  We investigated two pion condensed phases in the frame of the two flavor
Nambu--Jona-Lasinio model at finite baryon density: the homogeneous and
isotropic Sarma phase and inhomogeneous and anisotropic
Larkin-Ovchinnikov-Fudde-Ferrell(LOFF) phase. At small isospin chemical
potential $\mu_I$, the Sarma state is free from the Sarma instability and
magnetic instability due to the strong coupling and large enough effective
quark mass. At large $\mu_I$, while the Sarma instability can be cured via
fixing baryon density $n_B$ to be nonzero, its magnetic instability implies
that the LOFF state is more favored than the Sarma state. In the intermediate
$\mu_I$ region, the stable ground state is the Sarma state at higher $n_B$ and
LOFF state at lower $n_B$.
