Single-Frequency 2 μm GaSb-Based VECSEL for Quantum-Frequency-Converter Pumping

Narrow-linewidth, tunable laser sources in the 2 – 3 μm wavelength range are of special interest for a range of applications such as gas analysis, remote sensing, LIDAR, optical free-space communication, laser seeding as well as for quantum optical experiments. In the latter field, the quantum frequency conversion (QFC) of single photons to the telecom band at 1550 nm is an emerging technology in order to enable long-haul quantum optical communication via the existing fiber-based networks. This conversion process is necessary, as the best and most widely used single photon sources or Q-Bit systems have wavelengths in the visible to near infrared spectral range.