As noninvasive biomedical imaging techniques, optical coherence tomography (OCT) and optical coherence microscopy have good application prospects in future. A swept-source imaging system based on a polarization-dependent semiconductor optical amplifier (SOA) enabled Fourier domain mode locked laser (FDML) is demonstrated, which can be used for the two imaging techniques mentioned above. The FDML with a polarization-dependent SOA generates ~32 mW output power at 45 kHz sweep rates, with a tuning range of 115 nm centered at 1326 nm. Because of the broad bandwidth and high saturation power of the polarization-dependent SOA, the laser has the advantage of simple structure. It uses only one SOA for operating with enough bandwidth and output power. Using the SOA-enabled FDML laser, an OCT system with axial resolution of ~12.9 μm, transverse spot size of 9 μm and sensitivity of 105 dB is achieved. The structure of the epidermal cells of onion can be observed by this imaging system.