High-Q and temperature stable photonic biosensor based on grating waveguides

In this work, analytical modeling and parameter evaluation of a photonic biosensor using cascaded silicon grating waveguides is illustrated. The sensor design consists of two cascaded waveguides with symmetric sidewall gratings to broaden the stop band region of the transmission spectra. In the work, the structure is first analyzed using the transfer matrix method. The parameter values are then optimized to obtain a sharper resonant peak in the center of the stop band. Notably, the resonant band of this structure provides a high Q factor (of 1.544 × 105), which significantly improves the limits of detection. The sensor has been designed to detect the presence of biomaterial material (seen corresponding to a change in refractive index) on its surface by changing the change in device resonant wavelength. In this study, the effect of temperature on the detection of such biomaterials has also been evaluated, as has the temperature sensitivity of the device which is − 0.0075 nm/°C, over a temperature range of 18–34 °C