We have demonstrated an InGaAlAs/InAlAs multiple quantum well phase mo
dulator integrated with a spot-size conversion structure. This modulat
or successfully operates with a low applied voltage and a small loss i
ncrease, and also has highly efficient coupling to single-mode fibers
and large misalignment tolerances compared with direct fiber butt coup
ling. These results show the feasibility and reliability of fiber modu
le assembly.