Phys.org March 16, 2020
If you irradiate pure germanium with a short laser pulse, it takes several microseconds before the electrical charge in the semiconductor disappears. Only then can the crystals absorb the next laser pulse. Gallium-arsenide crystals only deliver relatively narrowband terahertz pulses and thus a restricted frequency range. Researchers in Germany used gold implanted germanium to present ultrabroadband (extending up to 70 THz) THz emission that is compatible with mode-locked fibre lasers operating at wavelengths of 1.1 and 1.55 μm with pulse repetition rates of 10 and 20 MHz, respectively. This result opens the possibility for the development of compact THz photonic devices operating up to multi-THz frequencies that are compatible with Si CMOS technology. The research could lead to applications in medicine and environmental technology, sensors to trace certain gases in the atmosphere by means of their terahertz spectrum…read more. Open Access TECHNICAL ARTICLEÂ
If a gallium-arsenide crystal is irradiated with short laser pulses, charge carriers are formed. These charges are accelerated by applying a voltage which enforces the generation of a terahertz wave. Credit: HZDR/Juniks