An InP optical 90?hybrid based on a ×4 MMI coupler with a deep ridged waveguide is designed and fabricated. The working principle of the 90?hybrid is systematically introduced. Three-dimensional beam ropagation method (3D BPM) is used to optimize the structure parameters of the 90?hybrid. The designed compact structure is demonatrated to have a low excess loss less than-0.15 dB, a high common mode rejection ratio better than 40 dB, and a low relative phase deviation less than ±2.5?. The designed hybrid is manufactured on a sandwitched structure deposited on an InP substrate. The measured results show that the common mode rejection ratios are larger than 20 dB in a range from 1520 nm to 1580 nm. The phase deviations are less than ±5? in a range from 1545 nm to 1560 nm and less than ±7? across the C band. The designed 90?optical hybrid is suitable well for realizing miniaturization, high-properties, and high bandwidth of coherent receiver.