[19p-231B-1~9] 4.7 Laser Material Processing and Manipulation

▲ [19p-231B-6] Influence of heat accumulation on femtosecond laser written birefringence inside silica glass

〇Masaaki Sakakura¹、Lei Wang¹、Dambe Douti¹、Dmitrii Kliukin¹、Peter G Kazansky¹ (1.University of Southampton)

キーワード：femtosecond laser processing, glass, heat accumulation

Femtosecond (fs) laser direct writing of birefringent structures in silica has been used to generate unique optical devices that can manipulate and characterize the spatial polarization properties of light. Recently, a number of high power fs laser sources at high repetition rates (1-100 MHz) have become commercially available. As a result the use of high repetition rate fs laser sources has become a popular choice to increase the throughput of direct fs laser writing systems.
However, the throughput is often limited by the accumulation of thermal energy in the illuminated materials, which becomes dominant when the time between successive laser pulses becomes comparable to the thermal diffusion time. An investigation of heat accumulation effects and the mechanism behind these is important to fully understand the limitations arising from the use of higher repetition rates and to help identify potential techniques that circumvent these limitations. This study reports on the investigation of the influence of repetition rate of fs laser induced birefringence inside silica and discuss the relation between the magnitude of the induced birefringence and the repetition rate, supported by simulations of thermal diffusion.