Gigabit free-space multi-level signal transmission with a mid-infrared quantum cascade laser operating at room temperature

Abstract

Gigabit free-space transmissions are experimentally demonstrated with a quantum cascaded laser (QCL) emitting at mid-wavelength infrared of 4.65 μm, and a commercial infrared photovoltaic detector. The QCL operating at room temperature is directly modulated using on-off keying and, for the first time, to the best of our knowledge, four- and eight-level pulse amplitude modulations (PAM-4, PAM-8). By applying pre- and post-digital equalizations, we achieve up to 3 Gbit/s line data rate in all three modulation configurations with a bit error rate performance of below the 7% overhead hard decision forward error correction limit of 3.8×10. The proposed transmission link also shows a stable operational performance in the lab environment.

Enhanced Chaotic Performance with Optically Injected Quantum Cascade Lasers

“…Further investigation will determine the influence of the injection rate, in order to characterize the influence on chaotic frequencies. The long-term purpose is to combine the QCL abilities for high-speed free-space communications [5] with chaos masking in order to achieve secure communications, as already tested in fibers for near-infrared laser diodes [6]. : Experimental time trace (a) and RF spectrum (b) corresponding to the maximum frequency we could achieve with optical injection.…”

Controlling the Likelihood of Extreme Pulses in a Quantum Cascade Laser with Optical Feedback and Bias Perturbation

“…We further unveil a method to produce controllable extreme pulses which is highly relevant for sensing applications [4]. Midinfrared QCLs are intersubband semiconductor lasers and their versatility make them candidates of choice for a wide range of free-space applications such as high-speed communications [5] or light detection and ranging (LIDAR) [6].…”

High frequency dynamics in quantum cascade lasers : a roadmap to free-space communications in the mid-infrared

“…The first tests were conducted shortly after the experimental proof-ofconcept of QCLs, and as soon as 2001, a Peltier-cooled device showed the possibility of a data transmission up to 300 MHz over several hundred meters at 9.3 µm [1]. Recent investigations showed the relevance of a similar transmission but at room temperature and 4.65 µm [2]. The versatility of this method, combined with the QCLs' potential for high speed modulation up to 10 GHz [3], demonstrates that these lasers are poised to be the cornerstone of very high speed free-space data transmissions.…”