Periodic waveguide structures for on-chip modulation and sensing
In this paper, we summarize the recent progress on silicon photonics modulators and sensors with an emphasize on the innovation in waveguide structure. We will introduce two types of waveguide, one-dimensional (1D) slot photonic crystal waveguide (SPCW) and subwavelength grating (SWG) waveguide. The simple geometry of 1D SPCW makes it more robust to fabrication imperfections and helps reduce its propagation loss, while still maintaining the benefit of slow light. The effective electro-optic (EO) coefficient increases to 490 pm/V. The electromagnetic (EM) wave sensor developed based on this waveguide shows a sensitivity of 1.8 V/m at 14.1 GHz, which is the most sensitive EM wave sensor that has been reported. The SWG waveguide ring resonator has a bulk sensitivity more than 400 nm/RIU, which is much higher than its strip waveguide counterpart. Furthermore, its surface sensitivity is relatively independent of the thickness of analytes accumulated on its surface. These features make it an appealing sensing platform.
