AI Insight
Researchers simulated an integrated optical device where light pulses write and read magnetic states in a thin GdFeCo film integrated with a silicon nitride waveguide. Using multiphysics simulations combining optical, thermal, and magnetic dynamics, they demonstrated that an 800 nm pump pulse can reverse approximately 86% of the magnetic film, with this switching efficiency remaining stable across a wide range of pulse energies. A subsequent 532 nm probe pulse can read out the magnetic state through polarization changes, with Faraday and Kerr rotations showing high sensitivity to the magnetic configuration, though standard transmission measurements showed minimal variation.
Why it matters
This work advances the development of integrated photonic devices for all-optical magnetic memory and data storage, potentially enabling faster and more energy-efficient computing systems. The detailed modeling provides design guidelines for waveguide-integrated magneto-optical devices and demonstrates that polarization-based readout methods are necessary for detecting magnetic states in such systems.
⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: In an integrated all-optical magnetic device, a guided pulse writes a magnetic state and a later optical signal reads it out. We study both steps for an 8 nm GdFeCo film inserted across a Si$_3$N$_4$ waveguide. A three-dimensional dispersive finite-difference time-domain calculation gives the energy absorbed from an 800 nm pump pulse. This energy drives a four-temperature model and calibrated stochastic two-sublattice Landau-Lifshitz-Bloch dynamics. After relaxation, a separate 532 nm probe is propagated through the fixed magnetic state for the optical readout. At the reference pump fluence, the model reverses 0.859 of the film from either saturated state. The switched fraction remains within 0.81-0.87 over a 2.4-fold range of incident fluence. A threshold rule applied to the local absorption map reproduces the five three-dimensional simulation points to within $8times10^{-4}$, showing that, within the model, incomplete reversal results from non-uniform guided-mode absorption. When the film starts from zero magnetization, thermal noise orients the recovered local moments at random; over 16 realizations, $0.502 pm 0.004$ of the cells end with a negative $x$ component of the FeCo moment. Among the simulated states, the probe transmission, reflection, and absorption fractions vary by at most 0.02. The magnetic Faraday and Kerr rotations are much more sensitive and become about 12 and 130 times smaller, respectively, in the stochastically recovered state than in a saturated film. The reflected signal also contains a magnetization-independent geometric background, which can be removed by subtracting a reference signal. These results link the switching efficiency to the guided-mode absorption profile and predict polarization-based readout of the simulated magnetic states. The model assumes a homogeneous film and neglects spatial exchange stiffness and subsequent domain coarsening.