Charge–Discharge Digital/Analog Microring Modulator With No Intrinsic Speed Limitation

Coupling modulation in microring resonators substantiates a compact and high bandwidth silicon photonics modulation scheme. In this letter, we present large-signal analysis elucidating that the main drawback of this scheme is the cavity energy decay during analog and digital modulation. Then, we propose a solution, charge-discharge configuration, having two optical inputs to compensate for the power drainage from the ring. This new modulator exhibits RF-bandwidth and extinction ratio not limited by Q-factor with virtually unlimited modulation bandwidth. We emphasize an Orthogonal Frequency-Division Multiplexing (OFDM) modulation format at 50 GHz and show it is feasible on a silicon photonics platform.