We are studying Photonic Integrated Circuits.　　　▷Japanese

When the different bandgap energy bulk materials are grown layer by layer, if these lattice constants are not matched, misfit dislocation is occurred. On the other hand, in the growth of QW structure, the dislocation will not be occurred even if exist the lattice mismatch between well and barrier layer. By intoducing this strained QW structure, the lattice matched condition will be relaxed, and wide variety of material combination will be expected. In the strained QW structure, the valence band structure is changed from the lattice matched condition, and optical properties such as current injected gain, electric field refractive index or absorption change are improved. Furthermore, in the lattice matched QW structure, these properties are different by the optical poralization (TE, TM), but in the strained QW structure, it is possible to obtain the polarization independent operation. We have analyzed the electric field refractive index and absorption change in the strained QW structure.