(Invited) Electrodeposited Micro Thermoelectric Module Design for Hybrid Semiconductor Laser Cooling on a Silicon Photonics Platform

With the promise of highly integrated, high performance optoelectronic devices for communication applications, silicon photonics has emerged as a scalable solution to meet the demands for increased bandwidth in communication networks. An ultimate vision for silicon photonics realizes the integration of both electronic and photonic functionality in optoelectronic devices. However, while such level of integration has appeal, it introduces new thermal challenges alongside already existing ones; all of which have to be dealt with against the backdrop of the need for more compact, higher performance and energy efficient thermal solutions. In particular, the performance of active photonic devices, such as semiconductor lasers and optical amplifiers, are thermally sensitive; being required to operate at temperatures significantly lower than their electronic counterparts and often below the ambient temperature found in equipment racks.  In traditional non-integrated optoelectronic packages, this thermal requirement has been dealt with by isolating temperature sensitive devices and cooling them using centimeter-scale thermoelectric modules. However, this solution is poorly suited to integrated optoelectronic devices sharing the same substrate and limits the minimum system size.

An alternative approach is to integrate thermoelectric temperature control at the device level to simultaneously provide targeted cooling for individual temperature sensitive devices and reduce the footprint of the thermal solution to enable full optoelectronic integration. Here we present the design of a micro thermoelectric cooler (μTEC) integrated around a hybrid laser, i.e., direct band-gap III-V material wafer-bonded to a silicon-on-insulator substrate, where the key fabrication step is the electrodeposition of p-doped (Bi_1-xSb_x)₂Te₃ and n-doped Bi₂(Te_xSe_1-x)₃. We outline the processing requirements needed to ensure backend compatibility with silicon photonics fabrication. Starting with baseline experimental performance data for our hybrid laser technology and thermoelectric properties reported in the literature, we develop a multiphysics numerical model of the hybrid laser with integrated μTEC. We then assess our design in terms of system-level relevant operating temperatures and laser performance requirements. Our results suggest that electrodeposited μTECs can meet the thermal requirements of active photonics devices in silicon photonics under realistic operating conditions. We conclude by highlighting performance enhancements to be gained by improving electrodeposited material processing beyond the state-of-the-art.