Fig. 1. Conceptual representation of the proposed technique. A coaxially propagating orthogonally polarized beam encoded with helical and non-helical beams travels through the QWP placed at 45° for space division multiplexing and polarization filters that capture the multiple phase-shifted interferograms in a single shot.

Fig. 2. Schematic of the experiment to measure the OAM spectrum of the FVB in a single shot. MO, microscopic objective; P, pinhole; L, lens; HWP, half-wave plate; BS, beam splitter; SLM, spatial light modulator; QWP, quarter-wave plate. In the inset, the arrangement of the polarization filters embedded into a polarized camera and respective orientation angles are shown.

Fig. 3. Measuring the OAM spectrum from the experimentally recorded interferogram. (a) denotes single-shot recording interferogram and (b)–(e) show multiple phase-shifted interferograms corresponding to phase shifts of 0,π/2,π, and 3π/2, respectively, extracted from the single-shot recording interferogram. (f) represents the measured phase profile of FVB and the corresponding OAM spectrum is shown in (g).

Fig. 4. (a)–(d) Simulation results of FVBs with TC l=3.50, 3.75, 3.90, and 4.80, respectively. (e)–(h) Corresponding experimental results.

Fig. 5. OAM spectra of FVBs with TC l=3.50, 3.75, 3.90, and 4.80.

Fig. 6. OAM spectra of the FVBs with higher-order fractional TC l=15.87 and 29.80, and corresponding experimentally measured phases are shown in the inset.

Fig. 7. (a) OAM spectra of three different FVBs with TCs l=4.458, 4.498, and 4.537 and (b) accuracy verification.