Laser swept source with controlled mode locking for OCT medical imaging

An optical coherence imaging method, comprising:

• providing a laser swept source having a laser cavity that is less than a meter long and defined between a Fabry-Perot tunable filter and an output coupler at one end of a fiber, the laser swept source further comprising a semiconductor optical amplifier (SOA) chip having a gain section, and an intracavity phase modulator configured to be driven at a rate related to the round trip time of the laser cavity, wherein the phase modulator is integral with the SOA chip and configured to be driven at a harmonic of the round trip frequency of the laser cavity by a bias source different from a bias source for the gain section;
• controlling a swept mode-locked operation of the laser swept source by actively modulating cavity gain by applying a bias current to the gain section synchronized with a round trip time of the laser cavity to produce one laser pulse per round trip, and generating a swept optical signal;
• transmitting the swept optical signal to an interferometer having a reference arm and a sample arm, in which a sample is located;
• combining the swept optical signal returning from the sample arm and the reference arm to generate an interference signal;
• detecting the interference signal;
• and
• generating image information of the sample from the detected interference signal.