EPFL Demonstrates Millimeter-Wave-to-Optical Transducer with 67% Internal Efficiency
AI-summarised brief · reviewed before publication
Researchers at EPFL’s Hybrid Photonics Laboratory and Center for Quantum Science and Engineering have built an integrated electro‑optic transducer that links millimeter‑wave (mm‑wave) signals to telecom‑band optical photons with an internal conversion efficiency of 67 %. The device couples a thin‑film lithium‑niobate (TFLN) photonic molecule to a sub‑millimeter metallic resonator, achieving a vacuum electro‑optic coupling rate of about 60 kHz. By etching photonic‑crystal mirrors into a suspended 400 nm TFLN membrane, the team created two Fabry–Pérot microcavities that align the optical doublet splitting with the adjacent quarter‑wavelength resonator, eliminating the mode‑volume mismatch that plagued earlier designs. Operating in a reversed‑dissipation regime, the transducer isolates a narrow spectral slice of room‑temperature thermal mm‑wave photons, enabling precise cooperativity measurements. Although off‑chip wireless efficiency is limited by free‑space coupling (≈1.6 × 10⁻⁴), replacing the gold resonator with a high‑gap superconductor such as NbTiN could suppress internal losses and raise total efficiency at liquid‑helium temperatures.
💡 Why It Matters
- · By achieving high internal efficiency in a compact, cryogenically compatible platform, the transducer paves a practical route for linking superconducting quantum processors with optical fiber networks, a key step toward scalable distributed quantum computing.
