Periodic Reporting for period 1 - MIDLIFT (Mid-infrared laser system for high-throughput bioprinting by laser-induced forward-transfer)
Periodo di rendicontazione: 2019-10-01 al 2021-09-30
The MIDLIFT laser system was developed to provide nanosecond pulses with sufficient pulse energies and peak powers to enable the precision processing of biological materials—specifically for applications in bioprinting by mid-infrared laser-induced forward-transfer (LIFT). To overcome the limitations of previously demonstrated laser sources in this wavelength range, we proposed a master-oscillator power-amplifier (MOPA) approach: to combine a compact, gain-modulated GaSb-diode laser with a single-mode Erbium-doped fluoride fibre amplifier. In the final part of the project, it was planned to demonstrate the application of the new laser system for mid-infrared LIFT bioprinting.
At the end of the project a new nanosecond MOPA laser system operating at a wavelength of 2790nm was demonstrated. We achieved output pulse energies of 52.7µJ, pulse durations of 5.2ns and peak powers of more than 8kW at a repetition rate of 10kHz, from an Erbium-doped fluoride fibre amplifier with a nearly diffraction-limited output beam profile (M2 < 1.3).
To increase the output pulse energies of the MOPA system, we replaced the GaSb-diode laser with a bulk PPLN-OPO (optical parametric oscillator), pumped by a Nd:YAG laser with a repetition rate of 10kHz. While significantly less compact, the OPO-system provided higher seed pulse energies of 0.5µJ, shorter pulse durations of 5.2ns and enabled the optimisation of the laser wavelength. With this setup, we achieved the following laser parameters: pulse energies of 52.7µJ, pulse durations of 5.2ns repetition rate of 10kHz, and a laser wavelength of 2790nm. These laser parameters are suitable for biomaterial processing applications and LIFT-based bioprinting. The obtained results have been submitted to Optics Letters for publication.