Generation of Bessel Beams at mm- and Sub mm-wavelengths by Binary Optical Elements

Abstract

In this paper, binary optical elements (BOE's) are designed for generating Bessel beams at mm-and sub mm-wavelengths. The design tool is to combine a genetic algorithm (GA) for global optimization with a two-dimension finite-difference time-domain (2-D FDTD) method for rigorous electromagnetic computation. The design process for converting a normally incident Gaussian beam into a Bessel beam is described in detail. Numerical results demonstrate that the designed BOE's can not only successfully produce arbitrary order Bessel beams, but also have higher diffraction efficiencies when compared with amplitude holograms.

Quasi-Optical Bessel Resonator

“…Examples can be found in [7,8,[12][13][14][15][16]. To our knowledge, no active schemes have been reported at these wavebands as yet.…”

“…Numerous approaches to generate pseudo Bessel beams have been suggested, which can be sorted roughly into two classes [3][4][5], i.e., passive and active schemes. The first class uses the spatial filter to transform an incident beam into an approximation to Bessel beam, such as narrow annular slit [2], computer-generated holograms (CGHs) [6][7][8], Fabry-Perot cavity [9], optical refracting systems [10], axicon [11][12][13][14] and diffractive phase elements (DPEs) [15][16][17]. The other class is formed by methods relying on a resonator frame to produce the Bessel-type modes.…”

Properties of Approximate Bessel Beams at Millimeter Wavelengths Generated by Fractal Conical Lens

“…However, reasonably good approximations can be made. Currently, numerous approaches for generating Bessel beams have been proposed, such as axicons [4], computer-generated holograms (CGH's) [7,8] and diffractive optical elements (DOE's) [9], among which the simplest and easiest realization scheme is using axicons. Accordingly, much interest has been provoked in design and analysis of axicons [10], and the number of axicon applications has also increased significantly in the last few years [11].…”

Generation of mm- and Sub mm-wave Bessel Beams Using DOE’s Designed by BOR-FDTD Method and MGA

“…However, axicons can create only zero-order Bessel beams and the diffractive efficiencies of computer-generated amplitude holograms are only around 45% [2]. In order to produce arbitrary order Bessel beams and improve the diffractive efficiencies, more recently, we have employed binary optical elements (BOE's) to generate Bessel beams [16]. The design tool presented in [16] is to combine a genetic algorithm (GA) with a two-dimension finitedifference time-domain (2-D FDTD) method.…”

“…In order to produce arbitrary order Bessel beams and improve the diffractive efficiencies, more recently, we have employed binary optical elements (BOE's) to generate Bessel beams [16]. The design tool presented in [16] is to combine a genetic algorithm (GA) with a two-dimension finitedifference time-domain (2-D FDTD) method. Now, we present a new way for producing Bessel beams at mm-and sub mm-bands, in which DOE's are used to transform incident Gaussian beams into Bessel beams.…”