Integrated photonic emitter with a wide switching range of orbital angular momentum modes

Abstract

Due to the nature of infinite dimensionality, the orbital angular momentum (OAM) has been considered as a new degree of freedom of light and widely expanded the scopes of substantial optical applications such as optical telecommunication, quantum information, particle manipulation and imaging. In recent years, the integrated photonic OAM emitters have been actively investigated due to both compactness and tunability. Essentially, the number of available OAM modes by dynamic switching should be large enough so that the dimensionality of OAM could be explored as much as possible. In this work, an integrated photonic emitter with a wide switching range of OAM modes is theoretically developed, numerically simulated, and experimentally verified. The independence of the micro-ring cavity and the scattering unit provides the flexibility to design the device and optimize the performance. Specifically, the dynamic switching of nine OAM modes (l = −4 ~ 4) with azimuthal polarization has been demonstrated by electrically controlled thermo-optic effect.

An InP-based vortex beam emitter with monolithically integrated laser

“…Compared with OAM emitters based on a circular grating coupler 20 or a microring resonator with download units 21 , 22 , optical vortex emitters based on a microring with angular gratings are highly compact. The radius of the microring can only be a few micrometers long, making the device particularly attractive for dense photonic integration 19 .…”

“…Compared with the bulky optical components typically used for OAM beam generation, such as spiral phase plates 16 , cylindrical lens-based mode converters 17 , or forked holograms implemented with spatial light modulators (SLMs) 18 , chip-based optical vortex emitters offer a much more compact and robust solution. To date, most chip-scale OAM beam emitters are based on silicon or silicon-on-insulator (SOI) wafers 19 – 22 , which are attractive because of the strong optical confinement and mature fabrication technology. However, the indirect bandgap of silicon means that an external laser must be employed to pump the OAM emitter, thus making monolithically integrated OAM emitters very challenging.…”

Characterization of an Eight-Element Circular Patch Array for Helical Beam Modes

“…In the following we briefly outline three methods in which HB characteristics may be quantified in some sense. The first is commonly used in optics and involves the concept of topological charge (TC) [15]. It is useful for determining the helical mode content of a beam and the frequency dependence of each mode.…”

Near-Infrared OAM Communication Using 3D-Printed Microscale Spiral Phase Plates

“…This approach includes the use of photonic structures in the form of a metamaterial, ring-shaped waveguide using the standard distributed Bragg reflector (DBR), and microring cavity using the azimuthal DBR or grating with whispering gallery modes. The monolithically integrated distributed feedback (DFB) semiconductor laser with a microring cavity [10], microringbased tunable OAM emitters [11], and novel structure OAM (de)multiplexers [12] have been experimentally demonstrated. The direct scheme is preferred for small footprint and device applications with a fixed OAM mode output, which enables the near-lossless generation of high-purity beams.…”