Abstract-Optically-pumped continuous-wave terahertz sources

Philipp Latzel ; Fabio Pavanello ; Emilien Peytavit ; Mohammed Zaknoune ;Guillaume Ducournau ; Xavier Wallart ; Jean-François Lampin

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2110839

Philipp Latzel, Fabio Pavanello, Emilien Peytavit, Mohammed Zaknoune, Guillaume Ducournau, Xavier Wallart, Jean-François Lampin

Institut d'Electronique de Microélectronique et de Nanotechnologie (France)

Proc. SPIE 9370, Quantum Sensing and Nanophotonic Devices XII, 937008 (February 8, 2015); doi:10.1117/12.2080756

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Recently we have improved the efficiency and the output power of our optically pumped continuous-wave THz sources. These sources are based on the beating of two laser lines in a wide bandwidth photodetector. Its intrinsic nonlinear behaviour is used to produce a beatnote at the frequency difference between the two laser lines (photomixing). These photomixers are continuously tunable THz sources working at room temperature. We have developed two kinds of photomixers: GaAs-based for 0.8 μm pumping and InP-based for 1.5 μm pumping. On GaAs the best results has been obtained thanks to low-temperature-grown GaAs (LTG-GaAs) photoconductors (PC). Efficiency and power were optimized by designing a new type of thin PC placed in a Fabry-Pérot resonator. The high impedance of the PC is a wellknown limitation of this device but with our approach it was possible to reduce its impedance by a factor 100. Moreover by designing an impedance matching network it was possible to obtain 1.8 mW at 252 GHz with a total efficiency of 0.5 %. On InP the best results are obtained with uni-travelling-carrier photodiodes (UTC-PD). The device was improved by designing a new heterostructure and new semi-transparent contacts with sub-wavelength apertures. The active layer was also bonded to a silicon substrate thanks to metal thermocompression. It is demonstrated that with this approach it is possible to obtain a power of 0.7 mW at 300 GHz with a total efficiency of 0.7 %. More generally the efficiency of optically pumped terahertz sources will be discussed. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.