Coupling Magnons to an Opto-Electronic Parametric Oscillator

TL;DR

The paper presents the optoelectronic-magnonic parametric oscillator (OEMPO), a hybrid platform that couples YIG magnon modes to parametrically pumped OEPO photons, enabling long-distance, distributed magnon–photon interactions. By integrating a nonlinear electrical mixer-driven pump and phase-tunable loops, the authors realize both degenerate and nondegenerate auto-oscillations with on-demand mode pairing and frequency comb-like spectra. They observe clear photon–magnon anti-crossings (≈28.8 MHz) and grand anti-crossings when nondegenerate mode pairs couple to magnons, consistent with a Jaynes–Cummings-like interaction, and develop a robust analytical model to capture the coupled dynamics. The OEMPO offers high tunability, multimode hybridization, and coherent phase operations, positioning it as a modular component for future distributed hybrid magnonic networks and quantum signal processing applications, with the potential for phase-controlled, long-range magnon–photon coupling. $f_p$ and $rac{f_p}{2}$ are central to the operation, enabling parametric generation independent of cavity delay.

Abstract

Hybrid magnonic systems have emerged as versatile modular components for quantum signal transduction and sensing applications owing to their capability of connecting distinct quantum platforms. To date, the majority of the magnonic systems have been explored in a local, near-field scheme, due to the close proximity required for realizing a strong coupling between magnons and other excitations. This constraint greatly limits the applicability of magnons in developing remotely-coupled, distributed quantum network systems. On the contrary, opto-electronic architectures hosting self-sustained oscillations has been a unique platform for longhaul signal transmission and processing. Here, we integrated an opto-electronic oscillator with a magnonic oscillator consisting of a microwave waveguide and a Y3Fe5O12(YIG) sphere, and demonstrated strong and coherent coupling between YIG's magnon modes and the opto-electronic oscillator's characteristic photon modes - revealing the hallmark anti-crossing gap in the measured spectrum. In particular, the photon mode is produced on-demand via a nonlinear, parametric process as stipulated by an external seed pump. Both the internal cavity phase and the external pump phase can be precisely tuned to stabilize either degenerate or nondegenerate auto-oscillations. Our result lays out a new, hybrid platform for investigating long-distance coupling and nonlinearity in coherent magnonic phenomena, which may be find useful in constructing future distributed hybrid magnonic systems.

Figures (5)

• Figure 1: Schematic illustration of the OEMPO experimental setup. The central system is a standard OEO, consisting of an optical path (RFoF system with O-E and E-O conversions), and an electrical path, forming a cavity loop. An external pump (right dashline-enclosed box), injecting a pump tone, $\rm f_p$, can be integrated to the OEO and transforming the system to a standard OEPO. Either nondegenerate ($\rm f_{p1},f_{p2}$ and $\rm f_{p1}+f_{p2} = f_p$) or degenerate ($\rm \frac{f_p}{2}$) auto-oscillation modes can be induced inside the cavity. Another probe system consists of a YIG magnonic resonator (left dashline-enclosed box) can be inserted into the loop to realize coherent coupling between the magnon modes and the OEPO's photon modes, via the pump-induced three-magnon splitting and confluence process ($\rm f_m \rightarrow \frac{f_m}{2} + \frac{f_m}{2}$). SW: switch (manual connection), SG: signal generator, PhS: phase shifter, A: amplifier, vATN: variable attenuator, BPF: band-pass filter, SA: spectrum analyzer, CPL: coupler, D: diode, MZM: Mach-Zehnder modulator. The different configurations can be adjusted by the two SWs. OEO: SW$_1$ and SW$_2$ both at position-1; OEMO: SW$_1$ at position-1, SW$_2$ at position-2; OEPO: SW$_1$ at position-2, SW$_2$ at position-1. OEMPO: SW$_1$ and SW$_2$ both at position-2.
• Figure 2: (a) OEO power spectrum showing the intrinsic cavity loop mode, $\rm f_o$, at 2.65 GHz, and the 2nd harmonic mode, 2$\rm f_o$, at 5.3 GHz. (b) OEPO power spectrum showing the half-pump frequency harmonics, $\frac{\rm f_p}{2}$, at 3 GHz, and the pump frequency, $\rm f_p$, at 6 GHz. (c,d) Evolution of the power spectrum by tuning the cavity loop phase, via changing the $V_{\varphi1}$ in PhS$_1$, for the (c) OEO loop mode at $\rm f_o =$2.65 GHz, and (d) OEPO oscillation modes near the half-pump harmonics, $\frac{\rm f_p}{2} = 3$ GHz.
• Figure 3: (a) OEPO power spectrum scanned in a broader frequency range from 2 to 4 GHz (2000 MHz span), showing the spectral envelope, at selective, representative $V_{\varphi1}$ values, (top to bottom) 1, 2.55, 4, and 7V. (b) The corresponding fine scan of the power spectrum of the shaded area in (a), from 2.9 to 3.1 GHz (200 MHz span), at the same $V_{\varphi1}$ values. The mode spacing of the mode-pair displayed in (b) at $V_{\varphi1}=4$V is 6 MHz, half of the full FSR (12 MHz).
• Figure 4: (a) The OEPO power spectrum scanned near the $\rm \frac{f_p}{2}$ mode at different pump phases, via tuning the $V_{\varphi2}$ in the PhS$_2$. The $V_{\varphi1}$ is fixed at 1.89V to stabilize the $\rm \frac{f_p}{2}$ mode during the scan. (b) A line-cut scan at 3 GHz of the power spectrum in (a). A global maximum is observed around $V_{\varphi2} \sim 4.5$V, and a local maximum is observed around $V_{\varphi2} \sim 0.3$V. The phase difference between the local maximum and the global maximum is calculated to be $\sim \pi$.
• Figure 5: Photon-magnon coupling between the YIG's magnetostatic mode and the OEPO's characteristic photon modes measured via the probe subloop. (a,b) The $f-H$ dispersion spectra of the YIG magnon couples to: (a) the degenerate, single-mode $\rm \frac{f_p}{2}$ auto-oscillation, and (b) the nondegenerate mode-pairs, akin to a photonic frequency comb. The corresponding OEPO power spectrum is also displayed for each case, which is detected using an auxiliary spectrum analyzer. The OEPO spectral response exhibits a long-term stability during the concurrent $f-H$ dispersion measurements.