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In a burning plasma state 1 – 7 , alpha particles from deuterium–tritium fusion reactions redeposit their energy and are the dominant source of heating. This state has recently been achieved at the US National Ignition Facility 8 using indirect-drive inertial-confinement fusion. Our experiments use a laser-generated radiation-filled cavity (a hohlraum) to spherically implode capsules containing deuterium and tritium fuel in a central hot spot where the fusion reactions occur. We have developed more efficient hohlraums to implode larger fusion targets compared with previous experiments 9 , 10 . This delivered more energy to the hot spot, whereas other parameters were optimized to maintain the high pressures required for inertial-confinement fusion. We also report improvements in implosion symmetry control by moving energy between the laser beams 11 – 16 and designing advanced hohlraum geometry 17 that allows for these larger implosions to be driven at the present laser energy and power capability of the National Ignition Facility. These design changes resulted in fusion powers of 1.5 petawatts, greater than the input power of the laser, and 170 kJ of fusion energy 18 , 19 . Radiation hydrodynamics simulations 20 , 21 show energy deposition by alpha particles as the dominant term in the hot-spot energy balance, indicative of a burning plasma state. In burning plasma, alpha particles from fusion reactions are the dominant source of heating. The design choices that resulted in reaching this state in experiments at the National Ignition Facility are reported.

A new ‘photon–photon collider’, which may enable elusive Breit–Wheeler pair production in an optics laboratory setting, is predicted. Using this concept, it is potentially possible to produce 10 5 Breit–Wheeler electron–positron pairs by firing a gamma-ray beam into a high-temperature radiation field of a laser-heated hohlraum cavity. The ability to create matter from light is amongst the most striking predictions of quantum electrodynamics. Experimental signatures of this have been reported in the scattering of ultra-relativistic electron beams with laser beams 1 , 2 , intense laser–plasma interactions 3 and laser-driven solid target scattering 4 . However, all such routes involve massive particles. The simplest mechanism by which pure light can be transformed into matter, Breit–Wheeler pair production (γγ′ →  e + e − ) 5 , has never been observed in the laboratory. Here, we present the design of a new class of photon–photon collider in which a gamma-ray beam is fired into the high-temperature radiation field of a laser-heated hohlraum. Matching experimental parameters to current-generation facilities, Monte Carlo simulations suggest that this scheme is capable of producing of the order of 10 5 Breit–Wheeler pairs in a single shot. This would provide the first realization of a pure photon–photon collider, representing the advent of a new type of high-energy physics experiment.

Gas sensors are important in many fields such as environmental monitoring, agricultural production, public safety, and medical diagnostics. Herein, Tamm plasmon resonance in a photonic bandgap is used to develop an optical gas sensor with high performance. The structure of the proposed sensor comprises a gas cavity sandwiched between a one-dimensional porous silicon photonic crystal and an Ag layer deposited on a prism. The optimised structure of the proposed sensor achieves ultra-high sensitivity (S = 1.9×10 5  nm/RIU) and a low detection limit (DL = 1.4×10 −7 RIU) compared to the existing gas sensor. The brilliant sensing performance and simple design of the proposed structure make our device highly suitable for use as a sensor in a variety of biomedical and industrial applications.

Dissipative solitons are localized formations of an electromagnetic field that are balanced through an energy exchange with the environment in presence of nonlinearity, dispersion and/or diffraction. Their growing use in the area of passively mode-locked lasers is remarkable: the concept of a dissipative soliton provides an excellent framework for understanding complex pulse dynamics and stimulates innovative cavity designs. Reciprocally, the field of mode-locked lasers serves as an ideal playground for testing the concept of dissipative solitons and revealing their unusual dynamics. This Review provides basic definitions of dissipative solitons, summarizes their implications for the design of high-energy mode-locked fibre laser cavities, highlights striking emerging dynamics such as dissipative soliton molecules, pulsations, explosions and rain, and finally provides an outlook for dissipative light bullets. This Review explains the concept of dissipative solitons and their application to high-energy mode-locked fibre laser cavities. Dynamics and effects such as dissipative soliton ‘explosions’ and ‘rain’ are summarized, and an outlook of the field is also provided.

Backscattering due to laser plasma instabilities (LPIs) presents a risk in the laser-driven inertial confinement fusion. Generally, it is assumed that the backscattering of laser beams in the same cone is identical in hohlraum physics studies. In the experiments performed at SG-100kJ laser facility, we find that the backscattering of laser beams in the same cone are quite different. Our investigation reveals the main reason for this phenomenon is that the laser beams in the same cone obtain different power from their neighbor beams via crossed-beam energy transfer (CBET) depending on their polarizations. The dependence of multi-beam CBET on laser polarization arrangement is confirmed in a specially designed experiment. These findings are crucial for understanding the backscattering, CBET, energy deficit and the azimuthal drive asymmetry in cylindrical hohlraums. Laser plasma instabilities are the main factors contributing to degradation of hohlraum performance in inertial confinement fusion experiments. Here, the authors show asymmetric backscattering within the same laser cone at the SG-100kJ laser facility, unveiling the role of crossed-beam energy transfer and laser polarization.

