Impact of thermal and refractive index tuning on the bandgap and band-edges of a silicon photonic crystal waveguide with sensing applications

This paper proposes the design of a silicon photonic crystal waveguide with a hexagonal lattice structure. In the proposed structure, the effect of temperature variation on the photonic band edges has been studied. Structural design parameters have been optimized for TM and TE modes to obtain bandgap in the optical communication window of 1550 nm at room temperature. The variation in the refractive index of the silicon slab with temperature ranging from 300 K–400 K has been considered and the tuning of photonic band-edge wavelength with thermo-optic effect is presented. The band edges are found to shift linearly with changes in temperature for both TE and TM modes. A sensitivity of 0.0595 nm/K for TM mode and 0.0587 nm/K for TE mode has been observed and thus the proposed structure can be used as a temperature sensor. This paper also presents the tuning of the bandgap and band-edges by changing the refractive index of the holes in the proposed structure. The wavelength of the band-edges is found to increase whereas the bandgap is found to decrease on increasing the refractive index of the holes for both TM and TE modes. It is observed that the proposed structure offers a refractive index sensitivity of 10.105 nm/RIU for TM mode and 34.953 nm/RIU for TE mode and thus can be used as a refractive index sensor. • Thermo-optic effect in silicon used to tune the band-edges of the photonic crystal waveguide with temperature. • A high sensitivity of the proposed structure indicating temperature sensing applications. • Bandgap and band-edges of the structure tuned by variation in refractive index of the holes.