Abstract
Most glasses are typically transparent to laser irradiation at near-infrared wavelengths. However, when a near-infrared femtosecond laser beam is focused inside a transparent material, the intensity in the focal volume can become high enough (1014 W cm−2) to cause nonlinear absorption, avalanche ionisation and microplasma formation. If sufficient energy is deposited, permanent structural change can occur, leading to a change in refractive index. In this work, investigations were conducted on the use of femtosecond laser pulses at 775 nm wavelength to induce localised refractive index changes in aluminosilicate glass that function as optical waveguides. The effects of laser pulse energy, writing speed and number of scans on the magnitude of the resultant refractive index change and dimensions of the modified structures were studied. The fabrication of potential waveguide devices was investigated and characterised.Most glasses are typically transparent to laser irradiation at near-infrared wavelengths. However, when a near-infrared femtosecond laser beam is focused inside a transparent material, the intensity in the focal volume can become high enough (1014 W cm−2) to cause nonlinear absorption, avalanche ionisation and microplasma formation. If sufficient energy is deposited, permanent structural change can occur, leading to a change in refractive index. In this work, investigations were conducted on the use of femtosecond laser pulses at 775 nm wavelength to induce localised refractive index changes in aluminosilicate glass that function as optical waveguides. The effects of laser pulse energy, writing speed and number of scans on the magnitude of the resultant refractive index change and dimensions of the modified structures were studied. The fabrication of potential waveguide devices was investigated and characterised.
Published Version
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