Topological methods have opened exciting opportunities across fields, from condensed matter to photonics. Time-reversal symmetry breaking, an essential ingredient to engineer nontrivial Chern phases, can be achieved with an electric bias in nonequilibrium situations, for example in time-variant systems or in systems with drifting electrons [1-3].
Recently, we introduced a novel non-Hermitian electro-optic effect with chiral gain governed by the Berry curvature dipole of low-symmetry metallic systems [2-3]. Applying a static electric bias modifies the optical conductivity, breaking electromagnetic reciprocity and producing a non-Hermitian response with gain. Notably, the active or dissipative nature of the material response is dependent on the handedness of the electromagnetic wave. For example, for waves polarized to the right, the response may be active (with optical gain), while the opposite handedness results in a dissipative response. In this talk, we will discuss the topological roots of the non-Hermitian linear electro-optic effect. We will also show how the chiral gain offers a pathway to realize chiral topological lasers, where the orbital angular momentum of the laser mode is closely tied to the electric field bias orientation.