Previously used methods often required Acousto-optic modulators, which are relatively expensive and have narrow bandwidths. They can also be difficult to fabricate in integrated photonics platforms.
Serrodyne modulation (i.e., using a sawtooth waveform to produce a linear phase chirp) is performed using an electro-optic phase modulator to provide the needed frequency shift.
This provides a pathway for comb generation and operation in a chip-scale package. This approach also reduces cost and complexity by reducing the number of components and fabrication steps.
This lowers the associated cost by eliminating the need for a series of fiber optic splitters and individual modulators. Given the strong common-mode nature of the comb generation and the reduction of overall fiber length and number of components, the associated noise is expected to be lower.