Photonic contact thermometry using silicon ring resonators and tuneable laser-based spectroscopy

Abstract

Abstract Photonic sensors offer the possibility of purely optical measurement in contact thermometry. In this work, silicon-based ring resonators were used for this purpose. These can be manufactured with a high degree of reproducibility and uniformity due to the established semiconductor manufacturing process. For the precise characterisation of these photonic sensors, a measurement setup was developed which allows laser-based spectroscopy around 1550\u2009nm and stable temperature control from 5\u2009°C to 95\u2009°C. This was characterised in detail and the resulting uncertainty influences of both the measuring set-up and the data processing were quantified. The determined temperature stability at 20\u2009°C is better than 0.51\u2009mK for the typical acquisition time of 10\u2009s for a 100\u2009nm spectrum. For a measurement of >24\u2009h at 30\u2009°C a standard deviation of 2.6\u2009mK could be achieved. A hydrogen cyanide reference gas cell was used for traceable in-situ correction of the wavelength. The determined correction function has a typical uncertainty of 0.6\u2009pm. The resonance peaks of the ring resonators showed a high optical quality of 157\u2009000 in the average with a filter depth of up to 20\u2009dB in the wavelength range from 1525\u2009nm to 1565\u2009nm. When comparing different methods for the determination of the central wavelength of the resonance peaks, an uncertainty of 0.3\u2009pm could be identified. A temperature-dependent shift of the resonance peaks of approx. 72\u2009pm/K was determined. This temperature sensitivity leads together with the analysed uncertainty contributions to a repeatability of better than 10\u2009mK in the analysed temperature range from 10\u2009°C to 90\u2009°C.