Inherent intensity noise suppression in a mode-locked polycrystalline Cr:ZnS oscillator.

We developed a diode-pumped, mode-locked polycrystalline Cr:ZnS oscillator using single-walled carbon nanotubes as a saturable absorber. The oscillator exhibits self-start mode-locking operation, generating sub-100 fs pulses with an average power of 300 mW. We found a unique feature in which the intensity noise originating from relaxation oscillation is suppressed by inherent second harmonic generation in polycrystalline Cr:ZnS.

Antimonene Nanoflakes: Extraordinary Photoacoustic Performance for High-Contrast Imaging of Small Volume Tumors.

Photoacoustic imaging (PAI) has evolved to a stage that high-performance exogeneous contrast agents are urgently needed for imminent biomedical and clinical applications. Given that a material meets the basic criteria of efficient photoacoustic conversion, high biocompatibility, and fast excretion, great effort has been devoted to evaluating various materials for developing advantageous contrast agents to explore the full potentials of PAI. One focus is through modification of the current agents to boost their PA performance; whilst the other focus is to develop novel agents.

All-normal-dispersion passive harmonic mode-locking 220 fs ytterbium fiber laser.

We report a stable passive second-harmonic mode-locked all-normal-dispersion ytterbium fiber laser based on nonlinear polarization evolution. This fiber laser has two polarization beam splitter output ports for optimizing the output spectrum 5 ps duration pulses with 187 mW average power being generated at the harmonic repetition rate of 99.6 MHz.