Integrated Thermoelectric Cooling for Silicon Photonics

Abstract

Integrated silicon photonics has emerged as a scalable optoelectronic platform to meet the demands for increased bandwidth in communication networks. However, integration introduces new thermal challenges to achieving the required system performance. Here we present the design of a micro thermoelectric temperature controller integrated around a III-V-on-silicon hybrid waveguide. We briefly outline the thermal requirements to ensure suitable hybrid laser performance for a long reach optical communication application on a silicon photonics platform, namely an active region temperature of ≤ 54 • C. We then develop a multiphysics numerical model of a micro thermoelectric temperature controller integrated around the waveguide and assess our design in terms of ambient operating temperatures of 80 • C relevant for an integrated optoelectronic system. Our simulations indicate that state-ofthe-art electrodeposited bismuth telluride can achieve the required refrigeration with suitable system design optimization. Despite characteristically low cooling efficiencies compared to a macroscopic thermoelectric module solution, considering overall system energy consumption shows that targeted refrigeration using our integrated thermoelectric design can be beneficial when cooling up to ∼20% of the overall system thermal load. Our results show the promise of integrated thermoelectric temperature control to meet the thermal requirements for integrated silicon photonics under realistic operating conditions. © The Author 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.1,2 However, while such level of integration has the potential to significantly reduce packaging costs and improve optoelectronic system efficiency, 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 temperature sensitive. Moreover, these active photonic devices are required to operate at temperatures significantly lower than their electronic counterparts and often below standards-defined operating ambient temperatures required for telecommunications equipment. 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 (TEC). However, this solution is poorly suited to integrated optoelectronic devices sharing the same substrate and will limit the minimum system size as industry evolves toward an optoelectronic system-in-package archi...

Micro thermoelectric devices: From principles to innovative applications

“…An attractive design of thermally integrated chip photonics was presented by R. Enright et al [111] As shown in Fig. 10(d), it illustrates the architecture of the thermoelectric temperature controller and its integration conceptually into an integrated photonics system.…”

Optical Technology for NFV Converged Networks

“…This method is not optimal from the point of view of power consumption and packaging, especially in the perspective of obtaining a higher integration level. A different approach that promises a more efficient temperature control and a higher potential for dense integration consists in the use of micro-TECs [40,41]. These are micron-size coolers that are placed in proximity of the hot-spots, minimizing the parasitic thermal resistance between the heat source and the thermoelectric cold junction.…”

Design Guidelines for Micro‐Thermoelectric Devices by Finite Element Analysis

“…Performance analysis of macro and micro TECs by numerical approaches, both analytical and using finite element analysis (FEA), have been previously reported, including the particular case of electrochemically fabricated integrated µTECs . However little attention has been paid to study the realistic scenarios, where microfabrication processes generally impact the materials' properties (i.e., Seebeck coefficient α, electrical resistivity ρ, and thermal conductivity κ) resulting in deviations from their bulk values .…”