A Vision for Thermally Integrated Photonics Systems

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...

Section: Numerical Implementationmentioning

confidence: 98%

“…4 This thermal architecture is complemented by integrated microfluidics offering low thermal resistance for improved system power handling and/or to allow for higher thermal management system operating temperatures. Thermally Integrated Photonics System (TIPS) conceptual architecture.…”

mentioning

confidence: 99%

Integrated Thermoelectric Cooling for Silicon Photonics

Enright¹,

Lei²,

Cunningham³

et al. 2017

“…The vision is to integrate AlN heat spreaders, μTEC and micro-fluidics (μFluidics) with optoelectronic devices in order to precisely and autonomously control individual device temperature and thus, device performance, in terms of wavelength and optical output power, to enable system-on-a-chip integration. 54 In terms of thermoelectric coolers, materials with high thermoelectric efficiency near room temperature (e.g., Bi 2 Te 3 -based composites), which can be developed directly on wafers and compatible with semiconductor fabrication process and do not require complicated and long processing time, are desirable. Electroplating of these materials directly at wafer scale is way forward in realizing this vision of μTEC in the application of thermal management of photonic devices.…”

Section: Thermally Integrated Thermoelectric Cooling For Photonicsmentioning

confidence: 99%

Scientific and Technical Challenges in Thermal Transport and Thermoelectric Materials and Devices

O’Dwyer

Chen

et al. 2017

This paper considers the state-of-the-art and open scientific and technological questions in thermoelectric materials and devices, from phonon engineering and scattering methods, to new and complex materials and their thermoelectric behavior. The paper also describes recent approaches to create structural and compositional material systems designed to enhance the thermoelectric figure of merit and power factors. We also summarize and contextualize recent advances in the use of superlattice structures and porosity or roughness to influence phonon scattering mechanisms and detail some advances in integrated thermoelectric materials for generators and coolers for thermally stable photonic devices. Controlling heat transport, dissipation and its conversion to other forms of energy are major research drivers for both materials researchers and device/product specialists alike.1,2 In parallel, nanoscale materials developments have provided insight and evidence for unusual and sometimes scalable phonon scattering phenomena to cause significant thermal conductivity suppression, often while maintaining electron conductivity in materials where electron specific heat contributions and other effects are controlled, such that relatively high thermoelectric figures of merit (ZT) can be obtained. The figure of merit Z T = S 2 σT /κ, where S = − V / T is the Seebeck coefficient ( V is the voltage difference caused by a temperature difference T ), σ is the electrical conductivity and κ is the thermal conductivity. Research and development in chip-or system-level cooling continuously provides the impetus for many of these developments, from semiconductor material cooling within a high clock-speed chip, to system level cooling of processors and data-farm thermal management.In tandem with thermal conductivity and transport control in materials and modules, is the necessity for understanding how material size, composition, structure and arrangement can alter phonon and heat transport, so that other research questions and technological advancements can be tackled. For instance, the required local (electrical) heating for phase change materials and memristors depends on thermal transport, heat dissipation and cooling to set the resistance memory or switching behavior. Annealing, sintering, and a host of other thermal treatments can influence and modify the physical properties of nanomaterial assemblies and thin films. The control and exploitation of these effects requires accurate measurement and interpretation of thermal transport to describe the important changes to composition, structure and arrangement caused at elevated temperature. There are many more cases where a more detailed understanding of heating and cooling for reasons other than power generation or thermoelectric control are important. In many cases, the experimental measurements are state-of-the-art and the modifications to the nature of the materials can often be very complex. 3 We summarize some of the * Electrochemical Society Member. z E-mail: c.odwyer@ucc.ie main a...

“…1 The -structured microthermoelectric coolers hereby encase the active component using a vertical integration. In Fig.…”

mentioning

confidence: 99%

Fabrication and Modeling of Integrated Micro-Thermoelectric Cooler by Template-Assisted Electrochemical Deposition

Garcı́a

Ramos

Mohn

et al. 2017

In this work, we report on the structured electrochemical deposition of smooth and compact 12 μm thick films of Bi 2 (Te x Se 1-x ) 3 and (Bi x Sb 1-x ) 2 Te 3 thermoelectric compounds. Furthermore, these materials are used as p and n-type semiconductors to fabricate a highly compact micro-thermoelectric cooler with cross-sections of the single legs and gaps between the legs in the order of 20 × 100 μm 2 and 8 μm, respectively. The whole process has been developed with the aim of integrating the cooling device directly on a photoelectronic integrated circuit (PIC). The complex structure of the PICs including different structure heights makes the implementation of mechanical polishing or bonding processes difficult. The electrodeposition of the materials in such small structures comes together with an edge effect that is translated in an extremely fast and dendritic growth. Direct ultrasonication of the electrolyte during the depositions has shown best results completely overcoming the edge effect, thus allowing to produce well defined structures with high spatial resolution. Moreover, this study is complemented by the analysis of the cooling performance by finite element simulations using experimental thermoelectric properties measured on continuous films.