Researchers at the University of Illinois Urbana-Champaign have demonstrated that cryogenic vertical-cavity surface-emitting lasers (cryo-VCSELs) could provide a more energy-efficient method of transmitting data from infrared imaging systems while reducing thermal load.
The findings, published in IEEE Photonics Technology Letters recently, address a growing challenge facing advanced infrared focal plane arrays (FPAs), which increasingly require data transmission rates exceeding 100 gigabits per second as sensor resolution and imaging speeds improve.
Conventional electrical interconnects rely on copper links that can transfer heat into cryogenic imaging systems, increasing noise levels, cooling requirements and power consumption.
The researchers investigated optical interconnects based on cryogenic VCSELs as an alternative.
“Optical interconnects, which use lasers to transmit data through optical fibers, can reduce heat transfer while maintaining high data rates,” explained study author Liu.
The team evaluated the devices at cryogenic temperatures of 77 Kelvin and 120 Kelvin. According to the study, the cryo-VCSELs achieved a 3-decibel modulation bandwidth of more than 50 GHz while operating at bias currents below 4 mA.
The devices supported 112 Gb/s per lane PAM-4 data transmission with low signal distortion and demonstrated operation at speeds of up to 138 Gb/s per lane. The reported TDECQ values were 3.42 dB at 77 K and 4.15 dB at 120 K, meeting IEEE requirements for short-reach multimode optical communication.
The researchers also estimated energy consumption at approximately 68 femtojoules per bit at 77 K and 60 femtojoules per bit at 120 K, indicating efficient operation at cryogenic temperatures.
“These results demonstrate that cryo-VCSEL optical links can be a promising and cost-effective solution to meet the high-speed data communication demands of FPAs,” Liu added.
The researchers conclude that cryo-VCSEL-based optical interconnects could provide a practical and cost-effective approach for high-speed communications in cryogenic infrared focal plane arrays and other systems requiring low-temperature operation.
