Photonic ring modulators with high tuning efficiency and small footprint can be formed in a hybrid material platform from a silicon bus waveguide vertically coupled to an optically active compound semiconductor (e.g., III-V) ring resonator. The performance of the modulator, e.g., in terms of the tuning efficiency and the maximum insertion loss, may be optimized by suitable levels of an applied bias voltage and a heater power of a heater optionally included in the ring modulator. The disclosed hybrid photonic ring modulators may be used, e.g., in photonic transceiver circuits with high lane count.