Figure 1: No QW left outside the cavity after the selective wet etching.

(a) Carefully breaking the sample after the wet etching, we observe that dislocation between the upper and lower InP cladding appears only outside the cavity, which proves that QW remains only inside the cavity region. (b) Mechanically removing the upper InP cladding, a broken piece of InP remains attached to the corresponding QW area that is left after the wet etching.