The IFLScience article Scientists Work Out How To Make Matter From Light describes photon-photon collisions producing pairs of particles, and the Nature Photonics Letter A photon–photon collider in a vacuum hohlraum describes a possible way of doing the experiment.
edit: The Phys.org article The first model for capturing and condensing light under realistic conditions discusses this as well.
Following this proposal, has a hohlaraum now been built or is in the process of being built for the purposes of serving as photon target for such an experiment?
From the abstract:
[...]The simplest mechanism by which pure light can betransformed into matter, Breit–Wheeler pair production $\gamma \gamma' \rightarrow e^+e^-$, has never been observed in the laboratory. Here, we present the design of a new class of photon–photon collider in which a gamma-ray beam is ﬁred into the high-temperature radiation ﬁeld of a laser-heated hohlraum. Matching experimental parameters to current-generation facilities, MonteCarlo simulations suggest that this scheme is capable of producing of the order of 10^5 Breit–Wheeler pairs in a single shot. This would provide the ﬁrst realization of a pure photon–photon collider, representing the advent of a new type of high-energy physics experiment.