We report a high-power wavelength-swept laser source for multichannel optical coherence tomography (OCT) imaging. Wavelength tuning is performed by a compact telescope-less polygon-based filter in Littman arrangement. High output power is achieved by incorporating two serial semiconductor optical amplifiers in the laser cavity in Fourier domain mode-locked configuration. The measured wavelength tuning range of the laser is 111 nm centered at 1329 nm, coherence length of 5.5 mm, and total average output power of 131 mW at 43 kHz sweeping rate. Multichannel simultaneous OCT imaging at an equivalent A-scan rate of 258 kHz is demonstrated.