Spectral domain optical coherence tomography imaging with an integrated optics spectrometer

Area of Science:

• Photonics and Optical Engineering
• Biomedical Imaging Technology
• Materials Science for Optoelectronics

Background:

• Spectral domain optical coherence tomography (SD-OCT) requires high-performance spectrometers for detailed biological tissue imaging.
• Miniaturization of optical components is crucial for developing portable and cost-effective SD-OCT systems.
• Arrayed-waveguide gratings (AWGs) offer potential for compact spectrometer designs but require optimization for specific applications like SD-OCT.

Purpose of the Study:

• To design and fabricate a compact silicon oxynitride (SiON) arrayed-waveguide grating (AWG) spectrometer.
• To integrate the AWG spectrometer into a fiber-based spectral domain optical coherence tomography (SD-OCT) system.
• To evaluate the performance of the AWG-based SD-OCT system for biological tissue imaging.

Main Methods:

• Fabrication of a silicon oxynitride arrayed-waveguide grating (AWG) with a 3.0 cm × 2.5 cm footprint.
• Characterization of the AWG, including center wavelength (1300 nm) and free spectral range (78 nm).
• Integration of the AWG spectrometer with a fiber-based SD-OCT system and performance testing using phantoms.

Main Results:

• The fabricated AWG spectrometer achieved a compact size and operated at the desired 1300 nm center wavelength with a 78 nm free spectral range.
• OCT measurements demonstrated imaging capability up to a maximum depth of 1 mm with an axial resolution of 19 μm, matching design parameters.
• Cross-sectional imaging of a multilayered scattering phantom was successfully achieved using the integrated AWG-based SD-OCT system.

Conclusions:

• A compact and efficient silicon oxynitride AWG spectrometer was successfully designed, fabricated, and integrated into an SD-OCT system.
• The developed AWG-based SD-OCT system provides high-resolution imaging capabilities suitable for various biomedical applications.
• This work highlights the potential of AWG technology for miniaturizing spectrometers in advanced optical coherence tomography systems.