to the
crumpled phase. The instability caused by optomechanical heating of flexural
vibrations is also considered.
