Nonlinear post-compression in multi-pass cells in the mid-IR region using bulk materials

We numerically investigate the regime of nonlinear pulse compression at mid-IR wavelengths in a multi-pass cell (MPC) containing a dielectric plate. This post-compression setup allows for ionization-free spectral broadening and self-compression while mitigating self-focusing effects. We find that self-compression occurs for a wide range of MPC and pulse parameters and derive scaling rules that enable its optimization. We also reveal the solitonic dynamics of the pulse propagation in the MPC and its limitations and show that spatiotemporal/spectral couplings can be mitigated for appropriately chosen parameters. In addition, we reveal the formation of spectral features akin to quasi-phase matched degenerate four-wave mixing. Finally, we present two case studies of self-compression at 3-μm and 6-μm wavelengths using pulse parameters compatible with driving high-field physics experiments. The simulations presented in this paper set a framework for future experimental work using few-cycle pulses at mid-IR wavelengths.Air Force Office of Scientific Research (FA9550-16-1-0121); National Nuclear Security Administration (DE-NA0003960); Agencia Estatal de Investigación (PID2019-106910GB-I00)

Quantitative Chemically-Specific Coherent Diffractive Imaging of Buried Interfaces using a Tabletop EUV Nanoscope

Characterizing buried layers and interfaces is critical for a host of applications in nanoscience and nano-manufacturing. Here we demonstrate non-invasive, non-destructive imaging of buried interfaces using a tabletop, extreme ultraviolet (EUV), coherent diffractive imaging (CDI) nanoscope. Copper nanostructures inlaid in SiO2 are coated with 100 nm of aluminum, which is opaque to visible light and thick enough that neither optical microscopy nor atomic force microscopy can image the buried interfaces. Short wavelength (29 nm) high harmonic light can penetrate the aluminum layer, yielding high-contrast images of the buried structures. Moreover, differences in the absolute reflectivity of the interfaces before and after coating reveal the formation of interstitial diffusion and oxidation layers at the Al-Cu and Al-SiO2 boundaries. Finally, we show that EUV CDI provides a unique capability for quantitative, chemically-specific imaging of buried structures, and the material evolution that occurs at these buried interfaces, compared with all other approaches.Comment: 12 pages, 8 figure

Multiple beam ptychography for high throughput data acquisition

We extend ptychography CDI to allow for imaging of multiple areas on a sample simultaneously using multiple identical beams. This enables high throughput imaging of large samples without increased data collection or loss in resolution

Multiple beam ptychography for large field of view imaging

We present an extension of ptychography coherent diffractive imaging that enables simultaneous imaging of several areas of an extended sample using multiple, spatially separated interfering beams. We show that this technique will increase the throughput of an imaging system by a factor that is equal to the number of beams used. This allows for the acquisition of large field of view images with near diffraction-limited resolution without an increase in data acquisition. This represents a significant step towards large field of view, high resolution imaging in the EUV and x-ray energy regimes

Reflection mode tabletop coherent diffraction imaging of buried nanostructures

We image a nanostructured sample through a visibly-opaque 100nm layer of aluminum using lensless Fresnel Ptychography and a tabletop high harmonic source. The reconstructed amplitude-contrast image uncovered the presence of interfacial diffusion non-destructively

Spatial, spectral, and polarization multiplexed ptychography

We introduce a novel coherent diffraction imaging technique based on ptychography that enables simultaneous full-field imaging of multiple, spatially separate, sample locations. This technique only requires that diffracted light from spatially separated sample sites be mutually incoherent at the detector, which can be achieved using multiple probes that are separated either by wavelength or by orthogonal polarization states. This approach enables spatially resolved polarization spectroscopy from a single ptychography scan, as well as allowing a larger field of view to be imaged without loss in spatial resolution. Further, we compare the numerical efficiency of the multi-mode ptychography algorithm with a single mode algorithm. (C) 2015 Optical Society of Americ

Tabletop extreme ultraviolet reflection mode coherent diffractive imaging of buried structures

We demonstrate non-invasive, high-resolution non-destructive reflection mode imaging of nanostructures buried beneath 100 nm of visibly opaque aluminum using ptychographic coherent diffractive imaging with 29.1 nm extreme ultraviolet light produced by tabletop high harmonic source. © OSA 2016

Multiple beam ptychography for large field-of-view, high throughput, quantitative phase contrast imaging

The ability to record large field-of-view images without a loss in spatial resolution is of crucial importance for imaging science. For most imaging techniques however, an increase in field-of-view comes at the cost of decreased resolution. Here we present a novel extension to ptychographic coherent diffractive imaging that permits simultaneous full-field imaging of multiple locations by illuminating the sample with spatially separated, interfering probes. This technique allows for large field-of-view imaging in amplitude and phase while maintaining diffraction-limited resolution, without an increase in collected data i.e. diffraction patterns acquired. (C) 2017 Elsevier B.V. All rights reserved

Spatial, spectral, and polarization multiplexed ptychography

We demonstrate ptychographic imaging of multiple areas of a sample simultaneously with no loss of resolution, by using different wavelengths or polarizations to collect independent diffraction patterns in parallel. This significantly reduces imaging times