One of the research areas of ARTgroup is thermal management of lighting technologies especially light emitting diodes (LEDs). In our group, we work on coming up with innovative ideas and extending them for the proper thermal management of photonic systems. In this regard, we apply both experimental and simulation approaches to understand different thermal phenomena as well as to predict temperature. Our goal is to improve the existing thermal management and increase the efficiency of the systems. 

Thermal and optical characterization: Immersion liquid cooled photonics devices

A direct passive liquid cooling technique has been investigated on bare and dip coated phosphor converted LEDs. While the previous approaches were focused on improving thermal passage toward the PCB or heat sink, this study introduces liquid cooling technique that directly targets heat generation regions and significant optical and thermal performance enhancements are observed. Direct liquid cooling decreases the temperature of the phosphor coating and prevents thermal quenching of phosphor. In this technique, a 30-fold increase in heat removal from LED exterior surfaces is achieved compared to conventional air cooling. While the ability of this technique is mainly governed by the thermal conductivity of the coolant, this encapsulation technique can be used in high power electronics packaging in different size scales. 

Three-step schematic showing the silicone gel encapsulation process for an electronic chip inside a ceramic enclosure. (a) Initial droplets of silicone elastomer are dispensed at the edges of the enclosure. (b) Additional droplets spread across the liquid surface due to surface tension, creating a creeping flow for complete coverage. (c) The silicone cures to form a solid, dome-shaped encapsulation over the chip.

Series of photographs and schematics showing phosphor coating on an LED package. The top row displays LED chips with different phosphor volume densities (50% and 20%) before and after liquid encapsulation. Insets show magnified views of the phosphor layer. The bottom row illustrates the dipping process, phosphor sedimentation during curing, and final liquid encapsulation using silicone material.Two spectral radiant flux plots comparing dry and liquid-cooled LED operation at drive currents of 250 mA, 350 mA, and 450 mA. Each graph spans wavelengths from 400–750 nm and shows multiple emission peaks. Solid lines represent air-cooled measurements and dashed lines represent liquid-cooled measurements. Figure (a) highlights peak emission around 550 nm with an arrow, while (b) shows broader spectral behavior

Non-contact temperature measurement of photonics devices: EVAtherm system

ARTgroup has been working on the non-contact temperature measurement techniques over the last decade. Our lab has developed and demosntrated a patented approach which is more accurate than many other commerically available devices.

EVAtherms system

Patented EVAtherm system for junction temperature measurement of photonic devices 

Selected research articles: