Optical vortex with multi-fractional orders

Abstract

Recently, optical vortices (OVs) have attracted substantial attention because they can provide an additional degree of freedom, i.e., orbital angular momentum (OAM). It is well known that the fractional OV (FOV) is interpreted as a weighted superposition of a series of integer OVs containing different OAM states. However, methods for controlling the sampling interval of the OAM state decomposition and determining the selected sampling OAM state are lacking. To address this issue, in this Letter, we propose a FOV by inserting multiple fractional phase jumps into whole phase jumps (2π), termed as a multi-fractional OV (MFOV). The MFOV is a generalized FOV possessing three adjustable parameters, including the number of azimuthal phase periods (APPs), N; the number of whole phase jumps in an APP, K; and the fractional phase jump, α. The results show that the intensity and OAM of the MFOV are shaped into different polygons based on the APP number. Through OAM state decomposition and OAM entropy techniques, we find that the MFOV is constructed by sparse sampling of the OAM states, with the sampling interval equal to N. Moreover, the probability of each sampling state is determined by the parameter α, and the state order of the maximal probability is controlled by the parameter K, as K * N. This work presents a clear physical interpretation of the FOV, which deepens our understanding of the FOV and facilitates potential applications, especially for multiplexing technology in optical communication based on OAM.

Unraveling the vector nature of generalized space-fractional Bessel beams

“…This work also serves as a call for experiments to generate the proposed solution of space-fractional Bessel beams by making use of a digital micromirror device (DMD) or a spatial light modulator as discussed in [24,27,[44][45][46]. The same beam can also be generated using strategies mentioned in [17][18][19][20] in order to have on-chip solutions that can be easily employed in a wide variety of applications in different fields of optical engineering like in laser cutting, optical tweezing and optical communications etc.…”

“…Moreover, like other fractional and integer Bessel beams, and structured light beams, the proposed SFBBs can also be generated easily using SLMs that have the ability to modulate the amplitude, phase or polarization of the light waves in space and time and are widely used now a days to generate arbitrary shaped beams such as anti-diffracting optical pin beams, fractional Bessel beams, vortex beams and optical tweezers etc. at the desired wavelengths with high efficiency [44][45][46].…”

Rigorous estimation of the LC director distribution and its influence on light propagation in LC-based optical devices

“…7 Of paramount importance is the dynamic control of the voltage applied to each pixel, a critical function that has garnered considerable attention across multiple fields. These include but are not limited to head-up displays, 8,9 holographic threedimensional (3D) displays, 10,11 laser processing, 12 3D printing, 13 optical communication, 14 optical computing, 15 holographic data storage, 16 and diffractive optical elements. 17 The properties of optical and dielectric anisotropy, joined with the non-linear behaviour of LC material to the applied electric field, have become LC the focus of many researchers for novel applications, 3 and further breakthroughs are expected due to the reduction of the pixel sizes, thus making it possible to address highfrequency patterns impossible to use a few years ago.…”