Abstract
In this article, we experimentally demonstrate an on-chip optical power monitoring at the near-infrared spectral region (1520–1600 nm) using the waveguide bolometric detector with a TiO<sub><i>x</i></sub>/Ti/TiO<sub><i>x</i></sub> tri-layer film based on the silicon-on-insulator (SOI) platform. For the incident light absorption causing a heat generation, a heavily doped (<inline-formula> <tex-math notation="LaTeX">${n}^{+}$ </tex-math></inline-formula>) Si waveguide is introduced to utilize the mechanism of free-carrier absorption (FCA), and a metal (Au) strip is deposited onto the <inline-formula> <tex-math notation="LaTeX">${n}^{+}$ </tex-math></inline-formula> Si waveguide to further enhance the light absorption. A bolometric material of TiO<sub><i>x</i></sub>/Ti/TiO<sub><i>x</i></sub> tri-layer film is integrated for the thermal-to-electrical conversion. As a result, it exhibits superior performances, which are the temperature coefficient of resistance (TCR) of −2.296%/K and the maximum sensitivity of −46.45%/mW with a low wavelength-dependency. In addition, a rapid response time is obtained with the rise/fall time of <inline-formula> <tex-math notation="LaTeX">$24.6 ~\mu \text{s}/29.8 ~\mu \text{s}$ </tex-math></inline-formula>, which is enough for a variety of optical sensing applications. This work demonstrates the waveguide-based bolometric photodetection using the FCA effect, for the first time to our knowledge, which can also be simply extended for the operation wavelength range to the mid-infrared (MIR) spectral region for bio/chemical sensing applications.
Published Version
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