Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session RR04: V: Ultrafast Spectroscopy: Applications and Techniques |
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Sponsoring Units: DLS Chair: Samuel Teitelbaum, Arizona State University Room: Virtual Room 4 |
Tuesday, March 21, 2023 11:30AM - 11:42AM |
RR04.00001: Vibrational coherent control of intervalley scattering in monolayer WSe2 Chenyu Wang The past two decades have witnessed significant development in our ability to selectively excite specific vibrational modes as coherent phonons, providing an avenue towards engineering the functional properties of quantum materials with light [1,2]. In particular, the intervalley scattering mediated by coherent phonons in monolayer transition metal dichalcogenide family has inspired the great potential of manipulating valley polarization which concerns the realization of practical valleytronics [3]. However, most previous theoretical works based on the Fermi's golden rules deal with evolution of electrons and phonons adopting a quasi-thermal distribution [4] and fail to capture the nonthermal scattering dynamics when the system is driven far from equilibrium. |
Tuesday, March 21, 2023 11:42AM - 11:54AM |
RR04.00002: Observation of a Quantized Vortex Vanishing in Exciton-Polariton Superfluids Daegwang Choi, Min Park, Byoung Yong Oh, Min-Sik Kwon, Suk In Park, Dogyun Ko, Meng Sun, Ivan G Savenko, Jin Dong Song, Yong-Hoon Cho, Hyoungsoon Choi In semiconductor microcavity, exciton-polaritons are bosonic quasi-particles that can create a quantized vortex by Laguerre-Gaussian (LG) pump laser. Here, we report an observation of a vanishment of a quantized vortex in exciton-polariton superfluids. In a non-resonant LG pump laser, polariton condensates can be confined under the optical potential, resulting in multistate condensates consisting of a rotating excited state and a stationary ground state. In time-resolved spectroscopy with pulsed excitation, we observed that the excited state, a polariton vortex, decayed to the ground state over time. Furthermore, our experimental results are in excellent agreement with the theoretical calculations employing the driven-dissipative Gross–Pitaevskii equation coupled with pumping reservoirs. |
Tuesday, March 21, 2023 11:54AM - 12:06PM |
RR04.00003: Giant nonlinearity in VS2-black phosphorus nanohybrid under femtosecond pulses VINOD KUMAR, Chandra S Rout, K V Adarsh Generating a large optical nonlinearity from hybrid nanoparticles is beneficial for a wide range of applications, such as optical limiting, optical switching, all-optical data processing, and quantum information. A complex vanadium disulphide−black phosphorus (VS2/BP) nanohybrid with strong interlayer coupling was synthesized by a one-pot hydrothermal method to achieve enhanced third-order nonlinearity for optical limiting applications. In this strongly coupled VS2/BP nanohybrid, we demonstrate experimentally and theoretically a highly efficient scheme of excited-state absorption (ESA) and refraction by charge transfer. Due to the highly efficient charge transfer at ultrafast time scales between VS2 and BP, we observed the enhancement in the third-order nonlinear optical response by orders of magnitude compared to VS2, which shows saturable absorption and one order of magnitude compared to BP, which shows weak two-photon absorption. Moreover, first-principle-based calculations using the density functional theory and Bader charge analysis show the electrons are transferred from VS2 to BP, verified by steady-state and time-resolved photoluminescence measurements. By using the nonlinear optical response of the nanohybrid, we have designed a high-performance liquid cell-based ultrafast optical limiter with important device parameters such as the optical limiting onset of 5 mJ/cm2 along with low limiting differential transmittance 0.6 in the femtosecond regime. |
Tuesday, March 21, 2023 12:06PM - 12:18PM |
RR04.00004: Novel correlation spectroscopy measurements through femtosecond pulse induced supercontinuum generation Debabrata Goswami In the femtosecond pulse induced supercontinuum generation process, there is pulse splitting beyond a certain incident intensity. These split pulses show mutual coherence resulting in spectral interference. As the amount of pulse splitting increases with the amount of incident laser power, the interference is eventually washed out at high enough powers. We present distinctly structured interferometric features in femtosecond supercontinuum generation with incident laser powers, which are near threshold for supercontinuum generation. We argue that near threshold, these structures arise from the coherent superposition of pulses that are split initially into two daughter pulses during the supercontinuum generation process. An increase in the input pulse energy results in generating multiple daughter fragments in the temporal domain, which eventually reaches an extent that correlated interference structures are not measurable. Properties of the split pulse are different in different supercontinuum generation media as their propagation characteristics change given the different environments. This can be of immense use and application in spectroscopic applications and in coherence correlation measurements. |
Tuesday, March 21, 2023 12:18PM - 12:30PM |
RR04.00005: Vibrational response functions for multidimensional electronic spectroscopy in the adiabatic regime: A coherent-state approach Frank E Quintela, Filippo Troiani Multi-dimensional spectroscopy represents a particularly insightful tool for investigating the interplay of nuclear and electronic dynamics, which plays an important role in a number of photophysical processes and photochemical reactions. Here, we present a coherent state representation of the vibronic dynamics and of the resulting response functions for the widely used linearly displaced harmonic oscillator model. Analytical expressions are derived for M-th order response functions of an N-level system, with coherent- and thermal-state initialization of the oscillator(s). The formal derivation is translated into a simple recipe, whereby the explicit analytical expressions of the response functions can be derived directly from the Feynman diagrams. Finally, the application of a non-Hermitian Hamiltonian approach is discussed, which allows us to extend the above results to the case of vibrational relaxation. |
Tuesday, March 21, 2023 12:30PM - 12:42PM |
RR04.00006: Why a magnetized semiconducting quantum wirecan act as an optical amplifier Manvir S Kushwaha The fundamental issues associated with the magneto-roton excitations are investigated in a quantum wire characterized by a confining harmonic potential and subjected to a perpendicular magnetic field. Essentially, we embark on the device aspects of the intersubband collective (magnetoroton) excitation which observes a negative group velocity between the maxon and the roton. The computation of the gain coefficient suggests an interesting and important application: the electronic device based on such magnetoroton modes can act as an optical amplifier1. 1. M.S. Kushwaha, Phys. Rev. B 78, 153306 (2008); J. Appl. Phys. 109, 106102 (2011); Europhys. Lett. 123, 34001 (2018); Mod. Phys. Lett. B 33, 1950062 (2019). |
Tuesday, March 21, 2023 12:42PM - 12:54PM |
RR04.00007: Start-to-end Software Model of CPA and NLO Systems Jack E Hirschman, Randy A Lemons, Minyang Wang, Sergio Carbajo Modeling chirped pulse amplification (CPA) and nonlinear optical (NLO) systems from start to end (S2E) is essential to efficiently drive laser research and applications. Such models can help expand high power laser system designs routinely tackled with human-centered methodologies in far ranging sectors from basic science research to defense and national security to a wide array of commercial applications. S2E models can even enable reverse engineering of a laser system, allow for streamlined exploration of parameter spaces for experimental setups, aid in inverse design of materials, or train machine learning models for optimization and tuning of these systems. |
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