Low-energy fermions in semi-Dirac systems depict linear momentum dispersion along one direction while having the features of parabolic dispersion in the other direction. Equilibrium optical responses of such highly anisotropic dispersion are manifested in the direction-dependent optical conductivity tensor. Going beyond the equilibrium framework, we probe the effects of optical-pumping-led nonequilibrium carrier distribution on this system's transmission and polarization rotation. Within the equation of motion approach for a two-band density matrix, we obtain a quasi-steady-state solution for a continuous-wave illumination, in which the population of the two bands is characterized by nonthermal occupancy factors with a strong dependence on amplitude, polarization, and frequency of the pump field. We demonstrate that tuning the pump field parameters significantly modifies the optical conductivity tensor for the probe field, which can have important practical consequences such as selective transmission and tunable hyperbolicity.

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• Optical conductivity
• Two-dimensional electron system
• Density matrix methods