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Theran Suárez, Larry R.

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    Low power receiver front-end design for millimeter waves spectrum monitoring
    (2024-12-12) Theran Suárez, Larry R.; Rodríguez Solís, Rafael A.; College of Engineering; Medina Sánchez, Rafael H.; Ducoudray Acevedo, Gladys O.; León Colón, Leyda V.; Department of Electrical and Computer Engineering; Lysenko, Sergiy
    Technological advancements in the last decade have significantly increased bandwidth requirements in wireless communications, leading to a scarcity of radio spectrum [1]. This has heightened the importance of spectrum monitoring for managing spectrum use, particularly in congested lower frequency bands associated with local wireless networks, IoT, and smart city devices. Commercial systems for spectrum monitoring, especially at millimeter-wave frequencies, are expensive and consume substantial power. The mm-wave frequency bands are increasingly vital for applications such as 6G communications [2], radio astronomy [3], satellite remote sensing [4], and atmospheric sensing [5]. Current commercial mm-wave spectrum monitoring solutions are bulky and costly [6], necessitating the development of compact, low-power, and cost-effective spectrum and radio frequency interference (RFI) monitors. This work aims to design and develop an analog front-end for a low size, weight, power, and cost (SWaP-C) spectrum monitor. The proposed system includes a low-noise amplifier, a self-oscillating mixer at mm-wave frequencies. The receiver targets interference monitoring to enhance scientific radio observations, focusing on the 20-30 GHz. These frequencies are used for atmospheric profiling in the Radiometrics 3000A radiometer [7], which will be deployed at UPRM as part of an RFI monitoring testbed for the Center CARSE.
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    Development of angle-resolved light scattering system and computation techniques for ultrafast surface spectroscopy
    (2019-07-09) Theran Suárez, Larry R.; Lysenko, Sergiy; College of Arts and Sciences - Sciences; Fernández, Félix E.; Jiménez González, Héctor J.; Department of Physics; Rodríguez Martínez, Manuel
    This work focused on the development of a time- and angle-resolved hemispherical elastic light scattering (tr-ARHELS) optical apparatus, which was applied to monitor the phase transition and complex pathways of photoinduced nonlinear optical dynamics in V3O5 thin film. This setup enabled us to perform spectral imaging of optical diffraction and ultrafast diffraction conoscopy with femtosecond resolution. The investigation of ultrafast photoinduced processes in phase-change materials is of special interest since methods of ultrafast spectroscopy can potentially track electron and phonon lattice dynamics separately and detect small structural variations on the surface of thin films. To achieve higher flexibility in optical measurements, a non-collinear optical parametric amplifier was built to generate broadband pulses with variable wavelengths by using an optical parametric amplification process. Since our main goal was to study short events, a pulse compressor was built in order compress the pulse from 130 to 20 femtoseconds. All the components of the tr-ARHELS setup such as charge-couple device (CCD) camera, translational stages, stepper motors, and photo detector, were integrated and programmed. Using a vacuum system and a refrigerator with a cold finger, this scatterometer operated at cryogenic temperatures, reaching vacuum level of 10−6 Torr and a temperature of about 7K. The implementation of the Gerchberg-Saxton error reduction and hybrid input-output phase-retrieval algorithms allowed for the reconstruction of the power spectral density function and the correct calculation of the surface autocorrelation function, providing a solution to the electromagnetic wave scattering inverse problem. A real-time visualization of autocorrelation function was achieved for femtosecond spectroscopy of phase-change materials. The development of parallel computational algorithms has been carried out by graphics processing unit (GPU) computing using Compute Unit Device Architecture (CUDATM) with an "NVIDIA Tesla K80" GPU, and the Compute Unified Fast Fourier Transform (CUFFT) parallel programming library. The parallel implementation of phase-retrieval algorithms provides ~30x speed-up and efficiency.