We report a simple and robust method to fabricate highly sensitive and transparent silver nanorod (AgNR) array substrates for surface enhanced Raman scattering (SERS) using low temperature oblique angle deposition technique. These highly sensitive AgNR SERS substrates consist of tilted AgNRs deposited on glass slides at a substrate temperature T = 140 K. The results show that the substrate temperature plays a crucial role in determining both the morphology and the length of AgNRs. The SERS enhancement activity of these substrates was determined using trans-1,2-bis(4-pyridyl) ethylene as a Raman probe molecule. The highest SERS response was obtained from 1 μm long AgNRs fabricated at T = 140 K. Such a deposition reduces the deposition time to 1/4 when compared to similar length AgNRs deposited at room temperature. The effect of the manifestly different surface morphology of low temperature deposited AgNRs on the SERS enhancement is demonstrated by finite-difference time-domain calculations of local field enhancements. The AgNRs arrays grown at 140 K exhibit uniform SERS response and good optical transmission and are cost-effective, which makes this fabrication method a practical choice as a next generation alternative for SERS substrate fabrication.

A comprehensive model of ultrafast laser-induced plasma generation intended for coupling with pulse propagation simulations in transparent solids is introduced. It simultaneously accounts for the changing spectrum of a propagating ultrashort laser pulse while coupling to the evolution of the energy-resolved nonequilibrium free-carrier distribution. The presented results indicate that strong pulse chirps lead to ionization dynamics that are not captured by the standard monochromatic treatment of laser-induced plasma formation. These results have strong implications for ultrafast laser-solid applications that depend on ionization in a strong nonlinear focus.

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Plasmonic materials that strongly interact with light are ideal candidates for designing subwavelength photonic devices. We report on direct coupling of terahertz waves in metallic nanorods by observing the resonant transmission of surface plasmon polariton waves through lithographically patterned films of silver nanorod (100 nm in diameter) micro-hole arrays. The best enhancement in surface plasmon resonant transmission is obtained when the nanorods are perfectly aligned with the electric field direction of the linearly polarized terahertz wave. This unique polarization-dependent propagation of surface plasmons in structures fabricated from nanorod films offers promising device applications. We conclude that the anisotropy of nanoscale metallic rod arrays imparts a material anisotropy relevant at the microscale that may be utilized for the fabrication of plasmonic and metamaterial based devices for operation at terahertz frequencies.

The advanced radiographic capability (ARC) laser system, part of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, is a short-pulse laser capability integrated into the NIF. The ARC is designed to provide adjustable pulse lengths of ∼ 1 − 38 p s in four independent beamlets, each with energies up to 1 kJ (depending on pulse duration). A detailed model of the ARC lasers has been developed that predicts the time- and space-resolved focal spots on target for each shot. Measurements made to characterize static and dynamic wavefront characteristics of the ARC are important inputs to the code. Modeling has been validated with measurements of the time-integrated focal spot at the target chamber center (TCC) at low power, and the space-integrated pulse duration at high power, using currently available diagnostics. These simulations indicate that each of the four ARC beamlets achieves a peak intensity on target of up to a few 10 18 W / c m 2 .