Optical coherence tomography system mass-producible on a silicon photonic chip

Abstract

Miniaturized integrated optical coherence tomography (OCT) systems have the potential to unlock a wide range of both medical and industrial applications. This applies in particular to multi-channel OCT schemes, where scalability and low cost per channel are important, to endoscopic implementations with stringent size demands, and to mechanically robust units for industrial applications. We demonstrate that fully integrated OCT systems can be realized using the state-of-the-art silicon photonic device portfolio. We present two different implementations integrated on a silicon-on-insulator (SOI) photonic chip, one with an integrated reference path (OCTint) for imaging objects in distances of 5 mm to 10 mm from the chip edge, and another one with an external reference path (OCText) for use with conventional scan heads. Both OCT systems use integrated photodiodes and an external swept-frequency source. In our proof-of-concept experiments, we achieve a sensitivity of −64 dB (−53 dB for OCTint) and a dynamic range of 60 dB (53 dB for OCTint). The viability of the concept is demonstrated by imaging of biological and technical objects.

Silicon photonic integrated circuit for fast and precise dual-comb distance metrology

“…The influence of the tunable power splitter (TPS) can be seen in Light is routed by single-mode on-chip waveguides and by photonic wire bonds, the latter being fabricated by direct-write three-dimensional two-photon lithography [42][43][44]. Using the same fabrication technique, tailored free-form micro lens can be printed directly to the facet of the optical chip to collimate the light radiated to and from the chip edge [11]. .…”

“…Signal splitting and combining as well as heterodyne detection can be accomplished by the standard silicon photonic device portfolio, comprising also on-chip Germanium photodiodes. For coupling of light to and from the measurement path, chip-attached micro lenses could be used, fabricated by the same direct-write three-dimensional two-photon lithography used for photonic wire bonding [11]. Read-out and processing of electric signals is realized with standard electronic components connected through electrical wirebonds.…”

“…However, while early demonstrations of PIC for interferometric distance measurements made use of GaAs/AlGaAs and LithiumNiobate (LiNbO 3 ) as integration platform [5][6][7], there are only very few examples where large-scale silicon photonic integration has been exploited for applications in optical metrology. Using the silicon-on-insulator (SOI) platform, Laser Doppler vibrometers and optical frequency shifters have been demonstrated [8][9][10] and an optical coherence tomography system has been realized [11]. An integrated heterodyne interferometer for measurements of relative displacements with a standard deviation of 2 nm was demonstrated in [12].…”

Multiscale dispersion-state characterization of nanocomposites using optical coherence tomography

“…Major challenges in industrial applications are the stringent requirements with respect to mechanical stability and size of the OCT system. These requirements can be met by integration of interferometer and detection system on a silicon photonic chip41. We believe that OCT has the potential to fill a metrology gap in the emerging field of nanocomposite technology.…”

FDOCT imaging processor for portable OCT systems with high imaging rate

“…However, the recent trend has been toward small-scale apparatus for mobile medical applications. This has led to the development of microelectromechanical systems (MEMS) [7] and the photonic-integrated circuit (PIC) [8] technology for the FDOCT opticalmechanical front end. Thus, an FDOCT imaging scheme based on an area-and energy-efficient processor, such as field programmable gate array (FPGA) or application-specific integrated circuit (ASIC), could be of considerable practical value in the development of small-scale handheld FDOCT devices.…”