Hybrid Chip-Scale Frequency Combs Combining III-V Quantum-Dash Mode-Locked Lasers and High-Q Si3N4 Microresonators – HybridCombs

Chip-scale optical frequency comb generators have the potential to revolutionize many applications in science and industry, comprising high-throughput optical communications using massively parallel wavelength-division multiplexing (WDM), ultra-fast optical ranging and LiDAR, as well as ultrabroadband photonic-electronic signal processing. However, while laboratory experiments have shown the extraordinary potential of such schemes, the practical viability in real applications is still limited by fundamental deficiencies of currently available comb sources. Specifically, there is at present no comb generator concept that can provide broadband smooth spectra with low optical linewidth and phase noise, while offering simple and power-efficient operation in a chip-scale package.
HybridCombs aims at overcoming this lack by exploring, designing, implementing, and experimentally demonstrating a novel class of chip-scale frequency comb sources, that combine the distinct advantages of soliton Kerr combs and with those of mode-locked lasers based on low dimensional III-V compounds. On a technological level, our approach relies on hybrid multi-chip modules that combine quantum-dash mode-locked laser diodes (QD-MLLD) or QD-based reflective semiconductor optical amplifiers (QD-RSOA) with specifically co-designed linear and nonlinear Si3N4-based photonic circuits, thereby merging the complementary strengths of the two integration platforms. Within the project, we shall establish a detailed theoretical framework that quantitatively describes multi-tone injection locking of QD-MLLD or QD-RSOA by optically linear and nonlinear Si3N4 feedback circuits, design and realize the underlying III-V and Si3N4 devices, and combine them by means of advanced 3D-printed optical coupling elements. Based on these foundations, we will realize hybrid chip-scale comb sources with unprecedented performance parameters in terms of linewidth and power consumption and experimentally demonstrate their practical viability in selected applications such as massively parallel optical communications, high-precision optical ranging, or ultra-broadband photonic-electronic signal processing. The project consortium consists of internationally leading teams from France and Germany, that are in a perfect position to tackle the proposed research at the international forefront of science. We expect that successful demonstration of the envisaged comb sources will be of transformative impact on a series of industrial and scientific applications that can be efficiently addressed by the partners within the consortium.