In this paper, a temperature sensor has demonstrated using the opto-thermal disk-resonator (OTDR). The sensor is designed based on Whispering Gallery Mode (WGM) principle. The OTDR is a novel technique to integrate thermal science and optical technology. Optical resonances of Transverse Electric (TE) wave propagations in dielectric micro-disk resonator have been developed based on asymptotic approach. The developed expressions for size parameter for TE wave is very simple and can be used to characterize the resonances in dielectric micro-disk resonator. Asymptotic expression has applied to predict the resonance frequency at different temperatures. The sensor performance has been studied by using finite element simulation and found encouraging result for temperature sensing. Theoretical analysis shows that present study will lead to development of novel OTDR sensors for MEMS and nano applications.