Welcome!

We are a research group in the Mechanical Engineering department at Caltech, led by Professor Austin Minnich. Our lab's research focus is on understanding and engineering nanoscale heat transport for applications in the energy field like thermoelectric waste heat recovery. We use a variety of experimental and theoretical techniques to investigate nanoscale transport processes, with a particular emphasis on ultrafast optical techniques. We invite you to look at the website for more details about our work and facilities.



News

Junlong's work on optical control of radiative transfer was published in Optics Express Jul. 26, 2018

Nick's work on nanotruss thermal conductitvity was published in Nano Letters Jul. 19, 2018

Lina's work on phonon transmission at crystalline-amorphous interfaces was published in Physical Review B May 31, 2018

Nick was awarded the Demetriades-Tsafka-Kokkalis Prize in Nanotechnology and Related Fields. Congrats! May 16, 2018

Ruiqiang's work was published in RSC. May 7, 2018

Nick successfully defends his thesis. Congrats! Apr 13, 2018

Xiangwen and Lina have moved on to their next positions. Congrats! Jan 13, 2018

Alex passes quals. Congrats! Sept 21, 2017

Benoit has moved on to his next position. Congrats! June 1, 2017

Zoila, Peishi, and Erika successfully pass candidacy. Congrats! May 31, 2017

Chengyun's work on phonon transmission spectra was publish in Physical Review B. May 15, 2017

News Archive

Spotlightmore

imagePaper published in Optics Express

Here, we propose a thermal modulation scheme based on optical pumping of semiconductors in near-field radiative contact. External photo-excitation of the semiconductor emitters leads to increases in the free carrier concentration that in turn alters the plasma frequency, resulting in modulation of near-field thermal radiation. The temporal frequency of the modulation can reach hundreds of kHz limited only by the recombination lifetime, greatly exceeding the bandwidth of methods based on temperature modulcation. Calculations based on fluctuational electrodynamics show that the heat transfer coefficient between two silicon films can be tuned from near zero to 600 Wm−2K−1 with a gap distance of 100 nm at room temperature. Jul. 27, 2018

imagePaper published in Nano Letters

Creating materials that simultaneously possess ultralow thermal conductivity, high stiffness, and damage tolerance is challenging because thermal and mechanical properties are coupled in most fully dense and porous solids. We report that nanolattices composed of 24- to 182-nm-thick hollow alumina beams in the octet-truss architecture possess the same ultralow thermal conductivities as aerogels while attaining specific elastic moduli that are nearly 2 orders of magnitude higher. Our work demonstrates a general route to realizing multifunctional materials that occupy previously unreachable regions within the material property space. Jul. 19, 2018

imagePaper published in Physical Review B

We examine the modal transmission and reflection processes of THz phonons across an amorphous Si region connected to two crystalline Si leads, a model interface for those that occur in nanocrystalline solids, using mode-resolved atomistic Green's functions. We find that the interface acts as a low-pass filter, reflecting modes of frequency greater than around 3 THz while transmitting those below this frequency. Further, we find that these low frequency modes travel nearly unimpeded through the interface, maintaining their wave vectors on each side of the interface. Our work shows that even completely disordered regions may not be effective at reflecting THz phonons, with implications for efforts to alter thermal conductivity in nanocrystalline solids. May 31, 2018