Optical sidebands have been generated with relative frequency tens to hundreds of GHz by using optical sidebands that are generated in a cascade process in high-quality optical resonators with Kerr nonlinearity, such as whispering gallery mode (WGM) resonators. For this purpose, the WGM resonator needs to be optically pumped at two frequencies matching its resonances. These two optical components can be one or several free spectral ranges (FSRs), equal to approximately 12 GHz, in this example, apart from each other, and can be easily derived from a monochromatic pump with an ordinary EOM (electro-optic modulation) operating at half the FSR
frequency. With sufficient nonlinearity, an optical cascade process will convert the two pump frequencies into a comb-like structure extending many FSRs around the carrier frequency. This has a demonstratively efficient frequency conversion of this type with only a few milliwatt optical pump power.
The concept of using Kerr nonlinearity in a resonator for non-degenerate wave mixing has been discussed before, but it was a common belief that this was a weak process requiring very high peak powers to be observable. It was not thought possible for this approach to compete with electro-optical modulators in CW applications, especially those at lower optical powers. By using the high-Q WGM resonators, the effective Kerr nonlinearity can be made so high that, using even weak seeding bands available from a conventional EOM, one can effectively multiply the optical sidebands, extending them into an otherwise inaccessible frequency range.
This work was done by Dmitry V. Strekalov and Nan Yu of Caltech for NASA’s Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Physical Sciences category. NPO-47322
This Brief includes a Technical Support Package (TSP).
Optical Sidebands Multiplier
(reference NPO-47322) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA’s Jet Propulsion Laboratory (JPL) concerning the Optical Sidebands Multiplier, referenced as NPO-47322 in NASA Tech Briefs. It outlines the technological advancements and research related to optical sidebands and their applications in aerospace and other fields.
Key components discussed include the use of lasers, specifically a Koheras laser operating at 1560 nm, alongside various optical and electronic instruments such as photodiodes, optical spectrum analyzers, oscilloscopes, and RF sources. The document emphasizes the importance of electro-optic modulators (EOMs) in generating sidebands, which are crucial for the operation of the optical sidebands multiplier.
The theoretical framework is grounded in the three-mode Kerr Hamiltonian, which describes phenomena such as self-phase modulation, cross-phase modulation, and four-wave mixing (hyperparametric conversion). These processes are essential for understanding Kerr interactions in whispering gallery mode (WGM) resonators, where two-mode (sideband) squeezing is anticipated. The document notes that measurements sensitive to photon-number correlations will exhibit sub-Poissonian statistics, indicating the presence of quantum correlations among photons.
The document also serves as a resource for those interested in the broader implications of these technologies, suggesting that the developments have potential applications beyond aerospace, including in telecommunications and quantum computing. It encourages collaboration and further inquiry into the innovative technologies developed under NASA's Commercial Technology Program.
For additional information, the document provides contact details for the Innovative Technology Assets Management at JPL, inviting inquiries related to research and technology in this area. It also includes a disclaimer regarding the proprietary nature of the information and the need to comply with U.S. export regulations.
Overall, the Technical Support Package highlights the intersection of advanced photonics and aerospace technology, showcasing NASA's commitment to fostering innovation and making significant technological advancements accessible for wider applications.
