Laser mode discrimination with intra-cavity spiral phase elements

Abstract

A novel method for discriminating and selecting a specific high order mode is presented. It is based on introducing spiral phase elements into a laser resonator, so as to improve the output beam quality over that when the laser operates with multi-modes, and yet maintain a relatively high output power. The theoretical analysis, along with experimental results with CO and Nd:YAG lasers are presented. The results reveal that a 50% increase of laser output power over that operating with 2 TEM mode is possible. q

Laguerre-Gaussian modes selection in diode-pumped solid-state lasers

“…5) Selection of LG pm transverse modes (p; m 4) in a flash-lamp-pumped Nd:YAG laser was achieved by inserting intra-cavity phase elements. 16,17,42,43) Special resonator configurations, such as unstable resonators, self-imaging, Fourier and polarization selective resonators were used to promote the oscillation of some specific modes and suppress others. 19) Intra-cavity elements and special resonator configurations are in use for mode selection in DPSSLs as well.…”

“…Several transverse HG and LG modes were selected in He-Ne gas lasers, 4,5) and then higher order modes were investigated in other types of gas, solid-state and semiconductor lasers. [7][8][9][10][11][12][13][14][15][16][17][18] Generally, intra-cavity elements for mode selection are introduced in the laser resonator in order to produce low losses for a specific desired mode and high losses for other modes. Mode selection techniques based on the usage of intra-cavity apertures, phase plates, gradient mirrors and on different resonator configurations were reviewed by Oron et al 19) The number of reports on mode selection in solid-state lasers has dramatically increased during the last two decades with the advent of diode-laser pumped solid-state lasers (DPSSLs).…”

“…28) Numerous applications of scalar LG modes, covering several fields in physics, have been found: oam transfer to small particles, 29,30) cold atoms and particles trapping, [31][32][33][34][35] quantum information, 36) high resolution microscopy, 37,38) material processing, 39) etc. A large number of publications exist on the methods of formation of scalar LG modes both inside the cavity (active methods) 16,17,[40][41][42][43] and outside (passive methods), [44][45][46][47] where mode conversion to the required mode was achieved using holograms, spatial light modulators and diffractive optical elements.…”

Generation of a Purely Single Transverse Mode Vortex Beam from a He-Ne Laser Cavity with a Spot-Defect Mirror

“…By contrast, direct generation from a laser cavity is expected to improve the beam quality due to an inherent feedback effect in the cavity. Although many attempts have been reported, for example, a ring-shaped beam pumping [12], the thermal lensing effect in a diode-side-pumped bounce laser cavity [13], the insertion of a spiral phase plate [14], and the use of a circular absorber [15][16][17], most of them have merely reported the generation of the LG beam without a detailed evaluation of the beam purity and quality. Recently, we have demonstrated the generation of LG beams from a Nd : yttrium aluminum garnet (YAG) laser cavity using a spot defect mirror [18].…”

Generation of very-high order Laguerre-Gaussian modes in Yb:YAG ceramic laser

“…Methods for LG p,l mode formation directly in a solid-state laser cavity using phase elements were developed [5,13]. "Hollow" LG 0,l (l > 0) beams of high azimuthal order were produced in Nd:YAG and Nd:YVO 4 lasers by shaping pump beam intensity profiles [8,9,11,14].…”