BESSEL-LIKE BEAM GENERATOR (Code BE-01)

SPECIFICATIONS

Substrate Material:   Glass
Substrate Diameter:  25.4 mm
Active Area:  5x5 mm2
Active Area Material:  SZ2080
Period between Structures:  ~60 µm
Diameter of Structures:  ~20 µm
Height of Structures:   ~8 µm
Initial Spot Size:  ~5 µm
Focal Length:  ~220 µm
Depth of Focus:  ~70 µm
Damage Threshold 1-on-1:  1.04 ±0.62 J/cm2
Damage Threshold 1000-on-1:
 0.67 ±0.40 J/cm2
Transmission >95%:  550-2000 nm
Recommended Wavelength:  633 nm
  
 Price: 100 Eur/pc

Different Bessel-like beam specifications are available by request.

Attention: First item may be sent free of charge for research purposes*. 
* delivery charges should be covered by the customer. The customer must share research data with Plazmonika team.

DESCRIPTION

Optical element generates Bessel-like beams array. The generated beams exhibit all the fundamental features of a Bessel-like beam:                   1) the transverse intensity profile (black line) matches the Bessel beam transverse intensity distribution (red line):

2) the axial divergence of the central beam (black line) is significantly lower than that of the Gaussian beam with the same initial waist size (red line):

SEM MICROGRAPHS OF STRUCTURES

BEAM PROPAGATION

TRANSMISSION SPECTRA OF SZ2080

Transmission spectra of hybrid organic-inorganic Zr-containing negative photoresist SZ2080 enriched with the photoinitiator 4,4‘-bis(dimethylamino)-benzophenone (concentration by weight equal to 1%). The thickness of the photopolymer layer is ~2 µm.

APPLICATIONS

Optical elements were tested in imaging applications. "CP" letters were taken using optical element consisting of polymeric structures generating Bessel-like beams.

Optical elements were tested in laser microfabrication. The example of the fabricated ring-shape structures containing gold nanoparticles. Such structures can be used in Raman spectroscopy.

PRINCIPLES OF BESSEL-Like BEAM GENERATION 

Bessel-like beams were generated using polymeric structures having significant spherical aberrations. In this case, extended Bessel-zones are obtained compared to the case of cone-shaped axicons. The comparison of Bessel beam generation using the spherically-shaped structure and axicon is given below.


In spherically-shaped structures, the transversal spatial frequency in the Bessel zone is slightly varying with the axial position z. The variation of the spatial frequency of the Bessel-like fringe pattern means that the conical beam angle β is a function of the axial position z (β(z)), contrary to an “ideal” axicon (conical-shaped) where β is an invariant along the axial position z.

GAUSSIAN BEAM VS BESSEL BEAM

Properties  Gaussian beamBessel beam 
 Propagation invariance - + 
 Self-reconstruction -+

Bessel beams due to their unusual properties (propagation invariance and self-reconstruction) are widely used in many fields:

  • Optical manipulation
  • Fabrication of polymer microfibers
  • Optical lithography
  • Microscopy
  • Cell transfection
  • Virtual tips for near-field optics
  • Optical pumping
  • Laser drilling
  • Imaging
  • Atomic transport and trapping
  • etc.