Multiscale design of cryogenic thermoelectric coolers for infrared detectors

Cryogenic thermoelectric cooling of infrared (IR) detectors remains challenging because the performance of multistage coolers is governed by strongly coupled electrical, thermal, and geometrical parameters. Here, we present a multiscale design methodology combining the optimal control method (OCM), which determines the optimal stage configuration, operating current, and thermoelectric leg geometry, with finite-element modeling (FEM), which quantifies parasitic heat influx and refines the module design under realistic operating conditions. The methodology was demonstrated through the design of an eight-stage thermoelectric cooler for a 10 mW infrared detector operating at 150 K. The optimized architecture consists of a six-stage Bi 2 Te 3 -based high-temperature section and a two-stage hybrid Bi 0.5 Sb 1.5 Te 3 /Bi 0.91 Sb 0.09 ultra-low-temperature section. Compared with a conventional Bi 2 Te 3 design, the proposed architecture reduces the required number of thermoelectric unicouples by approximately 12 % (869 vs. 977) and decreases the electrical power consumption by approximately 12 % while maintaining the required cooling performance. FEM simulations further showed that parasitic heat influx increases the electrical power consumption of the ultra-low-temperature stage by approximately 34 %, demonstrating that these losses must be considered during module optimization. The proposed multiscale methodology enables the module architecture, geometry, and operating conditions to be determined before prototype fabrication.