Dynamics of photonic crystal nanolasers based on Fano resonance

This thesis presents an investigation into the dynamics of photonic crystal Fano lasers. It combines theoretical analysis and simulations, practical application estimations, and experimental validations to deepen our understanding of laser dynamics and their potential applications. Initially, the thesis revisits the fundamental concepts and steady-state properties of Fano lasers. A new multi-section approach that includes carrier diffusion, a factor previously unexplored in Fano laser models, is developed. We investigate the model’s numerical stability for this approach and assess the deviations from previous models that assumed uniform carrier distribution. The focus then shifts to the modulation of the Fano laser’s nanocavity. Under rapid modulation, pulses with unique waveforms are generated in Fano lasers. Utilizing the concepts of Q-switching and cavity-dumping, we explain the underlying physics and examine the characteristics of those pulses. Methods for tuning the nanocavity’s refractive index, such as the free carrier effect and thermal effect, are analyzed. This analysis facilitates the construction of a modulated Fano laser model that accurately predicts pulse generation phenomena, which aligns well with experimental results. Comparisons with Fabry–Pérot lasers demonstrate the energy efficiency of Fano lasers in pulse generation. Expanding beyond conventional Fano lasers, we explore a new configuration featuring an active external feedback cavity. This structure reveals multiple oscillation modes, including optical bistability between Fano and Fabry–Pérot modes under specific nanocavity detuning conditions. This discovery sparks interest in utilizing feedback Fano lasers as flip-flop devices, potentially creating compact, energy-efficient optical memories. The characteristics of flip-flop operations are investigated, showcasing picosecond switching times and femtojoule energy consumption per bit. Preliminary experiments on prototype feedback Fano laser samples, although not yet exhibiting bistability, reveal multiple modes consistent with theoretical predictions. Opticalthermal characteristics of these samples are also measured. An analytical comparison between two coupled cavities nanolasers and waveguide-nanocavity systems highlights our system’s stability and absence of mode oscillation. Finally, the focus changes to the stochastic simulation of nanolasers, using a quantum-based approach distinct from the semi-classical methods used in previous chapters. We revisit two stochastic methods—the fixed time increment (FTI) method and Gillespie’s first reaction method (FRM)—and compare their characteristics and computational efficiency. The focus is on the behavior of nanolasers in near-threshold regions, where we successfully capture the photon burst phenomenon with quantum dot laser configurations. We also calculate the deviations between analytical solutions and those obtained from the two stochastic methods and analyze the photon statistics of pulses generated during laser turn-on transients. In summary, this thesis pushes the boundaries of understanding the nanolaser dynamics based on Fano resonance, exploring new configurations and operating methods, and laying the groundwork for future photonics and optical computing innovations.