| Abstract [eng] |
Direct Writing of Optical Waveguides with Femtosecond Pulses and Integration into Microfluidic Structures -Tomas Baravykas Ultrashort pulse laser systems are widely used in material science, metrology, medicine, telecommunication, energetics, and so forth. Due to the demand of a fast easy solution to measure solutions in microfluidics a optofluidic structure was developed, which can easily be integrated into microchannels to measure these fluids. Fused silica is very suitable for applications in microfluidic, microoptics since the components can be written in this glass using a femtosecond laser. In this study using a femtosecond laser and direct writing technologies in fused silica we formed waveguides with different sized wells. The experiments were carried out using a femtosecond "Pharos" laser manufactured by Light Conversion. A objective with 0.42 NA was used to focus the beam onto the sample glass, translation of the sample was done with Aerotech translation tables. Measurements of light transmission through formed waveguides were done, and spectrums were analyzed when light traveled across air, water and rhodamine 6G gaps. The formed waveguides output a Gaussian profile beam, which is especially true for wider gap wells. When comparing the amount of light that is transmitted through the waveguide when there are no wells, to when there are air gaps there is about 10 times less light transmitted, when there is water in the gaps, the difference is about 2-3 times. 25 to 200 um wide gaps transmit about the same amount of light. Rhodamine 6G exhibits absorption up to 610 nm, but our measured spectrums show total absorption up to 550-575 nm, this can be attributed to the collection of additional components that come due to the total internal refraction from the samples upper and lower surfaces, in addition slightly tweaking the position of the optical fiber makes the peaks move towards different wavelengths. Measured spectrum intensity does not relate to the wideness of the gaps, a reduced intensity of e2 is expected if you increase the width of the gap by two, but this was not the case, the reason for this is because rhodamine 6G absorbs most of the light in the 450-550 nm range after a few micrometers of material. |
