Photoinduced phase transitions and lattice deformation in two-dimensional <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>NbO</mml:mi> <mml:msub> <mml:mi>X</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> (

We present a comprehensive investigation of light-induced phase transitions and strain in two-dimensional $\mathrm{NbO}{X}_{2}$ ($X=\mathrm{Cl}$, Br, I) using first-principles calculations. In particular, we identify a light-induced ferroelectric-to-paraelectric phase transition in these 2D systems. Furthermore, we demonstrate the possibility of inducing an antiferroelectric-to-paraelectric transition under illumination. Additionally, we find that these 2D systems exhibit significant photostrictive behavior, adding a new functionality to their already notable optical properties. The ability to control and manipulate ferroelectric order in these nanoscale materials through external stimuli, such as light, holds considerable promise for the development of next-generation electronic and optoelectronic devices.