Picosecond pulses from an FDML laser

The recently developed Fourier Domain Mode Locked lasers (FDML) [1] are very rapidly wavelength swept light sources, where a narrowband optical bandpass filter is driven resonantly to the round-trip time of light in the resonator, providing small instantaneous linewidths (∼50pm) over a large wavelength sweep range (∼100nm) at sweep repetition rates of ∼20kHz–5MHz [2]. In biomedical imaging, FDML lasers represent the light sources of choice for high speed optical coherence tomography (OCT) with multi-megahertz A-scan rates [2].