Picosecond pulses from a Fourier domain mode locked (FDML) laser

Fourier domain mode locked lasers (FDML)[1] are very rapidly wavelength swept lasers where a narrowband optical bandpass filter is driven synchronously to the round-trip time of light in the resonator providing narrow instantaneous linewidths (~50pm) over a large wavelength sweep range (~100nm) at sweep repetition rates of ~20kHz-5MHz[2]. In biomedical imaging, FDML lasers currently are the light sources of choice for ultrahigh speed optical coherence tomography (OCT) with multi-megahertz A-scan rates[2].