| 1. |
- Riepl, J., et al.
(author)
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Field-resolved high-order nonlinearities in a free-running terahertz quantum cascade laser
- 2022
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In: CLEO : Science and Innovations, S and I 2022 - Science and Innovations, S and I 2022. - 9781557528209
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Conference paper (peer-reviewed)abstract
- Two-dimensional terahertz strong-field spectroscopy reveals wave-mixing processes up to eighth order in a free-running quantum cascade laser, unravelling its sub-cycle gain dynamics and nonlinearities in a regime of negative absorption.
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| 2. |
- Riepl, J, et al.
(author)
-
Field-resolved high-order sub- cycle nonlinearities in a terahertz semiconductor laser
- 2021
-
In: Light, science & applications. - : Springer Science and Business Media LLC. - 2047-7538. ; 10:1, s. 246-246
-
Journal article (peer-reviewed)abstract
- The exploitation of ultrafast electron dynamics in quantum cascade lasers (QCLs) holds enormous potential forintense, compact mode-locked terahertz (THz) sources, squeezed THz light, frequency mixers, and comb-basedmetrology systems. Yet the important sub-cycle dynamics have been notoriously difficult to access in operationalTHz QCLs. Here, we employ high-field THz pulses to perform the first ultrafast two-dimensional spectroscopy of afree-running THz QCL. Strong incoherent and coherent nonlinearities up to eight-wave mixing are detected belowand above the laser threshold. These data not only reveal extremely short gain recovery times of 2 ps at the laserthreshold, they also reflect the nonlinear polarization dynamics of the QCL laser transition for the first time, where wequantify the corresponding dephasing times between 0.9 and 1.5 ps with increasing bias currents. A density-matrixapproach reproducing the emergence of all nonlinearities and their ultrafast evolution, simultaneously, allows us tomap the coherently induced trajectory of the Bloch vector. The observed high-order multi-wave mixing nonlinearitiesbenefit from resonant enhancement in the absence of absorption losses and bear potential for a number of futureapplications, ranging from efficient intracavity frequency conversion, mode proliferation to passive mode locking.
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| 3. |
- Riepl, J., et al.
(author)
-
Sub-cycle high-order nonlinearities in a free-running terahertz semiconductor laser
- 2022
-
In: The International Conference on Ultrafast Phenomena (UP) 2022. - 9781557528209
-
Conference paper (peer-reviewed)abstract
- Field-resolved two-dimensional spectroscopy reveals the sub-cycle gain dynamics of a free-running terahertz quantum cascade laser and disentangles resonantly enhanced nonlinearities up to eight-wave mixing in a regime where gain replaces absorption.
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| 4. |
- Riepl, J., et al.
(author)
-
Sub-cycle high-order nonlinearities in a terahertz quantum cascade laser
- 2022
-
In: IRMMW-THz 2022 - 47th International Conference on Infrared, Millimeter and Terahertz Waves. - 2162-2027 .- 2162-2035. - 9781728194271 ; 2022-August
-
Conference paper (peer-reviewed)abstract
- Ultrafast electron dynamics in quantum cascade lasers hold enormous potential for the implementation of intense, compact mode-locked terahertz sources, squeezed terahertz light, frequency mixers, and comb-based metrology systems. Yet the important sub-cycle dynamics have been notoriously difficult to access in operational terahertz quantum cascade lasers. Here we show the first field-resolved two-dimensional terahertz spectroscopy of a free-running quantum cascade laser, revealing its sub-cycle gain dynamics and disentangling resonantly enhanced high-order nonlinearities up to eight-wave mixing in a regime of negative absorption.
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