Monolithically Integrated Mode-Locked Laser for Optical Signal Processing Applications

RF photonic principles have been successfully utilized in the community to advance analog-to-digital converter (ADC) performance. For some applications, photonic ADCs fill an important and continuing need. However, photonic ADCs that capture more bandwidth also produce more data. The increased data stream itself gives rise to a data management and computer processing challenge that undesirably increases system size weight and power (SWaP). Another approach is to use photonics in a compressive sensing (CS) architecture. Photonic CS similarly captures signals over increased bandwidths, but uses optical pre-processing to drastically compress the data volume and produce only the information of interest. By reducing the output data stream, photonic CS systems are suitable for SWaP constrained applications that preclude photonic ADCs.  Current efforts to miniaturize CS systems are underway, but the pulse source still needs to be addressed. To provide system benefit, the source developed in this effort must produce a pulse train having a low repetition rate between 10 to 100 MHz. Such low rep-rate mode-locked laser (MLL) sources are commonly available in fiber and free space platforms, where long cavities are easily realized such as in Er:fiber and Ti:sapphire lasers, respectively, however they suffer from large SWaP which limit their use on Naval air platforms. In this program, Freedom Photonics will investigate and develop monolithic and hybrid MLL architectures that satisfy the demanding requirements for optical signal processing applications and enable advanced photonic CS systems.