LAUSR

Abstract This paper focuses on the temperature characteristics of single mode fiber-optic 3 × 3 couplers. Temperature change will result in the optical fiber parameters change, such as the core or cladding refractive index change and the length quantity expansion. This will affect the transmission property of the fiber-optic coupler, which can be characterized by power ratio error and phase difference error. It is found that the optical fiber geometrical expansion caused by temperature variation has little influence on the transmission characteristics of the coupler. The change of the refractive indexes, especially the core refractive index, which is caused by the thermal stress in the fiber due to temperature variation, has great influence on the transmission characteristics of the fiber-optic coupler.