Directional transport and nonlinear localization of light in a one-dimensional driven-dissipative photonic lattice

TL;DR

Problem: dynamic control of light transport and localization in photonic lattices beyond static geometry. Approach: a 1D lattice of 31 coupled micropillars driven by two coherent pumps with a controllable phase difference $Δφ$, analyzed with a coupled photon–exciton model and a Fourier-space analytical solution. Contributions: demonstrated optical switching between OFF and ON states, directional propagation tunable by $Δφ$ and detuning $Δ/t$, and nonlinear localization of extended modes via Kerr interaction $g_X$, including a phase-matching condition $Δφ + k_0 (m_2 - m_1) = (2ℓ+1)π$; localization persists under moderate disorder due to dissipation and is influenced by oscillator-strength saturation. Significance: shows interference engineering as a versatile tool for tunable light confinement in lattices with richer band structures, enabling reconfigurable photonic devices and potential exploration of nonlinear/topological effects.

Abstract

Photonic lattices facilitate band structure engineering, supporting both localized and extended modes through their geometric design. However, greater control over these modes can be achieved by taking advantage of the interference effect between external drives with precisely tuned phases and photonic modes within the lattice. In this work, we build on this principle to demonstrate optical switching, directed light propagation and site-specific localization in a one-dimensional photonic lattice of coupled microresonators by resonantly driving the system with a coherent field of controlled phase. Importantly, our experimental results provide direct evidence that increased driving power acts as a tuning parameter enabling nonlinear localization at frequencies previously inaccessible in the linear regime. These findings open new avenues for controlling light propagation and localization in lattices with more elaborate band structures.

Figures (5)

• Figure 1: (a) Schematic representation of the 1D lattice consisting of 31 micropillars, with a center-to-center separation of $a = 2.5 \, \mu\text{m}$. The excitation spots are on adjacent pillars, with equal amplitudes $F$ and phase difference $\Delta\phi$. (b) Angle-resolved photoluminescence measurement of the 1D lattice with one pump spot, showing the energy bands as a function of the in-plane momentum $k_x$, with $\Delta = Ep - E_0$, where $E_0 = 1445.13 \, \text{meV}$. The white line represents the fitted two coupled exciton-photon model. The blue and orange dashed lines indicate the laser energy pumped at the top of the band ($\Delta/t = 1.87$) and at zero energy ($\Delta/t = 0$), respectively. (c, d) Real-space emission and corresponding line profiles for the OFF ($\Delta\phi = 0$) and ON state ($\Delta\phi = \pi$), both with excitation at the top of the band. (e, f) Real-space emission and corresponding line profiles showing rightward propagation ($\Delta\phi = \pi/2$) and leftward propagation ($\Delta\phi = -\pi/2$), both with excitation at $\Delta/t = 0$.
• Figure 2: (a) Schematic of the 1D lattice consisting of 31 micropillars, with excitation spots with equal phase $\Delta\phi = 0$ and enveloping a single site. (b, c) Real-space emission for three values of $\Delta/t = -0.21$, $0.75$, and $1.87$, along with their corresponding line profiles. (d) $\Delta/t$ scan spanning from the bottom to the top of the dispersion band, presented for two cases: a single excitation spot on the 15th site -green dots-, and with two excitation spots on the 15th and 17th sites -blue dots-.
• Figure 3: (a)-(f) Power dependence of the localization parameter for six different detunings $\Delta/t$: -0.21, 0, 0.10, 0.25, 0.35, and 0.55. (g) Line profiles for three different powers (1 mW, 31 mW, and 71 mW) at a detuning of $\Delta/t = 0.35$, indicated by different markers in (e). (h) Maximum localization power ($P_{\text{maxloc}}$) as a function of the first five detunings. For $\Delta/t = 0.55$, $P_{\text{maxloc}}$ is not included in (h) as nonlinearity-induced localization is no longer observed.
• Figure 4: (a) Numerical results for the $\lambda$ dependence on pump power for the same detuning settings as in the experiments in Fig. \ref{['fig:3']}, with $g_x \neq 0$. (b) Maximum localization power ($P_{\text{maxloc}}$), as a function of detuning $\Delta/t$.
• Figure 5: Line profile showing the intensity counts for both the experiment and numerical simulations at $\Delta/t = -0.04$, highlighting the presence of stray light (yellow shadow).