Quantum-dot micropillars for parametric THz emission
| Autor: | Martin Kamp, Peter Uhd Jepsen, Silvia Mariani, Ivan Favero, Giuseppe Leo, Sara Ducci, Alessio Andronico, Carlo Sirtori, Tianwu Wang, Jean-Michel Gérard, Yanko Todorov, Julien Claudon |
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| Rok vydání: | 2013 |
| Předmět: |
Materials science
business.industry Terahertz radiation Physics::Optics 02 engineering and technology 021001 nanoscience & nanotechnology Laser 01 natural sciences law.invention 010309 optics Wavelength Optics Semiconductor Quantum dot law 0103 physical sciences Optoelectronics Whispering-gallery wave 0210 nano-technology business Lasing threshold Ground plane |
| DOI: | 10.1117/12.2009452 |
| Popis: | We report on the design, fabrication and optical investigation of AlGaAs microcavities for THz Difference Frequency Generation (DFG) between Whispering Gallery Modes (WGMs), where the pump and DFG wavelengths (λ ≈ 1.3 μm and λ ≈ 75-150 μm, respectively) lie on opposite sides of the Restrahlen band. For the pump modes, we demonstrate CW lasing of quantum-dot layers under electrical injection at room temperature. We control the number of lasing WGMs via vertical notches on the pillars sidewalls, providing a selection mechanism for funneling the power only to the modes contributing to DFG. In parallel with the optimization of the pump lasers and in order to validate design and material parameters before the DFG experiments, we have performed linear measurements on two sets of passive samples. For the telecom range, the micropillars have been integrated with waveguides for distributed coupling and characterized via transmission measurements. In the THz range we have measured reflectivity spectra on 2D arrays of identical cylinders. In both cases, we demonstrate a good agreement between experimental results and simulations. On a more speculative note, we numerically show that etching a hole along the pillar axis can facilitate phase matching, while single-lobe farfield pattern can be obtained for the THz mode by micro-structuring the metallic ground plane around the microcavity. Finally, we suggest a real-time fine-tuning mechanism for the forthcoming active devices. |
| Databáze: | OpenAIRE |
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