The generation of squeezed states of light lies at the heart of modern photonics-based quantum information technologies. Traditionally, optical nonlinear interactions have been employed to produce squeezed states. However, the harnessing of electrically pumped semiconductor lasers offers distinctive paradigms to achieve enhanced squeezing performance for real-world applications. We present the first evidence that quantum dot lasers enable the realization of broadband amplitude-squeezed states at room temperature across a wide frequency range, spanning from 3 GHz to 12 GHz. Our findings are corroborated by a stochastic simulation in agreement with the experimental data. Published by the American Physical Society 2024
In article number 1803849, Rui Yang, Xin Guo, and co-workers describe the use of a volatile W/WO3/PEDOT:PSS/Pt memristive device to emulate neuronal functions. Taking advantage of the fast volatility, the device successfully emulates the local graded potential of a biological neuron, and a circuit in which these memristive devices are the key elements physically demonstrates the functions of leaky integrate-and-fire. The migration of protons and electrons in WO3 is similar to the transport of Na+ and K+ in the neuronal membrane, contributing to the successful realization of the Hodgkin–Huxley model in neuroscience.
The integration of optical functions on a microelectronic chip brings many innovative perspectives, along with the possibility to enhance the performances of photonic integrated circuits (PIC). Owing to the delta-like density of states, quantum dot lasers (QD) directly grown on silicon are very promising for achieving low-cost transmitters with high thermal stability and large insensitivity to optical reflections. This paper investigates the dynamical and nonlinear properties of silicon based QD lasers through the prism of the linewidth broadening factor (i.e. the so-called α-factor) and the optical feedback dynamics. Results demonstrate that InAs/GaAs p-doped QD lasers epitaxially grown on silicon exhibit very low α-factors, which directly transform into an ultra-large resistance against optical feedback. As opposed to what is observed in heterogeneously integrated quantum well (QW) lasers, no chaotic state occurs owing to the high level of QD size uniformity resulting in a near zero α-factor. Considering these results, this study suggests that QD lasers made with direct epitaxial growth is a powerful solution for integration into silicon CMOS technology, which requires both high thermal stability and feedback resistant lasers.
In this work, the sensitivity to external optical feedback of two different InAs/GaAs QD Fabry-Perot (FP) lasers is investigated under long cavity regime. The first, which has a 1.5 mm-long cavity, emits on the GS while the second one, which is 1 mm long, radiates solely on the ES transition. The results indicate that for the same bias level, the ES laser presents a larger sensitivity to external feedback, the critical level being under 1% versus above 9% for the GS laser. In particular, the ES laser exhibits a route to chaos such that the first destabilization occurs for a lower feedback strength than for the GS laser.
This work investigates the dynamic and nonlinear properties of quantum dot (QD) lasers directly grown on silicon with a view to isolator-free applications. Among them, the chirp parameter, also named the αH factor, is featured through a thermally insensitive method analyzing the residual side-mode dynamics under optical injection locking. The αH at threshold is found as low as 0.32. Then, the nonlinear gain is investigated from the gain compression factor viewpoint. The latter is found higher for epitaxial QD lasers on silicon than that in heterogeneously integrated quantum well (QW) devices on silicon. Despite that, the power dependence of the αH does not lead to a large increase of the chirp coefficient above the laser’s threshold at higher bias. This effect is confirmed from an analytical model and attributed to the strong lasing emission of the ground-state transition, which transforms into a critical feedback level as high as −6.5 dB, which is ∼19 dB higher than a comparable QW laser. Finally, the intensity noise analysis confirms that QD lasers are overdamped oscillators with damping frequencies as large as 33 GHz. Altogether, these features contribute to fundamentally enhancing the reflection insensitivity of the epitaxial QD lasers. This last feature is unveiled by the 10 Gbit/s error-free high-speed transmission experiments. Overall, we believe that this work is of paramount importance for future isolator-free photonics technologies and cost-efficient high-speed transmission systems.
