Defect solitons in triangular optical lattices

We report the existence and stability of solitons in triangular optical lattices with a defect in saturable nonlinearity. With the changes of defect intensity, defect solitons may exist in different gaps. For a positive defect, solitons only exist in the semi-infinite gap and can be stable in the low power region. For a negative defect, solitons can exist in the semi-infinite gap and in the first gap. With the increasing of the negative defect depth, solitons will be stable only in the moderate power region in the first gap, and the stable region will become more and more narrow.