"Raman-pumped Fourier-domain mode-locked laser: analysis of operation and application for optical coherence tomography"
Thomas Klein, Wolfgang Wieser, Benjamin R. Biedermann, Christoph M. Eigenwillig, Gesa Palte, Robert Huber
Optics Letters 33, 2815-2817 (2008)
Abstract: We demonstrate a Raman-pumped Fourier-domain mode-locked (FDML) fiber laser and optical coherence
tomography imaging with this source. The wavelength sweep range of only 30 nm centered around 1550 nm
results in limited axial resolution, hence a nonbiological sample is imaged. An output power of 1.9 mW was
achieved at a sweep rate of 66 kHz and a maximum ranging depth of 2.5 cm. Roll-off characteristics are found to be similar to FDML lasers with semiconductor optical amplifiers as gain media. The application of Raman gain also enables unperturbed cavity ring-down experiments in FDML lasers for the first time, providing direct access to the photon lifetime in the laser cavity. Good agreement with nonswept cw operation is proof of the stationary operation of FDML lasers.