Browsing by Author "Prather, Dennis W."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Array-Beamspace Mapping for Planar Two-Dimensional Beam-Forming(IEEE Access, 2023-07-21) Beardell, William L.; Murakowski, Janusz; Schneider, Garrett J.; Prather, Dennis W.As sixth-generation (6G) communication systems manifest at carrier frequencies well into the millimeter-wave (mmW) spectrum, the ability of conventional digital beamforming techniques to handle the beam-bandwidth product is increasingly stressed. Microwave photonic beamforming has been presented as a solution to this problem by up-converting a sampled RF field distribution to an optical carrier for analog beam-space processing, but to date has relied upon fiber arrays with the same dimensionality as the RF array, i.e., a two-dimensional RF array requires a two-dimensional fiber array and a three-dimensional optical processor to perform the Fourier transform required for two-dimensional beamforming. To address this problem, we present an approach to photonic mmW beamforming wherein two-dimensional phase information is preserved through a one-dimensional Fourier transform leveraging grating lobes in the array response. This approach carries several benefits, primarily as an enabler for leveraging photonic integrated circuits for RF-photonic beamforming, carrying with it a footprint reduction of more than ten thousand times. Furthermore, beamforming efficiency is increased for sources near the limits of the RF field-of-view; improvements to throughput power in such cases are as much as double. Theory, simulations, and experimental results in the form of images and videos are presented to validate the approach for a nineteen-element hexagonally-distributed phased array.Item Compact thin film lithium niobate folded intensity modulator using a waveguide crossing(Optics Express, 2022-03-04) Nelan, Sean; Mercante, Andrew; Hurley, Cooper; Shi, Shouyuan; Yao, Peng; Shopp, Benjamin; Prather, Dennis W.A small footprint, low voltage and wide bandwidth electro-optic modulator is critical for applications ranging from optical communications to analog photonic links, and the integration of thin-film lithium niobate with photonic integrated circuit (PIC) compatible materials remains paramount. Here, a hybrid silicon nitride and lithium niobate folded electro-optic Mach Zehnder modulator (MZM) which incorporates a waveguide crossing and 3 dB multimode interference (MMI) couplers for splitting and combining light is reported. This modulator has an effective interaction region length of 10 mm and shows a DC half wave voltage of roughly 4.0 V, or a modulation efficiency (Vπ ·L) of roughly 4 V·cm. Furthermore, the device demonstrates a power extinction ratio of roughly 23 dB and shows .08 dB/GHz optical sideband power roll-off with index matching fluid up to 110 GHz, with a 3-dB bandwidth of 37.5 GHz.Item Microwave Photonic Direction-Finding Spectrometer(Journal of Lightwave Technology, 2023-05-15) Beardell, William L.; Ryan, Conor J.; Schneider, Garrett J.; Murakowski, Janusz; Prather, Dennis W.In this paper, we propose an architecture wherein the radio-frequency (RF) field at the antenna array is up-converted to an optical carrier and passed through an array of optical fibers, after which an analog Fourier transform is taken in a free-space optical processor. Through the use of multiple temporal dispersion projections, implemented through varied-length optical fiber segments, the locations of RF sources in three-dimensional space spanning angle-of-arrival (AoA) and instantaneous frequency may be determined on a millisecond time scale using commercial computing hardware after detection by a charge-coupled device (CCD) camera. We present a mathematical formulation of the problem, followed by simulated and experimental results showing three-dimensional spatial-spectral localization through the solution to a system of equations brought forth through the use of Fourier optics to process the RF field.Item Phase modulation using a titanium dioxide strip on lithium niobate(Optical Materials Express, 2022-08-01) Zhu, Xiaofeng; Nelan, Sean; Mercante, Andrew J.; Shopp, Benjamin; Yao, Peng; Shi, Shouyuan; Prather, Dennis W.In this manuscript, we demonstrate the first phase modulator using titanium dioxide as a strip loaded waveguide on thin-film lithium niobate. The amorphous titanium dioxide was fabricated using RF reactive sputtering followed by a dielectric lift-off process. Two gold electrodes were deposited next to the waveguide by using the same process. This process eliminates the need for plasma etching or high-temperature vapor deposition methods, opening the door to fabrication on sensitive material systems. A propagation loss of 0.156 dB/mm and V𝜋 of 3.2 V at 1550 nm were experimentally measured and reported.Item Ultrawideband Modular RF Frontend Development for Photonically Enabled Imaging Receiver(IEEE Microwave and Wireless Technology Letters, 2024-05-07) Shi, Shouyuan; Wang, Fuquan; Abney, Jeremy; Aranda, Zion D.; Schneider, Garrett J.; Schuetz, Christopher; Harrity, Charles; Shreve, Kevin; Zablocki, Mathew; Dontamsetti, Samhit; Lawrence, Robert; Prather, Dennis W.This letter presents a modular-based RF frontend developed for photonically enabled phased-array systems that are capable of ultrawideband (UWB) operation from microwave to millimeter-wave (mmW) frequencies. The 1×8 modular architecture with integrated antennas, low-noise amplifiers (LNAs), and electrooptic modulators is reconfigurable and scalable to form 2-D phased arrays of any size. The developed phased-array system demonstrates the ability to process multiple wide-bandwidth RF beams simultaneously, yielding unmatched beam-bandwidth product (BBP).