Overview of High Performance Quantum IR Imaging Devices
Olivier Gravrand , CEA-LETI (Olivier.email@example.com)
Quantum IR detection is of first importance, both for military and scientific purposes. Of course, the ability to perform long range passive imagery is very interesting for air, naval or terrestrial military applications. However, besides those military aspects, high performance thermal imagery or IR spectral analysis are also growing demands for industrial need (pharmacy, industrial control…). Moreover, the study of the atmosphere chemistry of the earth (or other planets) is also very fond of IR high performance detection, as a lot of gas absorption lines are usually contained in a spectral band from the near IR up to the very long wave IR (up to l=14.5µm for CO2). Last but not least, astronomical observatories are also very keen on high performance IR detector. Indeed, a large part of the information falling from the stars is contained between visible and middle wave IR. Therefore, a lot of effort has been put on the development of IR detectors to reach the highest performance, as it represents a strategically technology both for military, civilian and science purposes. In this frame, France has played an important role thru CEA-LETI, leading to the creation of Sofradir, now world leader in the IR detector market.
This seminar will start with a pedagogical review about quantum optical detection, and more specifically IR high performance detection issues. Indeed, the absorption of small energy photons requires the use of narrow gaps semiconductor structures, weather of bulk nature or synthetic (using advance heterostructures such as quantum wells or super lattices. The talk will therefore review the different technologies available today, different material systems (2-6 and 3-5s), and different detecting structures. Then an important issue will be introduced: the question of the noise affecting the detected photocurrent which has to be minimized to get the optimum detectivity.
The last part of this talk will be devoted to an overview of recent advances seen in France, both from public labs (LETI, ONERA, IES) and private companies (Thales, Safran, and Sofradir), from ultra fine pitch large focal plane arrays, to dual colors, high operating temperature imaging or even on-chip cooled optics. The conclusion will open on upcoming challenges the IR detection will face in the next few years.