News & Views Discharging excitons: fast and at will Picosecond pulses of terahertz light used for rapid and reversible switching of charged excitons (trions) into neutral excitons in a two-dimensional semiconductor open perspectives for high-speed optoelectronic devices and fundamental studies of new electronic phases of matter. Stéphane Berciaud News & Views 02 Dec 2024 Ultra-low-noise terahertz sources Oscillators for tunable terahertz waves with ultra-high spectral purity may pave the way for precise molecular clocks and extremely high-data-rate wireless communications. Thomas Schneider News & Views 02 Dec 2024 Attosecond X-ray laser vision Diling ZhuDavid A. Reis News & Views 02 Dec 2024 Scrutinizing liquid molecules A new attosecond metrology technique for studying light–molecule interactions in liquids may open the door for variety of attosecond applications in chemistry and biology. Mohammed Th. Hassan News & Views 02 Dec 2024 Two in one Implementing stable lasers often requires complex packaging of multiple devices, such as stand-alone external cavities and isolators. Now, stabilizing and isolating lasers can be realized in a single silicon chip thanks to the Kerr nonlinear effect in a resonator. Mohamad Hossein IdjadiFirooz Aflatouni News & Views 02 Dec 2024 Switching it up Light upconversion and bistable optical switching is achieved via positive photonic feedback by integrating a photoactive layer with a tandem OLED. Gert-Jan A. H. Wetzelaer News & Views 02 Dec 2024 Top of page ⤴ Meeting Reports Optical computing and artificial intelligence Light-based processing and machine learning featured heavily in San Diego at the 2024 SPIE Optics + Photonics conference. Enthusiasm was coupled with questions related to the real-world applicability and the merits of linear vs non-linear, and all-optical vs hybrid, approaches. David Pile Meeting Report 02 Dec 2024 Top of page ⤴ Review Articles Advances in inverted perovskite solar cells The authors review recent advances in inverted perovskite solar cells, with a focus on non-radiative recombination processes and how to reduce them for highly efficient and stable devices. Xin ZhangShengfan WuJunhao Chu Review Article 28 Oct 2024 Top of page ⤴ Articles High-brightness transition metal-sensitized lanthanide near-infrared luminescent nanoparticles Cr3+-sensitized lanthanide-doped nanoparticles afford high-brightness luminescence in the near-infrared region for applications in in vivo non-invasive bioimaging. Jiang MingYing ChenFan Zhang Article 13 Sept 2024 Brillouin laser-driven terahertz oscillator up to 3 THz with femtosecond-level timing jitter A Brillouin laser-driven terahertz oscillator is developed. The phase noise level of the generated terahertz waves is less than –100 dBc Hz–1, translating to timing noise below 10 as Hz–1/2 at 10 kHz Fourier frequency, over a carrier frequency range from 300 GHz to 3 THz. Brendan M. HeffernanJames GreenbergAntoine Rolland Article 13 Sept 2024 Regulating phase homogeneity by self-assembled molecules for enhanced efficiency and stability of inverted perovskite solar cells Amorphous phases of self-assembling molecules employed as a hole-transporting layer in inverted perovskite solar cells contribute to homogeneous perovskite film growth, resulting in a power conversion efficiency of 25.20% (certified 24.35%) for one-square-centimetre area cells. Xi WangJia LiYi Hou Article 18 Sept 2024 Highly efficient circularly polarized near-infrared phosphorescence in both solution and aggregate Two chiral enantiomers, R- and S-BBTI, are found to efficiently emit near-infrared circularly polarized phosphorescence with a large dissymmetry factor of 0.013 in dilute solutions. Dan LiuWen-Jin WangBen Zhong Tang Article 30 Sept 2024 Sub-Doppler spectroscopy of quantum systems through nanophotonic spectral translation of electro-optic light A nonlinear nanophotonic resonator is used to spectrally translate an electro-optic frequency comb to a controllable set of wavelengths between 600 nm and 1,050 nm, with comb properties that are advantageous for high-resolution spectroscopy preserved. David A. LongJordan R. StoneKartik Srinivasan Article 02 Oct 2024 Terawatt-attosecond hard X-ray free-electron laser at high repetition rate Using the European XFEL free-electron laser, researchers demonstrate terawatt-scale, attosecond hard X-ray pulses. Ten pulse trains per second, each containing hundreds of pulses at megahertz repetition rates, are achieved. Such short and intense pulses at high repetition rate enable unprecedented damage-free X-ray measurements with attosecond temporal resolution. Jiawei YanWeilun QinGianluca Geloni Article Open Access 25 Nov 2024 Positive-feedback organic light-emitting diodes and upconverters Integrating an organic photodiode with a tandem OLED enables positive photonic feedback that results in bistable behaviour. Devices show giant hysteresis in their current–voltage–luminance characteristic and upconversion of near-infrared to visible light with 100-fold photon-to-photon gain. Raju LampandeJon-Paul S. DesOrmeauxNoel C. Giebink Article 13 Sept 2024 Unified laser stabilization and isolation on a silicon chip Both laser stabilization and isolation are demonstrated simultaneously by using Kerr nonlinearity in a high-Q silicon nitride ring resonator to self-injection lock a distributed-feedback laser, bringing on-chip lasers closer to real-world fully integrated applications. Alexander D. WhiteGeun Ho AhnJelena Vučković Article 15 Oct 2024 Free-form dual-comb spectroscopy for compressive sensing and imaging By incorporating time-programmable frequency combs, free-form dual-comb spectroscopy enables compressive sensing at factors of up to 155, with a corresponding reduction in acquisition time without sacrificing spectral resolution. Fabrizio R. GiorgettaSimon PotvinEsther Baumann Article 30 Sept 2024 Near-petahertz fieldoscopy of liquid Near-petahertz electric field detection of few-femtosecond pulses with a temporal resolution of 200 attoseconds and subfemtojoule sensitivity is experimentally demonstrated, paving the path towards high-resolution biological spectro-microscopy. Anchit SrivastavaAndreas HerbstHanieh Fattahi Article Open Access 21 Oct 2024 Terabit-scale high-fidelity diamond data storage A diamond storage medium that uses fluorescent vacancy centres as robust storage units provides a high storage density of 14.8 Tbit cm−3. Jingyang ZhouJia SuJiangfeng Du Article 27 Nov 2024 Single-chip photonic deep neural network with forward-only training Researchers experimentally demonstrate a fully integrated coherent optical neural network. The system, with six neurons and three layers, operates with a latency of 410 ps. Saumil BandyopadhyayAlexander SluddsDirk Englund Article 02 Dec 2024 Ultrafast switching of trions in 2D materials by terahertz photons Using short pulses in the terahertz spectral range following optical injection, ultrafast excitation of trions to excitons and free carriers in monolayer MoSe2 can be realized within picoseconds, advancing nanoscale optoelectronics devices. Tommaso VenanziMarzia CuccuAlexey Chernikov Article 23 Sept 2024