1. Ultrafast laser interaction with nanomaterials

Ultrafast optics and nanophotonics provide attosecond temporal resolution and sub-nanometer spatial resolution, enabling direct observation and manipulation of the transient motion of electrons within nanomaterials. This has significantly advanced the development of various fields, including optoelectronics, nanoelectronics, nanomaterial processing, photocatalysis, and biotechnology.

When lasers are focused onto nanomaterials, they can excite collective electron oscillations and phenomena such as surface plasmon polaritons, which lead to a significant enhancement of the electric field in specific areas of the nanostructure. By modulating the parameters of the laser pulse, it is possible to precisely detect and control the electron emission process.

Based on the ultrafast laser-driven nanoparticle ion momentum detection theoretical model and experimental setup of our research group, we are dedicated to uncovering the dynamics of electron tunneling ionization in nanomaterials. We aim to accurately measure the nonlinear optical response time of nanomaterials and ultimately achieve an isolated attosecond electron pulse source driven by ultrafast lasers.

2. Ultrafast laser interaction with atoms and molecules

In the early 19th century, ultra-fast cameras were used to answer the question of whether horses lift all four feet off the ground while running. With the emergence of femtosecond laser and the development of laser technology, people can explore the movement of electrons and the physical processes of molecular vibration and rotation from the perspective of atoms and molecules. The time scale of electron movement in atoms and molecules has reached attosecond level, and the study of ultrafast electron dynamics has important guiding significance for understanding the interaction between light and matter, revealing the mechanism of chemical reaction, and exploring the mystery of the quantum world. We will use theoretical analysis and numerical simulation to observe and regulate the electron dynamics process on the subperiodic time scale around the phenomena of strong field ionization and strong field excitation induced by ultra-short laser pulses, laying a foundation for understanding the motion laws of the micro world.

3. Nanomaterial-Enhanced Photodetection and Photocatalysis

The light absorption characteristics of semiconductor nanomaterials are determined by their band structure, and they often have the disadvantages of weak absorption and difficulty in tuning the absorption band edge, resulting in lower photoelectric conversion efficiency for semiconductor nanomaterials. Metallic nanounits with plasmonic resonance have a higher absorption cross-section, and the absorption peak can be tuned across the entire ultraviolet-visible-infrared spectrum. The localized electromagnetic field enhancement from plasmonic resonance increases light absorption and scattering, generating hot electrons, which provides various means of control to improve the semiconductor photodetection process.

Our research group constructs plasmonic metal/semiconductor composite nanounits to achieve plasmon resonance-enhanced photoelectric conversion (including photodetection and photocatalysis), with a particular focus on the optimization of interfaces to regulate the ultrafast dynamics of charge carriers (including hot carriers) in terms of generation, relaxation, and transport. This approach aims to develop efficient photodetectors and photocatalysts.

4. Laser Detection Technology and Applications

1) Highly sensitive real-time trace gas detection based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology. Our newly developed detection equipment uses laser spectroscopy methods for trace gas detection, capable of providing high sensitivity, high precision, non-contact real-time identification and quantitative analysis for gas molecules in the air with concentrations less than one part per billion. It has a wide range of applications in fields such as national defense security, environmental monitoring, industrial manufacturing, and medical diagnostics.

2) Liquid detection based on laser Raman and laser fluorescence spectroscopy techniques. We employ multi-wavelength laser spectroscopy technology, integrating traditional laser fluorescence spectroscopy with laser absorption spectroscopy, to explore and achieve a wide range, high precision, real-time, in-situ measurement of parameters such as water quality indicators and alcohol concentrations.

3) Laser imaging radar. The laser radar imaging technology we have developed has high spatial and temporal resolution and can directly form a four-dimensional image of the target. The system can be mounted on aircraft, ships, or installed on underwater vehicles such as submarines and underwater robots. It can stably acquire four-dimensional images of small targets on the surface and under the sea, such as ships, islands, reefs, and the sea surface, making it an effective monitoring technology. It can also be used for underwater engineering installation and maintenance, underwater environmental monitoring, rescue and salvage operations, seabed topography surveying, underwater marine life remote sensing, and seabed oil extraction for marine development.