WP1: Overall training and knowledge transfer.
During the project, the scientific aspect of training and knowledge transfer was focussed on broadening the scientific expertise of the Fellow in the multidisciplinary field of semiconductor lasers and THz technology via scientific training courses and training-through-research. Furthermore, to ensure the further development of additional competencies, the Fellow has been trained in project and financial management, writing of proposals, organisational skills, leadership, teaching and supervision, as well as networking. In the framework of this project, German language courses have been also attended by the Fellow with the goal of the easy social adaptation and integration into the host University and Germany.
WP2: Modelling and crystal design optimisation.
As the result of the study carried out, the following most important conclusions can be derived:
• The knowledge on the most suitable crystal material and design for efficient THz generation based on difference frequency generation in the spectral window between 0.8 and 3 THz has been developed.
• The model and design of nonlinear crystals for ultra-efficient THz generation was developed and tested. Test samples aimed at the model validating were suggested and were fabricated for further use in the experiments.
• Novel periodically poled ferroelectric and semiconductor crystals were examined on the basis of available literature data. The optimal parameters, including periodic poling of nonlinear crystals and slanting angles of crystals poling, have been carefully designed for the efficient frequency conversion in the 0.8 – 3 THz spectral region utilising a surface emitting phase-matching scheme. By the design of these two parameters, the THz emission wavelength can be set at an intended value. The novel model has provided good agreement with the previously designed crystals used in early experiments with Terahertz-External-Cavity Surface-Emitting Lasers (TECSELs).
Disseminations: Phys. Status Solidi RRL 14, 2000204 (2020); CLEO/Europe-EQEC-2019 CC-7.3 (2019); FGTC (2019); ICLO-2020 ThR3-27 (2020).
WP3: High-power semiconductor disk lasers. Work carried out:
• Modelling, design, implementation and characterisation of single- and dual-chip semiconductor disk laser cavity configurations.
• Development and experimental study of semiconductor disk lasers providing stable high-power dual-wavelength operation in near-IR region with high-quality beams.
• Development and experimental study of dual-wavelength semiconductor disk lasers providing tunable difference frequencies.
Disseminations: Optics Letters 44, 4000 (2019); Phys. Status Solidi RRL 14, 2000204 (2020); CLEO/Europe-EQEC-2019 CC-7.3 (2019); FGTC (2019); ICLO-2020 ThR3-24, ThR3-27 (2020).
WP4: Highly-efficient THz laser generation. Work carried out:
• Development and experimental study of THz-generating semiconductor disk laser sources utilising different nonlinear crystals.
• Optimisation of laser cavities and utilisation of multi-chip cavities for further scale-up of the emitted THz power.
• Experimental study of the operating characteristics of demonstrated THz-laser sources.
• Design and demonstration of novel operating regimes for broadly-tunable THz generation from semiconductor disk laser sources.
• Development and experimental study of compact, continuous-wave, room-temperature, tunable THz-generating laser sources with practical output power.
Disseminations: Optics Letters 44, 4000 (2019); Phys. Status Solidi RRL 14, 2000204 (2020); CLEO/Europe-EQEC-2019 CC-7.3 (2019); FGTC (2019); ICLO-2020 ThR3-24, ThR3-27 (2020).
WP5: Testing of THz laser systems. Work carried out:
• Development and testing of ultra-efficient and widely-tunable stabilised THz-emitting semiconductor disk lasers as laser tools for application in THz spectroscopy and biomedical imaging.
Disseminations: Optics Letters 44, 4000 (2019); Phys. Status Solidi RRL 14, 2000204 (2020); CLEO/Europe-EQEC-2019 CC-7.3 (2019); FGTC (2019); ICLO-2020 ThR3-24, ThR3-27 (2020).
