Abstract
An end-pumped Nd:YVO4 laser under selective pumping is used to excite lasing modes with transverse patterns performed to exhibit the characteristics of multiple spots arranged on elliptical features near degenerate cavities. The spatial distribution of elliptical lasing modes is clearly revealed to be localized on the nonplanar ray orbits, so-called nonplanar elliptical modes, which possess large fractional orbital angular momentum. Moreover, temporal dynamics for the output emission of nonplanar elliptical modes are verified to obtain self-mode-locked operation. We further numerically manifest not only the influence of radial-asymmetry distributions on the vortex structures of nonplanar elliptical modes, but also the vector field of transverse lasing modes altered with twisting phase structures in the propagation direction.
Highlights
Techniques of self-mode locking with a decrease of cavity length for developing highrepetition-rate optical pulses is an interesting phenomenon without using active elements or saturable absorbers [1]
The simultaneously self-mode locking can be seen to be a time-dependent wave packet with dynamical behaviors corresponding to the planar periodic ray trajectories inside the cavity, known as planar geometric modes [11,12]
It is believed that the investigation of nonplanar elliptical modes with the self-mode-locked operation and the spiral features carrying huge fractional orbital angular momentum (OAM) is an important step in the structure light to be exploited in numerous applications
Summary
Techniques of self-mode locking with a decrease of cavity length for developing highrepetition-rate optical pulses is an interesting phenomenon without using active elements or saturable absorbers [1]. The generalized multipass beams in a three-dimensional (3D) laser resonator near the degenerate cavities can be localized on the nonplanar ray orbits, described as nonplanar geometric modes. The transverse pattern of nonplanar geometric modes is performed to demonstrate the property of multiple spots arranged on the topological trajectories. The topological trajectories are altered with the relative phase φ between the degenerate eigenmodes from the line feature at φ = 0 (i.e., planar geometric modes) through the elliptical shape in the range of 0 < φ < π / 2 and to the circular form at φ = π / 2. It is believed that the investigation of nonplanar elliptical modes with the self-mode-locked operation and the spiral features carrying huge fractional OAM is an important step in the structure light to be exploited in numerous applications. In this work we exploit a diode-end-pumped Nd:YVO4 laser with selective pumping to produce the nonplanar elliptical modes near the degenerate cavities. It is further observed that the vector field of transverse lasing modes is displayed swirling features along the elliptical structure at the beam waist, and altered with the twisting phase angle field in the propagation direction
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