Micromachining of glass with nanosecond Nd:YAG and femtosecond Ti:Sapphire laser pulses

Micro-machining of glass is important for fabricating many optical elements (filters, waveguides and microlenses), but the process is challenging due to the brittleness of glass. The use of short and ultrashort pulsed lasers operating in the near infrared spectral regions for such applications is discussed in this work. A one-dimensional model is developed to predict the machining results based on material properties such as the thermalization time, bond strength and absorption coefficient. The model is used to predict the ablation rate for micro-machining soda lime glass with fs Ti:Sapphire laser pulses. lt may not be applicable to the case of micromachining with relatively long ns, such as 50 ns or higher laser pulses because the physical effects of heating, melting and vaporization are not considered. Experimental results show that the micromachining of glass is possible with ultrashort laser pulses in the near IR region. Short (80 ns FWHM) Nd:YAG laser pulses are found to be unsuitable for micro-machining glass due to thermal stress-induced cracking. Crack-free lines and channels were created with ultrashort Ti:Sapphire laser pulses (150 fs) at lambda = 775 nm, and optical microscopy and atomic force microscopy (AFM) revealed no molten material in the ablated region.