Several applications of glass nanofibers have been proposed for the past years. We found a new method for production of nanofibers with a diameter of 100 nm order from thin glass plates by irradiation with nanoseconds pulsed UV laser (wavelength is 355 nm). Although the generation of nanofibers from the back surface of a glass plate is convenient for continuous laser irradiation and collection of fibers, the details of the mechanism have not been elucidated yet. In this paper, we focused on the dynamics of ejection of glass melts that results in the formation of nanofibers, and investigated the mechanism of nanofiber generation. Based on the observation by a high-speed camera, we found that voids inside of the glass plate propagated in the laser propagation direction shot by shot, then, the void pushed the molten glass near the back surface. We also confirmed that the molten glass was ejected from the back surface of plates at a speed of 10-100 m/s. We assumed that the driving force is "recoil pressure", and compared the estimated pressure value from this experiment with that shown in the references. The value estimated by the relationship between pressure and momentum was 1.3 MPa, which was close to that reported in the past.
Glass nanofibers are prospective material, because they have the potential to function as biomedical tissues, optical components, or catalysts. Now, precise control of synthesis method is necessary for a variety of glass nanofiber applications. We found that glass nanofibers were generated from the back surface of a substrate during a drilling experiment using a nanosecond pulsed UV laser. In this report, we investigated the generation process. To understand the process, we set up an optical system for generating nanofibers, which is capable of moving a sample linearly using an XY stage, and monitored around the laser spot using a CCD camera. A non-alkaline, thin glass substrate was irradiated with a laser beam of wavelength 355 nm and pulse width 40 ns. As a result, when the scanning speed and focusing position were favorable, glass nanofibers were generated. According to the in situ observation, microparticles were found on the tip of the nanofibers. Also, the glass substrate was modified in a wider range compared with the laser spot size. Thus, we considered that glass nanofibers were generated when the particles were ejected resulting from local heating. Additionally, glass nanofibers could be generated in combination with a galvano scanning system. The generation of glass nanofibers from the back surface of a substrate is advantageous in terms of their collection owing to the reduced interaction with the laser beam.