Characterization of surface- and defect-state absorption in silicon waveguides and microring resonators in 1310-1550nm

• Published in: 2016 Progress in Electromagnetic Research Symposium (PIERS) p. 2403
• Main Authors: Yu Li, Poon, Andrew W.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.08.2016
• Subjects: Ion implantation; Optical resonators; Optical surface waves; Optical waveguides; Silicon; Surface waves
• DOI: 10.1109/PIERS.2016.7734987

We report our recent progress in characterizing sub-bandgap surface-state absorption (SSA) and defect-state absorption (DSA) in foundry-fabricated silicon waveguides and microring resonators in 1310-1550nm wavelengths. While SSA is widely regarded as a fundamental linear absorption loss due to surfaces and interfaces for silicon waveguides and microring resonators, our previous work has shown that one can leverage the weak SSA-induced photo-responsivity for actively monitoring and stabilizing silicon microring resonators against dynamic environmental conditions. In order to enhance the responsivity for active stabilization, we can use ion implantation to locally enhance the density of defect states in the bulk of silicon waveguides and microring resonators for attaining better spatial overlap between the defects and the optical modes. In this talk, we will review our recent experimental progress using a silicon microring embedded with an air-clad pin diode, with or without ion implantation in the diode intrinsic region. The diode with ion implantation allows us to characterize DSA, while the diode without ion implantation allows us to characterize SSA. We measure the responsivities at a microring resonance wavelength upon a −1V bias. For SSA characterization, our current experiments reveal a waveguide responsivity of ∼ 3.1 ± 0.5mA/W/mm in 1550nm wavelengths among 15 microrings fabricated from a single fabrication run. For DSA characterization, our preliminary experiments using Ar-ion implantation reveals a waveguide responsivity of ∼ 66mA/W/mm in 1550nm wavelengths, which is ∼ 19 times larger than the SSA-induced responsivity of the same diode before implantation. Further experiments and numerical modeling for silicon SSA- and DSA-induced responsivities in 1310/1550nm wavelengths under different surface conditions and ion implantations are on-going and will be discussed at the conference.