Development of Cryo-CMOS Readout Circuits for Megapixel Arrays of Superconducting Nanowire Single Photon Detectors

We are currently developing kilopixel-scale arrays consisting of single-photon-sensitive superconducting nanowire detectors in the wavelength range of 2.8 – 11 µm that would meet the requirements for any future instruments directed towards exoplanet transit spectroscopy, for example the mid-infrared spectrometer and camera (MISC) planned for the Origins Space Telescope (APRA award 80HQTR20T0064). The excellent stability and single-photon sensitivity of these detectors would be ideal for such an application requiring data collection over the course of hundreds of transits of an exoplanet across its parent star, each of which can last several hours or longer. In addition, kilopixel and larger arrays are currently being developed for use in the UV region of the spectrum by my NIST colleague, Adam McCaughan, for future missions such as LUVOIR. One of the current drawbacks of using SNSPD arrays is the large number of coaxial readout lines that are required. While we have developed multiplexing techniques to reduce the total line count, these techniques have inherent drawbacks which reduce the dynamic range of the arrays. In other words, the maximum count rate does not scale linearly with the number of pixels in the array. Furthermore, our current multiplexing approaches do not scale in a practical manner above array sizes of 1 kilopixel. Our current 1 kilopixel arrays require 64 readout lines and 64 amplifiers. A 1 megapixel array with the same architecture would require 2048 lines and amplifiers. The power requirements for the amplifiers and complexity of routing such a large number of readout lines would be prohibitive for any future space-based applications. One potential solution to this problem is to leverage cryogenic SiGe heterojunction bipolar transistor (HBT) technology. Recently there has been a revival of interest in cryogenic CMOS circuits in the quantum computing community, for performing cold (4K and below) signal processing. Our colleagues at the University of Massachusetts Amherst have also performed some preliminary tests showing that SiGe transistors can be used to process signals from SNSPDs. These initial promising results indicate that it may be possible to interface an SNSPD array with a cryogenic SiGe circuit containing amplifiers, comparators, counters, and multiplexers. If this can be accomplished, it would greatly reduce the power requirements and system complexity of a 1 megapixel SNSPD array, effectively bringing CCD – like functionality to these arrays and making them more practical for use in both future space-based telescopes and ground-based applications. In the remainder of this proposal, we will outline a scalable path to developing SNSPD arrays with integrated SiGe readout circuits.

The goals of the Nancy Grace Roman Technology Fellowship (RTF) program in astrophysics are to provide early-career researchers the opportunity to develop the skills necessary to lead astrophysics flight instrument development projects, including suborbital investigations, in preparation to become Principal Investigators (PIs) of future NASA astrophysics missions; to develop innovative technologies for space astrophysics that have the potential to enable major scientific breakthroughs; and to foster new talents by putting early career instrument builders on a trajectory towards long-term positions.

This is a mature technology (TRL 7+) — the realistic path in is usually NASA's Technology Transfer Program: licensing an existing NASA patent, or a Space Act Agreement to use NASA facilities/expertise directly. NASA also runs a startup licensing program with no upfront fee for companies formed to commercialize a specific NASA technology.

None of these are guaranteed paths for this specific project — TechPort itself doesn't have an "apply" button. Reaching out to the contact(s) above with a specific question is usually the fastest way to find out what's actually open.