Fig. 1: The fast-gain laser as a platform for realizing an active lattice in a synthetic dimension.
From: Collective quench dynamics of active photonic lattices in synthetic dimensions
a, Fast-gain ring laser. It is electrically pumped and has a section that is electrically modulated near the resonance frequency of the cavity Ω, with detuning Δ and depth Jm, which emits a multimode spectrum (multicolour beam, cf. equation (1)). The modulated section drives a standing electromagnetic wave (purple), which translates through the gain to resonant phase modulation. b, Typical photonic state (red) after condensation to the bottom of the energy band, for example a pulse, and the steady state of a fast-gain modulated laser (green). The intensity in a fast-gain laser is clamped to a non-zero constant value, as every fluctuation in the intensity is suppressed by either gain g or gain saturation −gI/Is. This generates an artificial surface for the light, which is characteristic of liquids. c, Synthetic-dimension lattice composed of modes with free spectral range Ω. At time t = t0, the modulation is turned on, and the initial single-mode state (top, green) is quenched to modes that are parametrically coupled with effective hopping C. Detuned modulation leads to an on-site energy tilting (electric field) Δ (cf. equation (2)). d, The resulting band structure inherits its shape from the modulation. In the same space, the two photonic states from b are expected to produce different dynamics in their photonic lattices due to the nature of their stabilization mechanism. Typical non-Hermitian or nonlinear emulators will be local in momentum (top). The fast-gain platform has an equalized population in the reciprocal space (bottom).
