Multifactor roadmap for designing low-power-consumed micro thermoelectric thermostats in a closed-loop integrated 5G optical module

As the core components of fifth-generation (5G) communication technology, optical modules should be consistently miniaturized in size while improving their level of integration. This inevitably leads to a dramatic spike in power consumption and a consequent increase in heat flow density when operating in a confined space. To ensure a successful start-up and operation of 5G optical modules, active cooling and precise temperature control via the Peltier effect in confined space is essential yet challenging. In this work, p-type Bi_0.5Sb_1.5Te₃ and n-type Bi₂Te_2.7Se_0.3 bulk thermoelectric (TE) materials are used, and a micro thermoelectric thermostat (micro-TET) (device size, 2 × 9.3 × 1.1 mm³; leg size, 0.4 × 0.4 × 0.5 mm³; number of legs, 44) is successfully integrated into a 5G optical module with Quad Small Form Pluggable 28 interface. As a result, the internal temperature of this kind of optical module is always maintained at 45.7°C and the optical power is up to 7.4 dBm. Furthermore, a multifactor design roadmap is created based on a 3D numerical model using the ANSYS finite element method, taking into account the number of legs (N), leg width (W), leg length (L), filling atmosphere, electric contact resistance (R_ec), thermal contact resistance (R_tc), ambient temperature (T_a), and the heat generated by the laser source (Q_L). It facilitates the integrated fabrication of micro-TET, and shows the way to enhance packaging and performance under different operating conditions. According to the roadmap, the micro-TET (2 × 9.3 × 1 mm³, W = 0.3 mm, L = 0.4 mm, N = 68 legs) is fabricated and consumes only 0.89 W in cooling mode (Q_L = 0.7 W, T_a = 80°C) and 0.36 W in heating mode (T_a = 0°C) to maintain the laser temperature of 50°C. This research will hopefully be applied to other microprocessors for precise temperature control and integrated manufacturing.