High-Speed Optical Interconnect for Cryogenically Cooled Focal Plane Arrays
Abstract
Military imaging requirements demand continuous improvements in Focal Plane Array (FPA) resolution, size, sensitivity and frame rate, driving the need for high-speed interconnects between the FPA, located inside a cryogenic Dewar, to the processing electronics in the ambient environment. Significant advances in operational bandwidth are needed to support future high definition (HD) and high-pixel count formats, in addition to faster frame rate requirements (up to a kHz or more). Therefore, interconnect speeds of many tens of Gbps will soon be required with future demand growing to possibly many hundreds of Gbps. Currently, electrical interconnects, which are limited to data rates of approximately 2.5 Gbps, are used to read-out FPAs. As the number of high-speed metallic interconnect data lines increases, passive thermal heat loading between the cold FPA and the warm Dewar increases, degrading the cryostat cooling efficiency. Optical interconnects, based on either Free-Space Optical (FSO) or fiber-optic link technology, provide a unique solution by significantly minimizing passive heat loading, while simultaneously providing high-speed and scalable interconnects, especially when utilizing wavelength division multiplexing (WDM). Recently, Freedom Photonics LLC and the University of California Santa Barbara, have developed a high-speed optical interconnect for cryogenically cooled FPAs based on a micro-ring resonator electro-optic modulator (EOM) implemented in a silicon(Si) photonics platform, that is WDM scalable for applications requiring >40 Gbps operation. The modulator device, fabricated through the American Institute for Manufacturing (AIM) Photonics program, demonstrated 1E-10 bit error rate (BER) at 10 Gbps and 300 K operation. Subsequent device design iterations have targeted larger bandwidths and mitigation of carrier-freeze out under cryogenic operation utilizing highly doped regions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 25, 2019
- Accession Number
- AD1075373
Entities
People
- Aaron Maharry
- Clint Schow
- Daniel Renner
- Mario Dumont
- Steven Estrella
- Takako Hirokawa