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Two-photon polymerization with diode lasers emitting ultrashort pulses with high repetition rate
(2020)
In this Letter, we investigate the resolution of two-photon polymerization (2PP) with an amplified mode-locked external cavity diode laser with adjustable pulse length and a high repetition rate. The experimental results are analyzed with a newly developed 2PP model. Even with low pulse peak intensity, the produced structural dimensions are comparable to those generated by traditional 2PP laser sources. Thus, we show that a compact monolithic picosecond laser diode without amplification and with a repetition rate in the GHz regime can also be applied for 2PP. These results show the high application potential of compact mode-locked diode lasers for low-cost and compact 2PP systems.
In this Letter, the authors present the construction of three-dimensional microstructures by two-photon polymerisation induced by ultrashort pulses of a mode-locked diode laser. The ultrafast light source is based on a diode laser with segmented metallisation to realise a waveguide integrated saturable absorber. It is subsequently amplified and compressed resulting in ultrashort laser pulses of 440 fs length and average output power of 160 mW at a fundamental repetition rate of 383.1 MHz. These pulses are coupled into a customised two-photon polymerisation setup. A series of suspended lines were fabricated between support cuboids for testing the process behaviour. A 3D structure with complex features was polymerised to demonstrate the high potential for mode-locked diode lasers in the field of direct laser writing.