Periodic Reporting for period 1 - SELECT (SEmiconductor disk Lasers for EffiCient Terahertz generation)
Reporting period: 2019-01-01 to 2020-12-31
The Fellowship, entitled “SEmiconductor disk Lasers for EffiCient Terahertz generation” (SELECT) has successfully reached its primary goal of training a talented researcher, Dr. Ksenia Fedorova, through a research project in the fast-growing field of science, technology and industrial applications of THz-emitting semiconductor-based lasers. The success of the innovative multidisciplinary project has led to the development of stable, ultra-efficient, compact THz lasers for a number of applications ranging from spectroscopy and biomedical imaging to security screening and quality control.
The overall objectives of the project were: (i) Broadening of the Fellow’s expertise in semiconductor lasers and Terahertz (THz) technology with a focus on industrial applications; (ii) Development of novel models for optimum design of nonlinear crystals to meet power and wavelength goals; (iii) Design of advanced techniques for stable high-power dual-wavelength operation of semiconductor disk lasers; (iv) Development of the stable highly-efficient laser system generating THz radiation with practical output power; and (v) Applications of the laser systems in THz spectroscopy and biomedical imaging fields.
During the project duration excellent progress has been made: detailed numerical model for design of nonlinear crystals has been developed for ultra-efficient THz generation, stable high-power dual-colour semiconductor disk lasers operating in the near-IR region, as well as stabilised ultra-efficient THz-emitting lasers for application in THz spectroscopy and biomedical imaging, have been designed and demonstrated, and novel operating regimes for broadly-tunable THz generation have been identified. The obtained results are enormously encouraging and confirm the great potential of this technology to enable future development of stable, room-temperature, high-performance laser sources capable of generating THz radiation with practical output power for the range of scientific, industrial, and biomedical applications. The results achieved and laser prototypes developed during the SELECT project have shown that compact, room-temperature, highly-efficient THz laser sources could be made more readily available to both industry and society as a whole. This will certainly enhance EU scientific excellence.
The overall objectives of the project were: (i) Broadening of the Fellow’s expertise in semiconductor lasers and Terahertz (THz) technology with a focus on industrial applications; (ii) Development of novel models for optimum design of nonlinear crystals to meet power and wavelength goals; (iii) Design of advanced techniques for stable high-power dual-wavelength operation of semiconductor disk lasers; (iv) Development of the stable highly-efficient laser system generating THz radiation with practical output power; and (v) Applications of the laser systems in THz spectroscopy and biomedical imaging fields.
During the project duration excellent progress has been made: detailed numerical model for design of nonlinear crystals has been developed for ultra-efficient THz generation, stable high-power dual-colour semiconductor disk lasers operating in the near-IR region, as well as stabilised ultra-efficient THz-emitting lasers for application in THz spectroscopy and biomedical imaging, have been designed and demonstrated, and novel operating regimes for broadly-tunable THz generation have been identified. The obtained results are enormously encouraging and confirm the great potential of this technology to enable future development of stable, room-temperature, high-performance laser sources capable of generating THz radiation with practical output power for the range of scientific, industrial, and biomedical applications. The results achieved and laser prototypes developed during the SELECT project have shown that compact, room-temperature, highly-efficient THz laser sources could be made more readily available to both industry and society as a whole. This will certainly enhance EU scientific excellence.
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).
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).
Considerable progress in developing new efficient, compact, room-temperature THz laser sources has been made within the SELECT project. This has resulted in a significant body of knowledge in terms of nonlinear crystal modelling and laser system design. It has led to the realisation of THz laser devices that may now find application in a number of practical and scientific areas of high social impact, ranging from security screening and quality control to spectroscopy and biomedical imaging.
In addition to the THz-laser systems initially envisaged by the consortium, beyond the state-of-the-art widely-tunable THz-generating semiconductor disk laser sources have been realised. This offers the prospect of end-users being able to tune the THz frequency of such a room-temperature laser device to suit the needs of their particular applications. The performance achieved so far has led to a strong case for further development work, which is due to continue beyond the end of this project and which shall bridge the gap between academic research and industry uptake.
In addition to the THz-laser systems initially envisaged by the consortium, beyond the state-of-the-art widely-tunable THz-generating semiconductor disk laser sources have been realised. This offers the prospect of end-users being able to tune the THz frequency of such a room-temperature laser device to suit the needs of their particular applications. The performance achieved so far has led to a strong case for further development work, which is due to continue beyond the end of this project and which shall bridge the gap between academic research and industry uptake.