In this manuscript, an all-optical modulation photodetector based on a CdS/graphene/Ge sandwich structure is designed. In the presence of the modulation (near-infrared) light, the Fermi level of the graphene channel shifts, allowing for the tuning of the visible light response speed as well as achieving a broad responsivity range from negative (-3376 A/W) to positive (3584 A/W) response. Based on this, logical operations are performed by adjusting the power of the modulation light superimposed with the signal light. This facilitates more covert, all-optical, high-speed encrypted communication. The ultrahigh tunability and nearly symmetric positive and negative photoconductivity of all-optical modulation photodetectors significantly enhance the computational capacity of neuromorphic hardware. The proposed device exhibits substantial advantages in applications requiring high fault tolerance for integrated sensing-computing （ISC） and high-resolution motion object recognition, providing insights for the development of next-generation high-bandwidth, low-power-consumption ISC devices.