We present the first demonstration of a tightly coupled array (TCA) excited by high-power photodiodes directly integrated onto the antenna substrate. As a complex electrical feed network is not required to feed the radiating elements, the design can realize ultra-wide bandwidth while improving upon the size, weight, and power of conventional electronic-based arrays. Circuit and full-wave simulations are conducted for optimization of array performance and compared against all-electronic TCA designs within the literature. A prototype $9\times 12$ element TCA with four photodiode-integrated active elements is characterized to validate the design process. The photonic array exhibits high radiation efficiency between 5 and 20 GHz, and a maximum effective isotropic radiated power of 25 dBm at 13 GHz is measured in the far field.