A mixed multi-order vortex beam generator, based on a Reuleaux triangle core fiber chiral grating (RCFG), is proposed. The triangular perturbation and off-axis effects induced by core shape, result in the simultaneous coupling of the core mode with the 1st- and 3rd-order vortex modes. To the best of our knowledge, this is the first time that a mixed vortex beam was generated in a single chiral fiber. The phase matching conditions required for the co-coupling of multi-order vortex beams are analyzed based on the coupled mode theory. Additionally, a cladding shrinkage method is proposed to flexibly adjust the co-coupling wavelength. We found that the key to co-coupling lies in balancing the different order perturbations of the Reuleaux triangle core fiber (RTF). The proposed method offers a new approach for the design of mixed multi-order vortex beam generators, with potential applications in fields such as fiber OAM communications, optical tweezers, and super-resolution imaging.
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http://dx.doi.org/10.1364/OE.507169 | DOI Listing |
The orbital angular momentum (OAM) of beams provides an additional degree of freedom and has been applied in various scientific and technological fields. Accurate and quantitative measurement of intensity distributions across different OAM modes, referred to as the OAM spectrum of a beam, is crucial. Here, we propose a straightforward and efficient experimental setup for measuring the OAM spectrum of a randomly fluctuating beam.
View Article and Find Full Text PDFThe spin-orbit ( - ) interaction in a focused-reflected beam of light results in spatially nonuniform polarization in the beam cross section due to the superposition of orthogonal field components and polarization-dependent interface reflection coefficients. Polarization filtering the output beam leads to an interchangeable transformation of =∓2 charge vortex into two (∓) unit charge vortices, for = ±1 circular polarization of the input Gaussian beam. This transformation follows a trajectory, named optical vortex trajectory, that depends on the input beam's and hence the and reflecting surface characteristics.
View Article and Find Full Text PDFWe demonstrate the generation of stable femtosecond vortices from a self-started Kerr-lens mode-locked Yb:YAG thin-disk oscillator. By using a defective mirror inscribed with a fine line, 218-fs Hermite-Gaussian (HG) pulses are delivered directly from the thin-disk oscillator with an average power of 12 W at the repetition rate of 105 MHz and subsequently converted to Laguerre-Gaussian (LG) vortices by a cylindrical-lens mode-converter. The average output power of the Hermite-Gaussian pulses is further improved to 19 W by applying a rectangular aperture.
View Article and Find Full Text PDFNanophotonics
February 2024
Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices, Air Force Engineering University, Xi'an, Shaanxi 710051, China.
Nanophotonics
September 2024
Air and Missile Defense College, Air Force Engineering University, Xi'an 710051, China.
Achieving independent multitasked wavefront control by using an ultrathin plate is a challenge to increase information capacity in integration optics and radar applications. Transmission-reflection-integrated metasurface provides an efficient recipe primarily for multifunctional meta-device, however it is challenging to synergize both linear polarization (LP) and circular polarization (CP) using a single meta-plate. Here, a multichannel full-space coding metasurface composed of interleaved shared-aperture meta-atom is proposed to achieve large information capacity by capsulating judiciously engineered high efficiency triple sub-elements (modes) in four-layer scheme.
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