An all-optical microwave oscillator is proposed and experimentally demonstrated. Based on a pure photonic feedback loop, this system can generate a photonic microwave signal without optical-electrical-optical conversion or any electrical microwave devices. A semiconductor optical amplifier implements the functions of microwave envelope detection and feedback modulation. Meanwhile, Brillouin-selective sideband amplification is employed to lock oscillation frequency. In experiment, a good quality microwave signal with a frequency of 10.8 GHz is obtained. The tunability is also demonstrated by adjusting the Brillouin pump wavelength.
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http://dx.doi.org/10.1364/OL.43.001774 | DOI Listing |
Nanophotonics
May 2024
Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK.
Science
November 2024
Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA.
The tunability and spatial precision of paramagnetic molecules makes them attractive for quantum sensing. However, usual microwave-based detection methods have poor temporal and spatial resolution, and optical methods compatible with room-temperature solutions have remained elusive. In this study, we utilized pump-probe polarization spectroscopy to initialize and track electron spin coherence in a molecule.
View Article and Find Full Text PDFA new microwave photonic structure for measuring the frequency of an RF signal, to the best of our knowledge, is presented. The frequency of an unknown RF signal can be determined by simply measuring the system output optical powers. The proposed frequency measurement system can be designed so that the ratio of the two system output optical powers as a function of the RF signal frequency or the amplitude comparison function (ACF) has a steep linear slope over a wide frequency range.
View Article and Find Full Text PDFSmall
October 2024
Research Center for Green Advanced Materials, Sun Moon University, Chungnam, 31460, Republic of Korea.
The crystal structure and phase stability of a host lattice plays an important role in efficient upconversion phenomena. In stable hosts, lanthanides doping should not generally change the crystal structure of the host itself. But when phase of a system drastically changes after lanthanide doping resulting in multiple phases, accurate identification of upconverting phase remains a challenge.
View Article and Find Full Text PDFACS Appl Mater Interfaces
May 2024
School of Physics & Information Technology, Shaanxi Normal University, Xi'an 710119, China.
As a member of transition metal dichalcogenides (TMDs), NbTe has a work function of 5.32 eV and a band gap of 0 eV at the Fermi level, which enables it to possess broadband absorption characteristics and has huge potential in optoelectronic devices. In this work, a combination of liquid phase exfoliation (LPE) and optical deposition methods (ODMs) were used to fabricate a NbTe saturable absorber (SA).
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