Controlling frequency-comb fast-gain devices through photonic lattice engineering

Objective

Optical Frequency Combs (OFCs), states of light with equally spaced and phase-locked frequencies, revolutionized metrology across a wide range of metrological applications. Current OFC sources are highly accurate but also bulky. Miniaturizing OFC sources to on-chip scale, small enough to be placed in your hand, will enable a second revolution with applications such as distributed pollution tracking, medical detection equipment, compact LIDARs and dense communication channels (DWDM). OFC devices supporting these applications require: (a) in-situ control over the spectrum with power management of ~90% for every spectral line (b) bandwidth of 10-15THz (c) power per line of ~3mW while maintaining wall plug efficiency of >20% In LIQUIDLAT I will develop on-chip OFC devices with (a)-(c), by taking a new approach and leveraging on the recently demonstrated, by me and coauthors, quantum walk comb: generate monolithic lasers with fast gain recovery and apply photonic lattice schemes, both in real and frequency spaces through inter-device coupling and modulation, for controllable, broadband and powerful OFCs. This method is general and can be implemented in other wavelengths. Unlike current on-chip OFC approaches, typically producing pulses, I will use the following elements: (1) fast gain recovery that forces quasi constant intensity and grants the light liquid properties, stabilizing on broadband and stable states (2) direct control over OFC expansion via modulation by radio-frequency sources (3) use topological photonic lattice schemes, both in real and frequency domains, to lock coherently many OFCs to a single powerful output. The study of liquid light dynamics in photonic lattices challenges our understanding of nonlinear dynamics and interaction in semiconductors. The outcome is the development of tools for broadband power-efficient OFC devices that support applications in environmental tracking or efficient data links that reduce the datacentre footprint.