  Unconventional Weyl points (WPs), carrying topological charge 2 or higher,
possess interesting properties different from ordinary charge-1 WPs, including
multiple Fermi arcs that stretch over a large portion of the Brillouin zone.
Thus far, such WPs have been observed in chiral materials and acoustic
metamaterials, but there has been no clean demonstration in photonics in which
the unconventional photonic WPs are separated from trivial bands. We
experimentally realize an ideal symmetry-protected photonic charge-2 WP in a
three-dimensional topological chiral microwave metamaterial. We use field
mapping to directly observe the projected bulk dispersion, as well as the two
long surface arcs that form a noncontractible loop wrapping around the surface
Brillouin zone. The surface states span a record-wide frequency window of
around 22.7% relative bandwidth. We demonstrate that the surface states exhibit
a novel topological self-collimation property and are robust against disorder.
This work provides an ideal photonic platform for exploring fundamental physics
and applications of unconventional WPs.