Indirect-drive hohlraum experiments at the National Ignition Facility have demonstrated symmetric capsule implosions at unprecedented laser drive energies of 0.7 megajoule. One hundred and ninety-two simultaneously fired laser beams heat ignition-emulate hohlraums to radiation temperatures of 3.3 million kelvin, compressing 1.8-millimeter-diameter capsules by the soft x-rays produced by the hohlraum. Self-generated plasma optics gratings on either end of the hohlraum tune the laser power distribution in the hohlraum, which produces a symmetric x-ray drive as inferred from the shape of the capsule self-emission. These experiments indicate that the conditions are suitable for compressing deuterium-tritium-filled capsules, with the goal of achieving burning fusion plasmas and energy gain in the laboratory.

We describe a simple and robust method to construct complex three-dimensional (3D) structures by using short synthetic DNA strands that we call \"DNA bricks.\" In one-step annealing reactions, bricks with hundreds of distinct sequences self-assemble into prescribed 3D shapes. Each 32-nucleotide brick is a modular component; it binds to four local neighbors and can be removed or added independently. Each 8-base pair interaction between bricks defines a voxel with dimensions of 2.5 by 2.5 by 2.7 nanometers, and a master brick collection defines a \"molecular canvas\" with dimensions of 10 by 10 by 10 voxels. By selecting subsets of bricks from this canvas, we constructed a panel of 102 distinct shapes exhibiting sophisticated surface features, as well as intricate interior cavities and tunnels.

The vital utilization of biosensors in different domains has led to the design of much more precise and powerful biosensors, since they have the potential to attain information in a fast and simple manner compared to conventional assays. The present review describes the basic concepts, operation, and construction of biosensors and presented an ideology that choice of categorization, selection of immobilization method and advantages are crucial factors for an efficient and commercial biosensor. Amongst various biosensors, the field effect transistor (FET)-based biosensors have shown much more potential and immense advantages such as high detection ability and sensitivity for both neutral and charged biomolecules and, hence, have been explored comprehensively in the present review. This paper discusses the current challenges in device design by mainly focusing on the quantitative and qualitative performance parameters such as sensing surface properties, signal-to-noise ratio and various other factors, since consideration of these factors will eventually address the crucial concerns related to device design and practical limitations. The critical measures to translate the commercialization of biosensors in the market at a high pace have also been discussed. Hence, the discussion on device challenges illustrates that there is a scope of improvement in the areas such as short-channel effects, specificity and nanocavity filling factor for revolutionary advances in FET-based biosensors. Optimal selection of design rules and biosensing material has the potential to feature the next generation of biosensors. The present paper reports that following integrated multidisciplinary approaches and switching to nanotechnology in designing of FET-based biosensors can offer a lot of improvements in the practical key factors (such as low cost and reliability) and opportunities for the biosensors in the marketplace.

Metallic cavities can confine light to volumes with dimensions considerably smaller than the wavelength of light. It is commonly believed, however, that the high losses in metals are prohibitive for laser operation in small metallic cavities. Here we report for the first time laser operation in an electrically pumped metallic-coated nanocavity formed by a semiconductor heterostructure encapsulated in a thin gold film. The demonstrated lasers show a low threshold current and their dimensions are smaller than the smallest electrically pumped lasers reported so far. With dimensions comparable to state-of-the-art electronic transistors and operating at low power and high speed, they are a strong contender as basic elements in digital photonic very large-scale integration. Furthermore we demonstrate that metallic-coated nanocavities with modal volumes smaller than dielectric cavities can have moderate quality factors.

The sensitivity of molecular fingerprinting is dramatically improved when the absorbing sample is placed in a high-finesse optical cavity, because the effective path length is increased. When the equidistant lines from a laser frequency comb are simultaneously injected into the cavity over a large spectral range, multiple trace gases may be identified 1 within a few milliseconds. However, efficient analysis of the light transmitted through the cavity remains challenging. Here, a novel approach—cavity-enhanced, frequency-comb, Fourier-transform spectroscopy—fully overcomes this difficulty and enables measurement of ultrasensitive, broad-bandwidth, high-resolution spectra within a few tens of microseconds without any need for detector arrays, potentially from the terahertz to ultraviolet regions. Within a period of just 18 µs, we recorded the spectra of the ammonia 1.0 µm overtone bands comprising 1,500 spectral elements and spanning 20 nm, with a resolution of 4.5 GHz and a noise equivalent absorption at 1 s averaging of 1 × 10 −10  cm −1  Hz −1/2 , thus opening a route to time-resolved spectroscopy of rapidly evolving single events. By combining Fourier transform spectroscopy with two frequency-shifted combs and cavity ring-down spectroscopy, scientists demonstrate a powerful new tool for ultrahigh sensitivity spectroscopy. The scheme can measure broadband, high-resolution spectra in tens of microseconds, does not require detector arrays and may allow tuning from terahertz to ultraviolet frequencies.