2020 年 86 巻 1 号 p. 113-119
A photonic nanojet (PNJ) is a fine high-intensity light beam that is generated at the backside of a dielectric microsphere irradiated a laser light. A PNJ has a smaller beam diameter than the incident wavelength. Moreover, a PNJ can propagate a longer distance than 1 μm while maintaining a high intensity with minimal divergence. We propose a laser micro machining method using a PNJ. In this paper, hole machining experiments and finite-difference time-domain simulations were conducted to investigate the fundamental characteristics of laser micro machining using a PNJ by controlling PNJ position in the propagation direction. Hole machining experiments showed that a PNJ is suitable for micro/nano machining. The simulations also showed that nanometer scale machining is possible even though the position of PNJ changes by 1 μm in the propagation direction due to the minimal divergence beam.