Creating an Array of Parallel Vortical Optical Needles

Abstract

We propose a method for creating parallel Bessel-like vortical optical needles with an arbitrary axial intensity distribution via the superposition of different cone-angle Bessel vortices. We analyzed the interplay between the separation of individual optical vortical needles and their respective lengths and introduce a super-Gaussian function as their axial profile. We also analyzed the physical limitations to observe well-separated optical needles, as they are influenced by the mutual interference of the individual beams. To verify our theoretical and numerical results, we generated controllable spatial arrays of individual Bessel beams with various numbers and spatial separations by altering the spectrum of the incoming laser beam via the spatial light modulator. We demonstrate experimentally how to implement such beams using a diffractive mask. The presented method facilitates the creation of diverse spatial intensity distributions in three dimensions, potentially finding applications in specific microfabrication tasks or other contexts. These beams may have benefits in laser material processing applications such as nanochannel machining, glass via production, modification of glass refractive indices, and glass dicing.

Nanosecond Laser Fabrication of Dammann Grating-like Structure on Glass for Bessel-Beam Array Generation

“…Prior to this longitudinal distance, overlapping of adjacent Bessel rings occurs, as evident from Figure 5e. Such features were earlier observed for both zero-order and high-order Bessel beams [25,26]; the authors observed that the complete radial separation between adjacent Bessel beams depends on the longitudinal distance of Bessel beams. Contrastingly, in case of the 800 µm period grating, it was observed that the three wellseparated Bessel beams appear only beyond a longitudinal distance of 400 µm.…”

Plasmonic Focusing of a High-Order Cylindrical Vector Beam for On-Chip Detection

“…High-order vectorial polarization states have also been widely investigated [4,5]. In contrast to the conventional linearly polarized beam, CVBs possess strong longitudinal/transverse field components in focusing [6][7][8][9][10], giving rise to many intriguing phenomena such as spin-orbit interaction [11], optical needles [12], and the topological structure of light [13][14][15][16][17], as well as a variety of applications including optical trapping [18][19][20][21], optical lithography [22,23], and optical micro-fabrication [24,25].…”