Schematic of USRN compressor system. The system has separate dispersive and nonlinear stages. For spectral compression, pulses enter the dispersive (DS) stage first before the nonlinear (NS), while pulses for temporal compression enter NS before DS. Credit: SUTDCargo trains have limited space. The cargo size and train capacity limit the amount of cargo that can go onboard. Similar to the above, the time it takes for an optical signal to transmit data limits how much data can be carried. In a process called optical time division multiplexing, shorter signals can squeeze more data into a short time period. Researchers in photonics have recently been able to squeeze light into time by an impressive factor of 11. The temporal compression system was developed to allow for an equivalent increase in bits transmitted by light through a fiber optic network.The same system can also squeeze the frequency or wavelength of light by using analogous dualities in time and space. A light source with red, yellow, and blue colors will have its spectrum compressed so that it only has yellow light. When wavelength division multiplexing (WDM) is used, the optical signal's color limit limits how much data can be carried through a fiber optic network. This ability to spectrally squeeze light may allow for higher spectral densities in light propagating through a particular medium.This work was published in Light: Science and Applications, June 18th 2021. It was a collaboration between researchers from the Singapore University of Technology and Design, A*STAR Institute of Microelectronics and Massachusetts Institute of Technology. The compressor system is much smaller than benchtop compressors that are used to generate short pulses for ultrafast optical signal processing.Two-stage design with a dispersive and strongly nonlinear components made it possible to achieve high compression.We could achieve strong compression in both frequency and time by balancing the contributions of the nonlinear and dispersive stages. The strongest temporal compression ever demonstrated on a chip is the one that has been shown. "The spectral compression was also the first such demonstration on a chip," Dr. Ju Won Choi said, the research fellow who participated in this project.Strong compression could be enabled on such a small footprint device to enable low-cost deployment of short pulses required in telecommunications and precision manufacturing."The on-chip integrated system that can both high temporal compression and spectral compression has been demonstrated allows for flexibility in manipulating optical pulses. This is a significant capability given the increasing burden placed on high-speed communications. Data center, telecommunications, and 5G industries will need more capacity. Approaches such as these will help in this drive toward faster optical communication networks." Associate Professor Dawn Tan, SUTD, was the principal investigator.Learn more Obtaining UV nonlinearity using a wide-bandgap semiconductor waveguideInformation: Ju Won Choi et. al., High spectrotemporal compression on a CMOS-chip that is nonlinear, Light: Science & Applications (2021). Information from the Journal: Light Science & Applications Ju Won Choi et. al. High spectrotemporal compression on a CMOS-chip that is nonlinear, (2021). DOI: 10.1038/s41377-21-00572-z
