With the continuous development of medicine, optics, chemistry, communication and other fields, various micro total analysis system, lab-on-a-chip, micro electro mechanical systems and high-precision micro-nano devices began to appear and are gradually used. Most of these systems or structures are realized by preparing three-dimensional micro-nano connected structures in transparent materials by femtosecond laser. Therefore, the main technologies of femtosecond laser preparation of three-dimensional micro-nano structures are introduced, the main applications of micro-nano connectedstructures are summarized, the existing problems of current femtosecond laser preparation of three-dimensional micro-nano connected structures are put forward, and the technology is prospected.

Non-diffracting beams have attracted attention in recent years due to their unique properties, such as diffraction-free propagation and self-repairing and self-accelerating ability, which make them promising candidates for microscopic imaging applications. Non-diffraction beams can suppress beam diffraction during propagation, thereby improving the imaging resolution. Moreover, their self-healing characteristic facilitates quick wave-front recovery after passing through a strongly scattering medium, enhancing imaging depth and signal-to-noise ratio. Their self-acceleration feature expands the detection dimension of light field information, enabling multi-dimensional reconstruction imaging. Based on the characteristics of several biological micro-imaging technologies, this paper discusses the application and research progress of non-diffracting beams, specifically Bessel and Airy beams, in high-resolution biological micro-imaging.

Laser-induced forward transfer has application prospects in three-dimensional metal microstructure printing. Pulse duration is a critical factor that influences the droplet transfer behavior, but droplet generation and deposition behavior under different pulse durations are unclear at present. In this study, 500 nm copper films were used as the research object to perform a laser-induced forward transfer experiment at five pulse durations. The results show that with an increase in pulse duration, the minimum and maximum energy fluence thresholds of the laser-induced forward transfer process to form complete microdroplets gradually increase, and the pulse duration significantly influences the morphology of deposited microdroplets. Based on the experiment, the processing map of laser-induced forward transfer under different pulse durations was plotted, and the material transfer rates of microdroplet deposition at different pulse durations were calculated. Finally, the large-area microdroplets array was printed using the scan head line-scanning method.

As an important device for the application of terahertz technology, the terahertz modulator has a wide application prospect in the fields of terahertz communication, imaging, and sensing. However, current terahertz modulators exhibit problems, such as low modulation depth, narrow operating bandwidth, and poor stability. This restricts further promotion and development of terahertz technology. In this study, a new optical control GaAs/side-polished terahertz fiber (SPTF) modulator is demonstrated. GaAs film is transferred to the polished region of the terahertz fiber to enhance the interaction with the terahertz evanescent wave. The highest modulation depth of GaAs/ SPTF modulator is 97.4% with an external laser irradiation of 808 nm. The experimental results show that this new fiber modulator exhibits a good optical control modulation effect. Additionally, the compact and highly integrated design of the device suggests its broad application potential.