We employed a 1700nm swept-source PS-OCT to image fibrous collagen in fibrotic lung tissue through phase retardation images. To confirm the fibrous collagen, we utilized SHG signal imaging from two-photon microscope. The SHG signal was generated specifically in fibrous collagen tissue. In conclusion, the comparison between the phase retardation images and SHG images demonstrated that the PS-OCT system can be useful in detecting pulmonary fibrosis.