Decreasing the Size of a Spectral Domain Optical Coherence Tomography System With Cascaded Arrayed Waveguide Gratings in a Photonic Integrated Circuit

This paper describes a proof-of-concept of a miniaturized spectral-domain optical coherence tomography system, based on photonic integrated circuit (PIC) technology. The integrated optics 512-channel spectrometer consists of cascaded arrayed waveguide gratings (AWG) with the output waveguides directly attached to a CCD detector. The spectrometer has a center wavelength of 850 nm and a spectral sampling interval of 0.22 nm. The PIC has a footprint of 2.0 × 2.7 cm
²
. The wavelength response of the cascaded AWG spectrometer is calibrated with a tunable laser. Free space OCT measurements are done with a mirror as sample. The signal-to-noise ratio is ~77 dB. Due to the ~three times larger optical bandwidth incident on each CCD pixel, the sensitivity rolls off faster in depth than based on the spectral sampling interval. The axial resolution of the OCT system is determined at 5.9 ± 0.4 μm. We demonstrate the imaging capabilities of this PIC based system by imaging a multilayered phantom. Our results show the basis for the development of a handheld OCT system based on PIC technology, thereby facilitating the development of more applications of OCT.