FOLKLORE

In many microwave or optical communication applications, pulsed laser or frequency comb sources play an essential role in radio or optical signal processing systems. A much desired but cumbersome feature to implement is flexibility. Flexibility in the pulse repetition rate corresponds to a comb with a dynamically controllable free spectral range (FSR). It allows simpler system architecture and more compact photonic integrated circuits. Folklor introduces a novel concept of semiconductor mode-locked laser (MLL), inherently flexible, based on a resonator allowing a large, continuous or fractional, change of the FSR, hence the repetition rate changes without any mechanical moving part. The physical mechanism is rooted in spatial hole burning and phase-amplitude coupling. The laser cavity contains a tapered grating which was designed to allow several longitudinal modes which can be locked. We have theoretically and experimentally demonstrated the flexibility of such lasers. The main challenges Folklore ambitions to take up are: 1) extend the locked modes number (>8) & the beat-note values (up to 40GHz); 2) demonstrate optical injection locking and perform a frequency-agile optical clock recovery; 3) implement the InAs quantum dash on Si wafer- or die-bonding technology and design & demonstrate new flexible MLL. Folklore consortium will deliver two sets of demonstrations: 1/ Microwave oscillator applications: using an electro-optic feedback loop, we will demonstrate & assess an agile microwave optoelectronic oscillator (OEO) without any tuneable radiofrequency filter. 2/ 6G applications: we will demonstrate & assess a coherent WDM transmitter (Tx) subsystem, with at least two spectral separations; we will also demonstrate clock recovery, from at least two distinct bit-rates NRZ-format signals. Folklore is structured around three technical work packages: design and modelling (WP1), fabrication (WP2), tests & characterization (WP3). A 4th WP contains project valorisation.