A　novel　high　temperature　sensor　based　on　weakly-coupled　multicore　fiber　(MCF)　is　proposed　and　experimentally　demonstrated.　The　sensor　consists　of　a　taper　of　weakly-coupled　MCF　sandwiched　between　two　standard　single-mode　fibers　(SMF).　The　temperature　sensing　mechanism　is　investigated　theoretically　and　experimentally.　In　order　to　eliminate　the　effect　of　residual　stress　in　the　sensor　and　improve　the　high-temperature　sustainability　of　the　sensor,　the　annealing　techniques　for　the　proposed　sensor　is　also　investigated.　The　sensor　annealed　via　the　proposed　techniques　was　demonstrated　experimentally　to　be　able　to　measuring　temperatures　up　to　1000　degrees　C　with　sensitivity　of　similar　to　36.8　pm/degrees　C.　(C)　2018　Elsevier　B.V.　All　rights　reserved.