Speaker
Description
Quantum imaging is an emerging field that leverages the principles of quantum mechanics to achieve imaging capabilities beyond classical limits. By exploiting entangled photon, quantum imaging techniques enable enhanced resolution, improved sensitivity, and novel imaging modalities such as super-resolution, ghost imaging, sub-shot-noise imaging. These approaches hold significant promise for applications in biomedical imaging, remote sensing, and optical metrology.
In this context, Single-Photon Avalanche Diode (SPAD) arrays in CMOS technology play a crucial role in the advancement of quantum imaging technologies. These arrays integrate multiple highly sensitive photodetectors capable of detecting individual photons. Thanks to custom in-pixel electronics, they can perform various operations such as photon time-stamping (with a precision in the order of hundreds of picoseconds), photon counting, time-gating and others. Combined with their capabilities for high-speed image acquisition, photon-number resolving, and spatially resolved measurements, SPAD arrays are ideal for quantum imaging experiments.
Two SPAD arrays designed in 110 nm CIS FSI technology will be presented in this work, each designed for different quantum imaging applications. The first is a multi-purpose 224×272 SPAD array with a pixel pitch of 30 µm and a fill-factor of 12.9%, featuring reconfigurable in-pixel logic. This allows the SPAD array to adapt to different quantum imaging experiments , performing photon timestamping with an in-pixel Time-to-Digital converter with a timing resolution of 180 ps, photon counting up to 127 events per pixel, and other functionalities. These capabilities make it particularly suitable for super-resolution imaging.
The second 472×456 SPAD array is specifically designed for quantum ghost imaging, exploiting entangled photon pairs properties to reconstruct high-quality images in the infrared portion of the spectrum domain. A 17 µm pixel pitch with up to 31% fill-factor implements an in-pixel backward-looking temporal correlation logic to spatially resolve entangled photons in a ghost imaging setup. Time correlation is performed between the photon and an external trigger directly at pixel level, by employing an asynchronous delay mechanism combined with a tunable time correlation window . The SPAD array allows tuning of the pixel’s correlation window width and delay, ranging from 2 ns to 27 ns and from 5 ns to 40 ns, respectively. An integrated address-based event readout circuit enables reading out only the pixels that record a correlation, significantly reducing power consumption and overall acquisition time for ghost imaging by more than an order of magnitude compared to conventional setups.
These developments demonstrate the versatility and potential of SPAD technology in pushing the boundaries of quantum imaging.
