This project explores the design and analysis of light-controllable genetic circuits, extending classical models like the toggle switch and repressilator. By integrating tunable light-based regulation into gene expression systems, we developed two models; a direct opto-repressilator where light modulates promoter activity, and a protein-mediated opto-repression system that more closely mimics biological reality. Using differential equation modeling, bifurcation analysis, and dynamic simulations, we examined the stability and controllability of these circuits. This work showcases how light can be used to precisely tune synthetic biological behavior and offers new insights into designing responsive, programmable gene networks with Python-based visualization tools.