We report an Yb-doped fiber master-oscillator power-amplifier (MOPA) system with the capability of selectively generating doughnut-shaped radially and azimuthally polarized beams with user-defined temporal pulse shapes. The desired output polarization was generated with the aid of a nanograting spatially variant half-waveplate (S-waveplate). The latter was used to convert the linearly polarized fundamental (LP) mode output from the preamplification stages to a doughnut-shaped radially polarized beam prior to the power amplifier stage. A maximum output pulse energy of ∼860 μJ was achieved for ∼100 ns pulses at 25 kHz with user-defined pulse shape for both radial and azimuthal polarization states. The polarization purity and beam propagation factor (M) were measured to be >12 dB and 2.2, respectively.
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http://dx.doi.org/10.1364/OL.42.001740 | DOI Listing |
Taking into account phase-polarization interactions is crucial for the formation of spatially structured laser beams. The effects that arise in this context can lead to the modulation of individual field components and the transformation of the overall light field. In this study, we investigate the impact of phase and polarization distributions with radial dependencies in polar coordinates on the longitudinal component of laser beams passing through a transmissive spatial light modulator (SLM) based on twisted nematic liquid crystals.
View Article and Find Full Text PDFACS Photonics
December 2024
Graduate School and Faculty of Information Science and Electrical Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
Whispering-gallery mode (WGM) resonators, renowned for their high Q-factors and narrow line widths, are widely utilized in integrated photonics. Integrating diffraction gratings onto WGM cavities has gained significant attention because these gratings function as azimuthal refractive index modulators, enabling single-mode WGM emissions and supporting beams with orbital angular momentum (OAM). The introduction of curved grating structures facilitates guided mode resonances by coupling high-order diffracted waves with leaking modes from the waveguide.
View Article and Find Full Text PDFJ Colloid Interface Sci
March 2025
Department of Mechanical Engineering, Baylor University, One Bear Place #97356, Waco, 76798, TX, United States. Electronic address:
This study reveals how drops impacting thin liquid films leave behind radial microbubble trains - here defined as large-area microbubbles (LAMs) - over a region comparable to the maximal surface coverage of the spreading phase. Using a thin, minimally compliant viscous oil film, the trapped bubbles are immobilized and quantified via high-speed imaging techniques across varying drop velocities and surface inclinations. The setup enables the characterization of microbubble entrainment (e.
View Article and Find Full Text PDFVortex retarders are optical retarders with a uniform retardance, but with a fast axis that varies azimuthally over the area of the optic. This affects the radial and azimuthal polarization components of the incoming beam. The vortex retarders discussed here generate TEM and TEM Laguerre-Gaussian beams.
View Article and Find Full Text PDFWe experimentally demonstrate a 10-Gbit/s free-space communication link using a single Laguerre-Gaussian (LG) beam with tunable radial and azimuthal modal indices generated by a photonic integrated circuit comprising two concentric uniform circular antenna arrays (UCAs). To tune the azimuthal modal indices ℓ of the generated beam, the azimuthal phase gradient inside each UCA is tuned. To tune the radial mode p of the generated beam, the amplitude ratio and phase difference between the two concentric UCA are tuned.
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