Recent studies showed that fruit flies can detect and respond to the direction of motion of odor filaments as they cross their two antennae, independent of wind direction. In this talk, I will describe our investigation into where and how that motion computation occurs in the fly olfactory system. The circuit we have identified is the first described olfactory motion detector in any animal. It shares key features with visual motion detection circuitry in flies and mammals, suggesting that motion detection across species and sensory modalities may share a limited set of neural implementations. 

A widely tunable free spectral range (FSR) is a key requirement for many microresonator applications, yet it remains challenging to achieve on conventional monolithic platforms. In this talk, I present optical microresonators based on the Surface Nanoscale Axial Photonics (SNAP) platform, in which whispering-gallery modes are confined by nanoscale axial variations in an optical fiber. I review recent experiments demonstrating continuous and extensive FSR tuning – from sub-picometer to tens of picometers – using simple mechanical control, including fiber bending, relative translation, and milliradian rotation of intersecting straight fibers, while maintaining high Q-factors. These results are supported by a theory that maps SNAP microresonators onto an effective one-dimensional Schrödinger equation and coupled wave equations, enabling systematic design of the microresonator spectrum and profile with globally or locally constant FSR. Together, these results establish a flexible route to compact, mechanically reconfigurable microresonators for the realization of miniature tunable frequency comb generators, delay lines, photonic signal processors, and ultra-precise optical sensors.

Photon counting opens a door into a new world. Quantum effects emerge. Beyond fundamental interest, those effects lead to unprecedented accuracy in measuring light, often surpassing the capabilities of classical sensors. Quantum-enabled photonic techniques can enhance nearly every traditional application in optics: from astronomy to biology and from communications to imaging. I will talk about our recent experiments with faint light that enable practical quantum advantage by demonstrating below-the-shot-noise sensitivity and super-resolution. Let me show you a new world that connects fundamental laws of nature with everyday optical technologies.

Bio: Dr. Sergey V. Polyakov is the Chief of the Quantum Measurement Division, Physical Measurement Laboratory at NIST. He oversees the broad spectrum of research projects, from fundamental and applied quantum information science to the identification and dissemination of fundamental physical constants and units that form the international measurement system (also known as Système international d'unités, or SI). His own research aims to develop quantum methods for characterizing faint light. Sergey contributed to early research efforts in quantum repeaters. He developed innovative methods of single-photon source characterization that led to in situ, non-invasive measurement of the underlying physics of single-photon emitters. He holds the world record in the verification of the accuracy of single-photon detector calibration. Recently, he invented and developed a new class of optical receivers for classical communications that use quantum measurement. Sergey is a Fellow of the Optical Society of America and has served as a General Chair of CLEO (2021), and Nonlinear Photonics topical meeting (2022).

The intermediate band solar cell (IBSC) concept has been proposed to overcome the efficiency limits of single-junction devices. In IBSCs, mid-gap states in the host material create an additional intermediate absorption pathway for below-bandgap photons, increasing the short-circuit current without compromising the open-circuit voltage. We have shown that submonolayer CdTe QDs grown by MBE-MEE and embedded in ZnCdSe, latticed matched to InP, can be employed in IBSCs without the formation of a detrimental wetting layer be fabricated with near-optimal IBSC parameters. Hundreds of QD-containing layers can be grown, which is particularly important for addressing the inherently low absorption in IBSCs, and especially those using type-II QDs.  We present results from recently grown CdTe/ZnCdSe type-II QDs that exhibit deeper PL emission, indicating the formation of larger QDs required for an optimized IB energy position.

In addition, we present theoretical considerations for increasing light absorption in these solar cells. Distributed Bragg reflectors (DBRs) are an attractive choice to recycle photons and enhance absorption. We demonstrate optimization techniques for the inverse design of broadband (1 to 1.8 µm) and wide-angle (0 to 70°) DBRs operating in this spectral range, specifically modeling a DBR using ZnCdSe/ZnCdMgSe lattice-matched to InP. The total photon absorption was chosen as the figure of merit for the optimized structures. We show that the proposed design offers excellent broadband reflectivity with strong robustness against fabrication errors.