Science Advances reports photon extraction breakthrough

Science Advances on May 20 highlighted a new paper on photon extraction from quantum emitters embedded in bulk semiconductors. The study, published in Science Advances in 2026, described inverse-designed nanostructures that create “photonic nanojets” inside high-refractive-index materials to make individual emitters easier to excite and read out. The researchers said the approach addresses two longstanding problems at once: poor photon collection from bulk materials and the difficulty of isolating one emitter from many nearby defects. ### What exactly did the researchers build? Behrooz Semnani, Sai Sreesh Venuturumilli and co-authors described monolithic photonic structures etched directly into high-index host materials. The devices were designed with free-form topology optimization and fabricated with standard top-down patterning, according to the paper. Rather than relying on a resonant cavity, the structures generate tightly confined photonic nanojets — narrow regions of concentrated light inside the material. (science.org) The Science Advances paper said those nanojets let the team selectively excite individual emitters inside a relatively dense and randomly distributed ensemble. The same geometry also improved the way emitted photons were directed out toward the collection optics, increasing usable signal while suppressing background photoluminescence from other defects near the surface and in the bulk. ### Why is photon extraction such a problem in bulk materials? (science.org) The paper said high-refractive-index host materials trap much of the light generated by solid-state quantum emitters, which lowers collection efficiency. It also said isolating a single emitter often requires unusually pure samples and precise implantation of defects, adding fabrication complexity. That matters because solid-state emitters are used as single-photon sources and spin qubits in quantum information processing, quantum telecommunication and quantum-enhanced sensing, the authors wrote. (science.org) Better extraction means more of the photons produced by an emitter can actually be measured or routed into an instrument. ### What did the experiments show? The experiments used negatively charged nitrogen-vacancy, or NV−, centers in diamond at room temperature. (science.org) The authors said they chose a low-cost diamond sample as a case study and demonstrated selective single-emitter excitation under those conditions. The paper reported a 10-fold power enhancement for selective excitation and more than a 15-fold improvement in photon extraction efficiency for photoluminescence collection in confocal microscopy. (science.org) The supplementary materials said the structure’s response was broadband across the NV fluorescence bandwidth and included simulation and experimental analysis of excitation enhancement and radiation control. ### Why did Science Advances frame this as a scalability story? (science.org) The authors said the structures work within bulk materials that host relatively dense, randomly distributed emitters, rather than only in highly curated samples. They also said the devices are monolithic and compatible with standard fabrication methods, which is why the work was presented as a route to more accessible emitter probing in bulk systems. The paper added that the method could extend beyond diamond and other NV-center systems to other semiconductor materials containing emitters. (science.org) It also said the concept could be generalized to fiber-integrated platforms, pointing to possible use in laboratory quantum communication and sensing setups that depend on efficient optical readout. That forward-looking application is the authors’ claim, not a demonstrated field deployment. ### Where can readers check the figures and methods? (science.org) Science Advances released the main paper, figures and supplementary materials online with the publication. The supplement includes device-design details, simulation settings, fabrication and optical-characterization methods, and additional analysis of broadband response and Purcell enhancement. The article is titled “Probing individual quantum emitters in bulk semiconductors via photonic nanojets,” and the corresponding authors listed in the paper are Behrooz Semnani and Michal Bajcsy. (science.org 1) (science.org 2)