  We show that the effective gauge field for photons provides a versatile
platform for controlling the flow of light. As an example we consider a
photonic resonator lattice where the coupling strength between nearest neighbor
resonators are harmonically modulated. By choosing different spatial
distributions of the modulation phases, and hence imposing different
inhomogeneous effective magnetic field configurations, we numerically
demonstrate a wide variety of propagation effects including negative
refraction, one-way mirror, and on and off-axis focusing. Since the effective
gauge field is imposed dynamically after a structure is constructed, our work
points to the importance of the temporal degree of freedom for controlling the
spatial flow of light.
