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Title: Observation of backward high-harmonic emission from solids

Here, we experimentally demonstrate backward emission of high-harmonics of a near-infrared laser from MgO and Si crystals in the direction of specular reflection. We show that the variation of the high-harmonic power with the angle of incidence can be predicted with nonlinear reflection coefficients derived originally for perturbative nonlinearities. A comparison of transmission and reflection geometries suggests that backward-propagating high-harmonics are an excellent reference to study nonlinear propagation of intense light in solids. Backward emission will enable phase matching of the high-harmonic beam and the integration of the functionalities of extended gas-phase high-harmonic beamlines into a single optical element. The potential to achieve phase matching paves the way to solid-state based high-harmonic sources with higher flux than the best transmission-based sources, where high-harmonics are strongly absorbed by the crystal itself.
 [1] ;  [1] ;  [1] ;  [1] ;  [2]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; FA9550-14-1-0108; Early Career Research Program
Accepted Manuscript
Journal Name:
Optics Express
Additional Journal Information:
Journal Volume: 26; Journal Issue: 9; Journal ID: ISSN 1094-4087
Optical Society of America (OSA)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Nonlinear optics at surfaces; Multiharmonic generation; Optical nonlinearities of condensed matter
OSTI Identifier: