Figure 1
From: An intense, few-cycle source in the long-wave infrared
Layout for the LWIR generation, (a) The output of a 20 mJ Ti:Sapph 800 nm laser is separated with a beam splitter (BS) to pump an optical parametric amplifier (OPA) with 18 mJ, 26 fs pulses at 1 kHz. The OPA generates 6 mJ of signal + idler, up to 4.2 mJ of this beam are used in a dichroic mirror (DM) based interferometer to generate LWIR pulses via difference frequency generation in a AgGaS2(I) crystal (AGS). The OPA is filtered using a pair anti-reflective coated Zinc Selenide (ZS) and Germanium (Ge) windows. The Fresnel reflection off the Ge window is filtered with an additional Ge window so residual leakage from the LWIR beam can be recorded on a pyroelectric detector (PyD) for single-shot power tagging. A periscope sends the remaining pulse energy (>95%) into an experimental chamber with a ZS window and a −25 mm spherical concave mirror (F) to back focus the few-cycle LWIR pulse in Xenon (Xe) gas. A pair of electrostatic lenses guide the Xe ions onto a micro-channel plate (MCP) detector for time-of-flight measurements. A small portion of the remaining 2 mJ beam (pink), split prior to the OPA, is used as a gating field in the XFROG. Mirror M is removed from the periscope to couple the LWIR pulse into the XFROG for electric field characterization. Ion Time of Flight (iTOF), (b) A typical time of flight spectrum for Xe+ when ionized with 8.9 μm pulse. XFROG, (c) A measured XFROG spectrogram for an 8.9 μm laser field.
