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 $111\mathrm{nm}$ centered at $1329\mathrm{nm}$ , coherence length of $5.5\mathrm{mm}$ , and total average output power of $131\mathrm{mW}$ at $43\mathrm{kHz}$ sweeping rate. Multichannel simultaneous OCT imaging at an equivalent A-scan rate of $258\mathrm{kHz}$ is demonstrated.