Millimeter-scale chip-based supercontinuum generation for optical coherence tomography.

Area of Science:

• Photonics
• Biomedical Imaging
• Materials Science

Background:

• Supercontinuum sources are crucial for optical coherence tomography (OCT), offering broad bandwidth for high resolution and high power for improved sensitivity.
• Current fiber-based supercontinuum systems necessitate high pump powers, optical filters, and exhibit limitations in sensitivity and depth performance.

Purpose of the Study:

• To introduce a novel supercontinuum generation platform using a silicon nitride (Si3N4) photonic chip for OCT.
• To demonstrate efficient supercontinuum generation near 1300 nm without postfiltering.
• To evaluate the performance of this platform in a spectral domain OCT system.

Main Methods:

• Fabrication of a 1-mm² Si3N4 photonic chip.
• Direct pumping of the chip to generate supercontinuum near 1300 nm.
• Integration of the chip into a spectral domain OCT system.
• Characterization of spectral bandwidth, system sensitivity, and depth performance.

Main Results:

• Efficient supercontinuum generation with a 105 nm flat 3-dB bandwidth was achieved using a 25-pJ pump pulse.
• The integrated OCT system demonstrated 105-dB sensitivity and 1.81-mm 6-dB sensitivity roll-off at 300-μW optical power.
• Successful imaging of breast tissue confirmed the platform's strong performance.

Conclusions:

• The Si3N4 photonic chip enables efficient, filter-free supercontinuum generation for OCT.
• This platform significantly enhances OCT sensitivity and depth performance.
• The developed chip holds promise for portable OCT systems and the integration of photonics in optical imaging.