The mid-infrared (mid-IR) spectral region contains abundant molecular vibrational and rotational information and is of significant importance for applications in molecular spectroscopy, biomedical detection, environmental monitoring, and materials processing. Meanwhile, the mid-IR region encompasses multiple important atmospheric transmission windows, offering potential advantages for free-space and space-based optical communications, while also providing new opportunities for ultrafast optical information transmission and encoding. Therefore, developing high-performance mid-IR ultrafast light sources and further exploring their rich pulse dynamics are of great significance for advancing mid-IR light sources and their potential applications.

Optical information encryption is a pivotal technology for secure optical communication. However, channel noise, chromatic dispersion, and timing jitter can readily compromise the integrity of transmitted data. The encryption scheme based on ghost imaging relies on two-path coincidence detection and offers inherent advantages in physical-layer security. Although using a low-intensity-resolution detector in the test path may reduce communication bandwidth, such a low-resolution detector can substantially lower hardware costs and system complexity, thereby enhancing the system's practical applicability. Nevertheless, systematic experimental verification and quantitative evaluation of the impact of such low-resolution detectors on multi-bit transmission remain inadequate.

Optical vortices are phase-singularity beams carrying orbital angular momentum, finding important applications in optical communications, quantum science, optical tweezers, and related fields. In recent years, significant interest has arisen in controlling optical vortex lines in three-dimensional space to form topological knot structures such as Hopf links and trefoil knots. Traditionally, the generation of such complex light fields has relied on devices like spatial light modulators (SLMs), but these systems typically suffer from limited operating bandwidth and require bulky, cumbersome optical setups. Although liquid-crystal phase plates and metasurfaces enable compactness, they remain essentially two-dimensional planar devices and face two major challenges: constrained design space and significant errors introduced by phase quantization. Therefore, how to utilize genuine three-dimensional fabrication techniques to precisely control optical wavefronts and generate complex topological vortex structures represents an urgent problem to be solved.

Aiming at a low-noise 1.5 μm band laser amplifier within an all-fiber structure, this work proposes a pumping scheme that effectively mitigates intensity noise degradation in the low-frequency range. It achieves a Watt-level laser output with low intensity noise, providing a vital technological foundation for the light sources required in future ground-based gravitational wave detection systems, and contributing to the advancement of low-noise light sources for precision measurement.