Evolution of conically diffracted Gaussian beams in free space

Abstract

We present results of our observations on the free space evolution of conically diffracted beams from both single and cascade systems using various combinations of four biaxial crystals of the monoclinic double tungstate family [KGd(WO4)2]. Longitudinal shifts and radii of the Hamilton-Lloyd pair of rings were measured. In each case, the symmetric - forward and backward - evolution of the beam in free space from its focal image plane was monitored and quantified. Theoretical ring plane patterns based on a recently presented theoretical model are also compared to experimental patterns and found to be in good agreement.

Conical refraction: fundamentals and applications

“…Although being the case of a Gaussian input beam the most studied situation in CR for cylindrically symmetric beams [33,[61][62][63][64][65][66][67][68][69], other works have investigated CR for Laguerre-Gauss beams [70,71] and for top-hat beams [72].…”

“…The transformation of a light beam consecutively passing through a series of BCs with aligned optical axes, i.e., cascaded CR, has been theoretically and experimentally investigated for a cascade of two , three , and up to four BCs, with interesting applications in lasing , particle trapping , vortex generation , and free‐space optical communications . The diffractive theory of CR has been extended by Berry to the case of cylindrically symmetric beams propagating through a cascade of up to N BCs , providing an accurate description of the phenomenon in terms of Bessel functions.…”

Voigt wave investigation in the KGd(WO4)2:Nd biaxial laser crystal

“…Optical trapping of micro-spheres [22] is another interesting application of optical axis wave propagation. The conical refraction of Gaussian beams in the KGW crystal was nicely studied (experimentally and theoretically) by some authors [23][24][25][26][27], while conical refraction of Laguerre-Gauss beams has distinct features [28]. The unique spatial polarization distribution inside the Airy disk area obtained from the conical refraction trough a thin biaxial crystal has been utilized in enhanced resolution microscopy [29].…”

Lasing with conical diffraction feature in the KGd(WO4)2:Nd biaxial crystal

“…Nowadays a few applications have emerged: polarization demultiplexing and multiplexing [15] for freespace optical communication, optical trapping of micro-spheres [16], enhanced resolution microscopy by sub-wavelength localisation [17][18], two-photon polymerisation [19], and polarimetry [20][21]. The agreement between the theoretical description and experimental data has been extensively published recently in the far field [22][23] as well as imaging the near field [24][25][26][27][28][29].…”