Enhanced efficiency thermo-optic phase-shifter by using multi-mode-interference device Bharat Pant, Weiwei Zhang, Denh Tran, Mehdi Banakar, Han Du, Xingzhao Yan, Callum G. Littlejohns, Graham T. Reed and David J. Thomson EPJ Web Conf., 238 (2020) 01007 Published online: 20 August 2020 DOI: 10.1051/epjconf/202023801007