Frequency-comb generation based on electro-optic phase-code mode-locking for circular-ranging OCT

A source for providing electromagnetic radiation within a particular spectral range, comprising:

• a ring-shaped optical resonator for circulating a plurality of wavelength bands including:
• a first optical phase modulator,
• a first chromatic dispersion device,
• a second optical phase modulator,
• a multi-line spectral domain filter,
• a second chromatic dispersion device, and
• an optical amplifier;
• a controller coupled to the first optical phase modulator and the second optical phase modulator which is configured to drive the first optical phase modulator with a first waveform and the second optical phase modulator with a second waveform,
• the first chromatic dispersion device being configured between the first optical phase modulator and the second optical phase modulator to provide chromatic dispersion so as to subject each of the plurality of wavelength bands to a respective plurality of different time delays,
• the first optical phase modulator and the second optical phase modulator being configured to create spectral broadening by the first optical phase modulator of each of the plurality of wavelength bands and spectral recovery by the second optical phase modulator of a particular wavelength band of the plurality of wavelength bands by modulating a first phase using the first optical phase modulator driven by the first waveform and, after a particular time delay, modulating a second phase using the second optical phase modulator driven by the second waveform comprising an inverse of the first waveform,
• the particular time delay being determined so as to create spectral recovery for the particular wavelength band of the plurality of wavelength bands,
• the multi-line spectral domain filter being configured to provide multi-line spectral filtering with narrow bandwidths in order to induce power loss for each of the plurality of wavelength bands except for the particular wavelength band,
• the second chromatic dispersion device being configured to provide chromatic dispersion compensation to an output of the multi-line spectral domain filter in order to compensate a group delay dispersion within the ring-shaped optical resonator and match a roundtrip frequency for each of the plurality of wavelength bands, and
• the first and second waveforms being configured to create a periodic phase modulation for recovery of the plurality of wavelength bands at a frequency that is an integer multiple of a roundtrip frequency of the ring-shaped optical resonator.