We report results of a systematic study of the morphology of laser-written structures within transparent media like fused silica, borosilicate glass (BK7), and polymethylmethylacrylate (PMMA) using a high-energy, 5.1 MHz repetition rate, femtosecond laser oscillator. Depending on experimental conditions, both smooth channels as well as dot patterns can be laser-written. The periodicity of the written dots is readily controlled by the energy dose, a single parameter that encompasses laser energy, translation speed at fixed repetition rate, and focusing conditions. We discover the importance of the direction in which laser-writing is carried out: the periodicity of the dot patterns written at fixed energy dose but with opposite writing directions is significantly different. In PMMA, extremely large rod-like structures (∼200 μm) are observed whose formation is also dependent on writing direction. We quantify guidance of 632 nm and 830 nm light in structures written in BK7.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry