The principle of tunnel regeneration is used to raise the optical output power of semiconductor lasers at lower injected current. The optical modes are analyzed through the transfer matrix method for the tunnel regeneration semiconductor laser with four optical coupled active regions. It is shown that TE3 should be the lasing mode, and there exists an optimum thickness for the inner cladding layers. Devices with inner cladding layer thickness of 0.3 μm, 0.5 μm and 0.7 μm are epitaxiallly grown by metal organic chemical vapor deposition method (MOCVD), respectively. The device with 0.5 μm inner cladding thickness exhibits the best P-I characteristics, the optical power exceeds 5 W under 2 A driving current without facet coating, and the slope efficiency reaches 2.74 W/A. The results show that the thickness of the inner cladding layers should be designed properly so that a higher optical output power can be obtained.