TiOx/Ti/TiOx Tri-layer Film-based Waveguide Bolometric Detector for On-Chip Si Photonic Sensors

Abstract

We experimentally demonstrate an on-chip optical power monitoring at the wavelength range of 1520-1600 nm using the waveguide bolometric detector with a TiOx/Ti/TiOx tri-layer film based on the silicon-on-insulator (SOI) platform. For the light absorption causing a heat generation, a heavily-doped (n^{+}) Si waveguide is adopted to utilize the mechanism of free-carrier absorption (FCA), and Au strip is deposited onto the n^{+} Si waveguide to further enhance the light absorption. A bolometric material of TiOx/Ti/TiOx tri-layer film is integrated for the thermal-to-electrical conversion. As a result, it exhibits the record-high temperature coefficient of resistance of -2.296 %/K with the record-high maximum sensitivity of -46.45 %/mW among waveguide bolometers. This work demonstrates the waveguide bolometric detector with the FCA effect, for the first time to our knowledge, which can be simply extended for the operation wavelength range to the molecular-fingerprint regions (2-20\ \mu \mathrm{m}) for bio and chemical sensing.