In the proposed reconfigurable three-channel optical power splitter, the output power in each port is thermally tunable, providing three reconfigurable functions: $1\xd71$, $1\xd72$, and $1\xd73$ optical power splitter. To achieve these functions, the desired phase shifts of the I–IV thermal tuning areas are easily calculated based on Eqs. (4) and (5): Display Formula
$(\varphi I,\varphi II,\varphi III,\varphi IV)1\xd71\u2009\u2009MMI=(2/3\pi ,2/3\pi ,0,0),(\varphi I,\varphi II,\varphi III,\varphi IV)1\xd72\u2009\u2009MMI=(0,5/12\pi ,1/4\pi ,0),(\varphi I,\varphi II,\varphi III,\varphi IV)1\xd73\u2009\u2009MMI=(0,0,0,0).$(6)