Extended Data Fig. 4: Schematic of the experimental setup.

An optical pulse from the laser source is split into three optical arms: test, injection and sampling. The pulse in the test arm is down-converted to a pulse with a central wavelength of 2.1 μm. The test and injection pulses are combined with a controlled delay between them and transmitted through a sample. The injection pulse is then filtered out, while the transmitted test pulse is combined with the sampling pulse, which nonlinearly interacts with the test pulse in the detection plane, sampling its electric field. This figure was created with the online 3Doptix platform (https://3doptix.com/).