We experimentally demonstrate a microelectromechanically (MEMS) tunable photonic ring resonator add-drop filter, fabricated in a simple silicon-on-insulator (SOI) based process. The device uses electrostatic parallel plate actuation to perturb the evanescent field of a silicon waveguide, and achieves a 530 pm resonance wavelength tuning, i.e., more than a fourfold improvement compared to previous MEMS tunable ring resonator add-drop filters. Moreover, our device has a static power consumption below 100 nW, and a tuning rate of −62 pm∕V, i.e., the highest reported rate for electrostatic tuning of ring resonator add-drop filters. Ring resonators are key components of silicon photonics due to their small footprint and ability to filter and route narrowband signals. The rings show standing wave resonances when the optical path length of the ring waveguide is a multiple of the excitation wavelength. Thus, by changing the optical length of the ring, e.g., by perturbing the effective refractive index of the waveguide mode, one can tune the resonance wavelength. [7], and tunable lasers [8]. Most of these applications require densely packed high-Q rings that are able to add and drop down to 50 GHz channels, with wavelength tuning spanning a number of channels. Moreover, such applications require ring resonators with independent tuning, i.e., low cross-talk between adjacent devices.Ring resonators tuned by free-carrier injection have achieved high-speed tuning [9]. However, free-carrier absorption results in high optical loss and short wavelength shift, which limits their usefulness for add-drop applications. Thermo-optic tuning of ring resonators has shown large wavelength shift with low optical loss [10], but high power consumption and thermal cross-talk between neighboring devices hamper its applicability in densely integrated optical interconnects [11]. Integration of electro-optic materials with low static power dissipation have so far shown low tuning effects, high driving voltages, and optical interference due to fabrication complexity [12]. Table 1 summarizes reported performance of tunable ring resonator add-drop filters.MEMS tunable ring resonators are good candidates for wavelength selection in optical networks due to their low static power dissipation and high optical Q. Such filters have already shown low-power wavelength tuning [14], but since the tuning mechanism was based on deflecting a deposited cantilever on Fig. 1. Most applications of tunable add-drop filters require a large number of densely packed devices with low cross-talk. Here, we demonstrate a low-power MEMS tunable add-drop filter fabricated by a simple SOI-based process. Parallel plate actuation of a free-standing cantilever that contains the ring resonator waveguide changes the waveguide geometry. This affects the effective refractive index of the resonant optical mode, resulting in a shift of resonance wavelength.