Researchers from Seoul National University and the University of Seoul have now designed a programmable photonic integrated circuit that can slow light whenever needed. The researchers addressed this limitation with a programmable photonic circuit that controls both the speed and shape of optical signals. CRIT selectively allows light within a particular frequency range to pass while reducing the speed at which the optical signal travels. The results suggested that the design could continue operating reliably under realistic photonic circuit conditions. The proposed platform enables real-time adjustment of both the timing and spectral properties of optical signals, addressing the limitations of fixed optical delay devices.