We present a promising method for creating high-density ensembles of nitrogen-vacancy centers with narrow spin-resonances for high-sensitivity magnetic imaging. Practically, narrow spinresonance linewidths substantially reduce the optical and RF power requirements for ensemble-based sensing. The method combines isotope purified diamond growth, in situ nitrogen doping, and helium ion implantation to realize a 100 nm-thick sensing surface. The obtained 10 17 cm −3 nitrogen-vacancy density is only a factor of 10 less than the highest densities reported to date, with an observed spin resonance linewidth over 10 times more narrow. The 200 kHz linewidth is most likely limited by dipolar broadening indicating even further reduction of the linewidth is desirable and possible.The nitrogen-vacancy (NV) center in diamond is a versatile room-temperature magnetic sensor which can operate in a wide variety of modalities, from nanometerscale imaging with single centers [1, 2] to sub-picotesla sensitivities using ensembles [3]. Ensemble-based magnetic imaging, utilizing a two-dimensional array of NV centers [4][5][6], combines relatively high spatial resolution with high magnetic sensitivity. These arrays are ideal for imaging applications ranging from detecting magnetically tagged biological specimens [7,8] to fundamental studies of magnetic thin films [9]. A key challenge for array-based sensors is creating a high density of NV centers while still preserving the desirable NV spin properties. Here we report on a promising method which combines isotope purified diamond growth, in situ nitrogen doping and helium ion implantation. In the 100 nmthick sensor layer, we realize an NV density of 10 17 cm −3 with a 200 kHz magnetic resonance linewidth. This corresponds to a a DC magnetic sensitivity ranging from 170 nT (current experimental conditions) to 10 nT (optimized experimental conditions) for a 1 µm 2 pixel and 1 second measurement time.Magnetic sensing utilizing NV centers is based on optically-detected magnetic resonance (ODMR) [10][11][12]. In the ideal shot-noise limit, the DC magnetic sensitivity is given by [9] in which h/gµ B = 36 µT/MHz, C is the resonance dip contrast, η is the photon collection efficiency, δν is the full-width at half maximum resonance linewidth, n N V is the density of NV centers in imaging pixel volume V , and t is the measurement time. From Eq. 1, it is apparent that to minimize δB ideal for a given linewidth δν, one would like to maximize the NV density n N V . Increasing n N V , however, can also increase δν. For example, lattice damage during the NV creation process can create inhomogeneous strain-fields [13]. More fundamentally, eventually NV-NV and NV-N dipolar interactions will contribute to line broadening. This dipolar broadening, δν dp , is proportional to the nitrogen density n N [14,15]. Since n N V is typically proportional to n N , we can divide δ ν into two components, δν = δν 0 + δν dp = δν 0 + An N V , to obtainin which δν 0 depends on factors independent of NV density (e.g. hyperfi...

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Intense few-cycle laser pulses have a breadth of applications in high energy density science, including particle acceleration and x-ray generation. Multi-amplifier laser system pulses have durations of tens of femtoseconds or longer. To achieve high intensities at the single-cycle limit, a robust and efficient post-compression scheme is required. We demonstrate a staged compression technique using self-phase modulation in thin dielectric media, in which few-cycle pulses can be produced. The few-cycle pulse is then used to generate extreme ultravoilet light via high harmonic generation at strong field intensities and to generate MeV electron beams via laser solid interactions at relativistic intensities.

Thin film compression to the single-cycle regime combined with relativistic compression offers a method to transform conventional ultrafast laser pulses into attosecond X-ray laser pulses. These attosecond X-ray laser pulses are required to drive wakefields in solid density materials which can provide acceleration gradients of up to TeV/cm. Here we demonstrate a nearly 99% energy efficient compression of a 6.63 mJ, 39 fs laser pulse with a Gaussian mode to 20 fs in a single stage. Further, it is shown that as a result of Kerr-lensing, the focal spot of the system is slightly shifted on-axis and can be recovered by translating the imaging system to the new focal plane. This implies that with the help of wave-front shaping optics the focusability of laser pulses compressed in this way can be partially preserved.

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The injection of polymethylmethacrylate (PMMA) is a minimally invasive, image-guided procedure used to treat vertebral fractures due to osteoporosis, metastatic lesions, multiple myeloma, and benign but destabilizing bone tumors. The injection of PMMA into the C2 vertebral body using the transoral technique has been reported in three separate patients for treatment of benign tumors (a vertebral hemangioma and an aneurysmal bone cyst) and for multiple myeloma in the third patient. Although the injection of PMMA into the vertebral body is most commonly performed to treat benign vertebral compression fractures, a transoral C2 approach has not been reported in the English literature as a treatment for a benign fracture of C2. We report the treatment of a fracture and nonunion of the base of the dens and a subarticular fracture of the vertebral body of C2 using a bilateral transoral approach.

Generation of an extreme ultraviolet continuum (33 eV to 72 eV) by a multi millijoule, few-cycle (7 fs) laser pulse produced by the Thin Film Compression technique.

Ultrafast lasers (< 500 fs) have enabled laser-matter interactions at intensities exceeding 10 18 Wcm −2 with only millijoules of laser energy. However, as pulse durations become shorter, larger spectral bandwidths are required. Increasing the bandwidth causes the temporal structure to be increasingly sensitive to spectral phase, yet measuring the spectral phase of a laser pulse is nontrivial. While direct measurements of the spectral phase cannot be done using square-integrable detectors, phase information can be reconstructed by measuring the spectral response of a nonlinear optical effect. We introduce a new deep learning approach using the generalized nonlinear Schrödinger equation and self-phase modulation, a χ3 nonlinearity occurring from material propagation. By training a neural network on numerical simulations of pulses propagating in a known material, the features of spectral change can be use to reconstruct the spectral phase. The technique is also sensitive to the local fluence of the pulse, enabling the full temporal intensity profile to be calculated. We demonstrate our method on a simulated large bandwidth pulse undergoing moderate material dispersion, and an experimentally produced broadband spectrum with substantial material dispersion. Error rates are low, even when modest amounts of noise introduced. With a single plate of glass and an optical spectrometer, single shot phase and fluence measurements are possible in real-time on intense ultrafast laser systems.