High Power Fiber Lasers Utilizing Intermodal Nonlinearities
Abstract
The goal of this BRI program is the investigation of novel nonlinear effects and phenomena by (1) exploiting the higher dimensional design space afforded by higher order modes (HOM) in fibers, as well as the subset of such modes that carry orbital angular momentum (OAM), and (2) enable nonlinear fiber optics at high pulse energies, currently critically limited by the low power handling constraints of photonic crystal fibers. Applications range from underwater communications and sensing to quantum encryption and imaging. Unlike in crystals, parametric processes in optical fibers exploit the third order (3) nonlinearity, which need phase matching to be efficient. In a single-mode system, phase matching is obtained by control of the chromatic dispersion of an optical fiber; specifically it requires that the zero-dispersion of the medium or waveguide be spectrally proximal to the pump wavelength. To achieve this at user-defined pump wavelengths, especially in the visible or near-IR spectral range, a fundamental requirement is for the mode area to be decreased in Silica-based fibers (other fiber materials have, to date, not been shown to be stable enough to be viable as high-power hosts). This can be readily achieved with photonic crystal waveguides and fibers, but this methodology yields color-tunability at the expense of pulse energy, since mode area has to be continually decreased as the pump wavelength decreases. In this program, we leveraged recent advances in optical fibers, which showed that sufficiently high order HOMs are stable, even over lengths exceeding km. As such, a multimode fiber (MMF) platform provides for a countably infinite number of select (but not all) spatial modes that do not uncontrollably mix, yielding mode distortions and speckle patterns that have been considered unavoidable in MMFs.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 30, 2024
- Accession Number
- AD1230665
Entities
People
- Siddharth Ramachandran