Transformation of the order of Bessel beams in uniaxial crystals

The optical transformation of a zeroth-order Bessel beam to a second-order Bessel beam is studied theoretically and experimentally in the case when the beam propagates along the optical axis of a uniaxial crystal. It is shown that, if the crystal length or the cone angle of the incident beam are chosen properly, the energy of the input field can be almost completely converted into a second-order Bessel beam.