One of the most promising candidates to use as compact high sensitivity magnetometers is the Nitrogen-Vacancy (NV) center, however traditional implementations of this technology are plagued by low collection efficiencies or poor signal contrasts of the Optically Detected Magnetic Resonance (ODMR). Laser Threshold Magnetometry (LTM) offers a path towards both efficient signal collection and high signal contrasts by taking advantage of near threshold laser dynamics. We demonstrate an infrared LTM using a Vertical External Cavity Surface Emitting Laser (VECSEL) with an intra cavity diamond plate doped with NV centers. The VECSEL was tuned to the spin dependent absorption line of the NV centers, which tied the VECSEL output power to the magnetic field sensed by the NV centers. Furthermore, the contrast and the projected sensitivity limit are shown to improve when operating close to the lasing threshold. We measure a sensitivity of 7.5 nT/√ Hz between 10-50 Hz with a contrast of 18.4% and a projected Photon Shot Noise Limited (PSNL) sensitivity of 26.6 pT/√ Hz close to threshold. We also observe a saturable absorption-like effect near threshold, which further enhances the signal contrast and projected PSNL near threshold. A rate equation model for the VECSEL threshold magnetometer is described and is fit to mimic the observed threshold dynamics.
The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory contains a 192-beam 4.2 MJ neodymium glass laser (around 1053 nm or 1w) that is frequency converted to 351nm light or 3w. It was built to access the extreme high energy density conditions needed to support the nation’s nuclear stockpile in the absence of further underground nuclear tests, including studying Inertial Confinement Fusion (ICF) and ignition in the laboratory.
Over the last year, important results have been obtained demonstrated a fusion yield of 1.35MJ with 1.9MJ of laser energy (and 440 TW power) injected in the target, bringing the NIF to the threshold of ignition [2-3]. As the yield curve near ignition is steep, the laser performance team has focused on providing improved power accuracy and precision (better shot-to-shot reproducibility) with a high-fidelity pulse shaping system (HiFiPS), and also on extending the NIF operating power and energy space by 15% to 2.2MJ and 500TW.
The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory contains a
192-beam 4.2 MJ neodymium glass laser (around 1053 nm or 1w) that is frequency converted to
351nm light or 3w. It has been designed to support the study of Inertial Confinement Fusion (ICF)
and High Energy Density Physics (HEDP). The NIF Precision Diagnostic System (PDS) was reactivated and new
diagnostic packages were designed and fielded that offer a more comprehensive suite
of high-resolution measurements. The current NIF laser performance will be presented as well as the preliminary results obtained with the various laser experimental campaigns using the new diagnostic tool suites.
KEYWORDS: Diagnostics, National Ignition Facility, Cameras, Near field, Wavefronts, Sensors, Signal to noise ratio, Calibration, Near field optics, Imaging systems
The Precision Diagnostic System (PDS) is an advanced set of laser diagnostic tools installed within the National Ignition Facility (NIF). It is capable of picking off a single, full aperture, 1053nm (1ω) beamline before the beam propagates to the target chamber and directing it to a suite of precision laser diagnostics. It was instrumental in validating the performance of the final optics 3Ω frequency conversion system design when NIF was built. The PDS has recently been recommissioned after more than a decade of non-use and enhanced to better understand laser performance limitations1 and to characterize underperforming beams. In addition to recommissioning existing diagnostics for calorimetry, power, wavefront, near-field and far-field imaging, new diagnostics have been added: two types of time-resolved near field imaging systems; higher resolution wavefront imaging; and a 1ω spectrometer. Additionally, the beam transport system was upgraded to allow PDS to select among four different 1ω beamlines to enable improved understanding of beam-to-beam variations. Two of these four beams are top-hemisphere beams, while two are bottom-hemisphere, with known performance variations. The results from NIF Shots with the new and recommissioned PDS diagnostic (spatial resolution, dynamic range, time gating, etc..) will be reviewed and data up to 14 kJ, 3.2 TW will be presented.
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