  Strain-engineered graphene has garnered much attention recently owing to the
possibilities of creating substantial energy gaps enabled by pseudo-magnetic
fields. While theoretical works proposed the possibility of creating large-area
pseudo-magnetic fields by straining monolayer graphene along three
crystallographic directions, clear experimental demonstration of such promising
devices remains elusive. Herein, we experimentally demonstrate a triaxially
strained suspended graphene structure that has the potential to possess
large-scale and quasi-uniform pseudo-magnetic fields. Our structure employs
uniquely designed metal electrodes that function both as stressors and metal
contacts for current injection. Raman characterization and tight-binding
simulations suggest the possibility of achieving pseudo-magnetic fields over a
micrometer-scale area. Current-voltage measurements confirm an efficient
current injection into graphene, showing the potential of our devices for a new
class of optoelectronic applications. We also theoretically propose a photonic
crystal-based laser structure that obtains strongly localized optical fields
overlapping with the spatial area under uniform pseudo-magnetic fields, thus
presenting a practical route towards the realization of graphene lasers.
