Fig. 1: Density profiles, experimental setup, and XFROG results.
From: Photon deceleration in plasma wakes generates single-cycle relativistic tunable infrared pulses
a The measured on-axis plasma densities (the blurred curves show the RMS spread of the data) at different blade positions (275, 400, and 525 μm from the edge of the opening) into the gas jet. The resulting plasma density profile has three distinct regions—PC: pulse compressor (black dashed line); IR-CON: IR converter (black dotted line); OC: output coupler (black dash-dot line). b Schematic of the experimental setup. In the IR pulse generation section, the drive laser (red) is focused onto Gas jet 1 (hydrogen) with a movable blade to interact with the plasma structure (see “Methods”). In the IR pulse transport section, the transmitted light from Gas jet 1 is split by a CaF2 wedge into two beams: one is sent after being filtered by an uncoated Ge plate to energy meter for IR energy measurement; the other is filtered (ITOs) and coupled to the XFROG device—Gas jet 2 (argon) followed by a spectrometer. c–e The measured XFROG traces for the corresponding plasma density profiles shown in (a). The black dashed lines mark the position of 405 nm (λref/2). Both four-wave difference-frequency and sum-frequency generated spectra (FWDFG and FWSFG, respectively) can be seen.
