This research article presents a novel approach to nonlinear optical signal processing (NOSP) using parity-time (PT) symmetry in microresonator systems. The key idea is to enhance light intensity and enable high-speed operation by leveraging PT symmetry to overcome the bandwidth-efficiency limit of conventional single resonator systems. The design utilizes a PT symmetry broken regime for a narrow-linewidth pump wave and near-exceptional point operation for broadband signal and idler waves, resulting in a NOSP system with two orders of magnitude improvement in efficiency compared to a single resonator. The system is implemented using a highly nonlinear AlGaAs-on-Insulator platform, achieving NOSP at a data rate approaching 40 Gbit/s with a record low pump power of 1 mW. The device features a small footprint (about 0.01 mm²) and a broad wavelength conversion bandwidth (>170 nm), making it suitable for optical communication networks and classical or quantum computation. The combination of PT symmetry and NOSP may also open up opportunities for amplification, detection, and sensing, where response speed and efficiency are equally important. The study demonstrates that the PT symmetry-enabled linewidth manipulation allows for high-speed FWM processes with enhanced conversion efficiency. The synthetic linewidth formulation shows that the synthetic linewidth is determined by the real and imaginary parts of the eigenvalues of the coupled system. The experimental results validate the theoretical predictions, showing that the conversion efficiency is significantly improved by the PT symmetry-based design. The system outperforms existing cavity-based solutions in terms of power consumption per bit, with a power consumption of 26 fJ/bit, which is comparable to the best results achieved for waveguide devices. The study also compares the performance of the proposed system with state-of-the-art all-optical wavelength conversion experiments, showing that the PT symmetry design outperforms existing solutions in terms of power consumption per bit. The results demonstrate the potential of PT symmetry in enabling ultra-efficient NOSP systems with high-speed, high-capacity optical communications.This research article presents a novel approach to nonlinear optical signal processing (NOSP) using parity-time (PT) symmetry in microresonator systems. The key idea is to enhance light intensity and enable high-speed operation by leveraging PT symmetry to overcome the bandwidth-efficiency limit of conventional single resonator systems. The design utilizes a PT symmetry broken regime for a narrow-linewidth pump wave and near-exceptional point operation for broadband signal and idler waves, resulting in a NOSP system with two orders of magnitude improvement in efficiency compared to a single resonator. The system is implemented using a highly nonlinear AlGaAs-on-Insulator platform, achieving NOSP at a data rate approaching 40 Gbit/s with a record low pump power of 1 mW. The device features a small footprint (about 0.01 mm²) and a broad wavelength conversion bandwidth (>170 nm), making it suitable for optical communication networks and classical or quantum computation. The combination of PT symmetry and NOSP may also open up opportunities for amplification, detection, and sensing, where response speed and efficiency are equally important. The study demonstrates that the PT symmetry-enabled linewidth manipulation allows for high-speed FWM processes with enhanced conversion efficiency. The synthetic linewidth formulation shows that the synthetic linewidth is determined by the real and imaginary parts of the eigenvalues of the coupled system. The experimental results validate the theoretical predictions, showing that the conversion efficiency is significantly improved by the PT symmetry-based design. The system outperforms existing cavity-based solutions in terms of power consumption per bit, with a power consumption of 26 fJ/bit, which is comparable to the best results achieved for waveguide devices. The study also compares the performance of the proposed system with state-of-the-art all-optical wavelength conversion experiments, showing that the PT symmetry design outperforms existing solutions in terms of power consumption per bit. The results demonstrate the potential of PT symmetry in enabling ultra-efficient NOSP systems with high-speed, high-capacity optical communications.