Dual-parameter optical sensor with cascaded ring resonators for simultaneous refractive index and temperature sensing

•A cascaded period structure grating ring resonator of eliminating external interference is proposed.•The sensitivities of refractive index and temperature are 0 and −67.3 pm/K in the Ring_1.•The sensitivities of refractive index and temperature are 361.4 nm/RIU and 18.3 pm/K in the Ring_2.•The maximum deviation values of the Ring_1 and Ring_2 resonators are about 0.149% and 0.230%.•The proposed structure is a promising dual-parameter and anti-interference sensor.