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Optoelectronic system based on photonic integrated circuits to miniaturize spectral domain OCT
(2023)
We present a miniaturized optical coherence tomography (OCT) setup based on photonic integrated circuits (PIC) for the 850 nm range. We designed a 512-channel arrayed waveguide grating (AWG) on a PIC for spectral domain OCT (SD-OCT) that is co-integrated with PIN-photodiodes and analog-to-digital-converters on one single chip. This image sensor is combined with all the necessary electronics to act as a camera. It is integrated into a fiber-based OCT system, achieving a sensitivity of >80dB and various samples are imaged. This optoelectronic system will allow building small and cost-effective OCT systems to monitor retinal diseases.
We present the technological verification of a size-optimized 160-channel, 50-GHz silicon nitride-based AWG-spectrometer. The spectrometer was designed for TM-polarized light with a central wavelength of 850 nm applying our proprietary “AWG-Parameters” tool. For the simulations of AWG layout, the WDM PHASAR photonics tool from Optiwave was used. The simulated results show satisfying optical properties of the designed AWG-spectrometer. However, the high-channel count causes a large AWG size with standard design approaches. To solve this problem we designed a special taper enabling the reduction of AWG structure by about 15% while keeping the same optical properties. The AWG design was fabricated and the measured spectra not only confirm the proposed size-reduction but also the improvement of optical properties of the size-optimized AWG.