The ever-increasing demand for wireless communications has created a need for extremely wideband radio transmitters that can deliver multi-giga-bit-per-second data rates to individual users. A promising approach that can enable these high data rates and even future faster tera-bit-per-second (Tbps) data rate is the use of the millimeter-wave (mm-wave) spectrum (30 to 300 GHz) which readily provides a vast amount of bandwidth. Cellular networks operating at mm-wave frequencies will increase the required base station bandwidth significantly, but they will also decrease the size of each cell dramatically due to the large path loss and atmospheric absorption at these frequencies. As a result, installing a base station on every light pole may become necessary to guarantee coverage in an urban environment. This scenario creates many technical challenges since the baseband rack-mount hardware equipment cannot be placed adjacent to each antenna in this case. To address this, solutions are needed that allow for dense deployment of compact mm-wave base stations with Tbps-level throughput whose complex communication equipment can be placed away from the antenna itself. Compared to pure electronic solutions, photonic technologies offer many technical advantages to realize such wideband systems. However, traditional photonic approaches are not scalable and suffer from large insertion loss and large footprint when cascading discrete components. This project will address these challenges by a joint multidisciplinary effort that leverages recent developments in nonlinear optics, integrated photonics, and wideband integrated antennas to enable a compact platform that can provide a vast array of wireless channels with over 1 Tbps data capacity.
This project aims to develop a new paradigm for chip-scale Tbps wireless systems. The approach is based on optical dual-microresonators with ultra-high quality factor, where mode-locked femtosecond soliton pulses are generated through the balance between cavity dispersion and Kerr nonlinearity to create arrays of stable optical carriers. Filtering, data modulation, and multiplexing will be accomplished in the optical domain through ring resonators, heterogeneously integrated high-bitrate modulators, and arrayed waveguide gratings. Conversion into the mm-wave frequencies will be achieved by heterodyne detection in ultra-wideband photodetectors, which will be co-designed with integrated antennas to ensure efficient radiation into free space. This effort is expected to advance not only the performance of individual components and circuits, but also the miniaturization and applicability of integrated photonic-electronic technologies to push the state-of-the-art for mm-wave wireless communications. The fact that all key components will be integrated on a single chip will pave the way toward manufacturable large-scale mm-wave photonic integrated circuits with small size, light weight, and low power, which will also benefit other applications in sensing and imaging. The research will allow in-depth studies of the potential benefits, trade-offs, and limits of photonically driven high-frequency technologies.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.