Design of a single all-silicon ring resonator with a 150 nm free spectral range and a 100 nm tuning range around 1550 nm

We present a novel and simple method to obtain an ultrawide free spectral range(FSR) silicon ring resonator together with a tuning range covering the entire spectrum from 1500 to 1600 nm. A ring resonator with a large FSR together with a high Q factor, high tuning efficiency, and low fabrication cost and complexity is desired for many applications. In this paper, we introduce a novel way to make such a ring resonator, which takes advantage of the well-known resonance-splitting phenomenon. It is a single ring resonator with an FSR of more than 150 nm around 1550 nm and which has an easy thermo-optic tunability that can produce a tuning range around 90 nm or even more. Moreover, the device is simple to implement and can be fabricated in standard complementary metal-oxide semiconductor technology without requiring any kind of complicated processing or extra materials.The potential applications include single mode laser cavities, wavelength division multiplexing filters,(de)multiplexers, optical sensors, and integrated reflectors.