Engineering the axial intensity of Bessel beams

Bessel beams (BBs) appear immune to diffraction over finite propagation distances due to the conical nature of light propagation along the optical axis. This offers promising advantages in laser fabrication. However, BBs exhibit a significant intensity variation along the direction of propagation. We present a simple technique to engineer the axial intensity of the BB over centimeters-long propagation distances without expansion of the incoming laser beam. This method uses two diffractive optical elements (DOEs), one converts the input Gaussian intensity profile to an intermediate intensity distribution, which illuminates the second DOE, a binary axicon. BBs of desired axial intensity distribution over few centimeters length can be fabricated.