CPA - Postdoc Launch Seminar 2026 - VIII
Dear Postdocs,
The final Caltech Postdocs Launch seminar of the season is this Friday!
We've got two exciting talks from Dr. Simo Pajovic (EAS) and Dr. Prabhat Prakash
(CCE), whose titles and abstracts can be found below.
And as always - FREE Lunch and beverages will be there before the talk starts. To make sure we can order enough food, please RSVP here beforehand: https://forms.gle/EWCeN7J3WQsYfbAY6.
Please also note the change of location! We're in Noyes 153 this week rather than our usual Chen 130 location.
What – Caltech Postdocs Launch
When – Friday, 2nd of October, 2026, 11:45 AM. Talks start at 12.
Where – Noyes 153
Hope to see you there!
Best wishes,
Postdoc Launch Team
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Dual-polarized, nonreciprocal absorption of mid-infrared light
Dr. Simo Pajovic
In the photonic design of thermal emitters, emission and absorption processes are coupled via reciprocity or Kirchhoff's law of thermal radiation, stated as the equality of spectral directional emissivity and absorptivity. Although this coupling can be useful in the design and characterization of thermal emitters, it also constrains them and fundamentally limits our ability to control thermal emission. It has been experimentally demonstrated that applied magnetic fields can enable nonreciprocity in thermal emission via magneto-optical effects, with doped InAs emerging as the most popular material platform for these experiments. However, existing designs have been limited to p-polarized light in the Voigt configuration, where nonreciprocity is the strongest. Since thermal emission is unpolarized, s-polarized light ultimately has a parasitic effect on nonreciprocity. Thus, to take full advantage of both polarizations, we design a fabrication-compatible photonic crystal slab that supports both s- and p-polarized nonreciprocal thermal emission and absorption. Using finite-difference time-domain and finite-element method simulations, we demonstrate that our design supports resonances that couple to both s- and p-polarized light. The emission/absorption peaks corresponding to these resonances shift differently for forward- and backward-propagating light as a result of the applied magnetic field—a signature of nonreciprocity. This simultaneous coupling to both polarizations eliminates the parasitic channel and enhances the polarization-averaged nonreciprocal emissivity/absorptivity. Finally, we fabricate our design via electron-beam lithography and experimentally demonstrate dual-polarized nonreciprocal absorption in the 11-20 μm spectral range, near the peak wavelength of room-temperature thermal emission (10 μm). Ultimately, our design is a step toward the complete control of light as heat, enabling more efficient energy conversion, better thermal management, and new capabilities in mid-infrared photonics.
How grain-boundaries enable binder-free Solid-state Batteries
Dr. Prabhat Prakash
Molecular crystal electrolytes are an emerging class of soft-solid electrolytes in which crystalline grains are naturally embedded in fluidlike, nanoconfined grain-boundaries (GBs) that can be engineered as efficient ion-conducting pathways. For adiponitrile-LiPF6 cocrystals, we systematically tune the GB volume fraction using crystal size control and in different stoichiometric compositions, and model the diffusion, and structure, with molecular dynamics (MD) to establish a GB-centric design framework for solid-state batteries. The simulations reveal that Li+ motion in the crystalline grains is subdiffusive, while GB regions behave as disordered nanochannels with Li+ concentrations an order of magnitude higher than in equivalent - saturated salt solutions. The transport within GB microenvironment translates to high ionic conduction at mesoscale. The simulation driven understanding of nanoconfined GB engineering can be used as a scalable and tailored strategy to combine high ionic conductivity with improved interfacial compliance in solid-state battery electrolytes.