In this paper, a model of photonic crystal temperature sensor based on crystal microcavity in a straight photonic crystal waveguide is proposed. The transmission characteristics of light in the sensor under different temperatures are simulated by using finite-difference time-domain (FDTD) method. The thermal expansion and thermal-optic effects of silicon are taken into account. The results show that the resonant wavelength of microcavity increases linearly as the temperature rising. The waveleng...