Recent Progress in Nonlinear Frequency Conversion of Optical Vortex Lasers

Abstract

Optical vortices are optical fields that possess a helical phase and orbital angular momentum, which have found the application in micromanipulation, optical communication, orbital angular momentum entanglement, super-resolution imaging, metrology, etc. The urgent need for the wide spreading applications of vortex lasers is to increase the wavelength versatility. In this study, the nonlinear frequency conversion of vortex lasers with a focus on sum frequency generation stimulated Raman scattering, and optical parametric oscillators were meticulously reviewed. The characteristics of the topological charge transfer and output beam profiles of different frequency conversion were discussed. As the precise tuning of optical fields in both temporal and spatial domains shall be the trend of future studies, it is our hope that this review shall serve as a reference for future research. Combining these techniques with the streaming methods to produce optical vortices, i.e., annular pump, off-axis pump, reflection mirror with defect spots, spherical aberration, and birefringence, it is advisable to expand the wavelength and fill the wavelength gap in the ultraviolet, visible, and infrared bands.

Tunable Near and Mid-Infrared (1.3–5 µm) Picosecond Pulsed Optical Vortex Parametric Oscillator

“…As such, it is crucial that new techniques are developed which can facilitate such diversity and control, and thus expand the range of applications for these types of beams. Nonlinear frequency conversion techniques including second-harmonic generation [15], sum-frequency generation [16,17], optical parametric oscillation (OPO) [18][19][20][21][22], optical parameter amplification [23], and stimulated Raman scattering [24] are perhaps the most commonly applied laser wavelength conversion techniques. In particular, OPOs are commonly used for the generation of nearto mid-infrared, continuously wavelength-tunable laser emissions with high output power, and work across all temporal modalities (continuous wave to ultrashort pulse).…”

Second-Harmonic Generation of the Vortex Beams with Integer and Fractional Topological Charges

“…In 2017, J. P. Leonardo et al investigated the nonlinear mixing of OAM in type-II SHG with arbitrary TCs imprinted on two orthogonally polarized beams [31]. In addition to the investigation of the SHG of LG vortex beams, researchers also focused on other vortex beams, such as BG beams [32][33][34][35][36][37], composite vortex beams [38,39], fractional vortex beams [40][41][42][43], perfect vortex beams [44], etc. As far as we know, few researchers have studied the variation of the waist radius in single-pass SHG and the effect of the vortex order (or the TC) on the SHG efficiency in experiments.…”

An Axicon-Based Annular Pump Acousto-Optic Q-Switched Nd:GdVO4 Self-Raman Vortex Laser

“…Carrying spiral wavefront and central phase singularity, optical vortices are known as a kind of beam with doughnut intensity distribution [1]. Given their unique structure, many applications have been found in fields such as optical tweezing, particle manipulation, optical communication, topological quantum simulation, ultra-resolution imaging, chiral processing and astronomy [2][3][4][5][6][7][8][9].…”