Calculate the single-atom upper-bound cutoff EUV photon energy one can expect to generate with the classical model by calculating the Ponderomotive energy and using the gas-specific ionization energy.
However knowing the single atom cut-off energy is insufficient, phase matching is also a critical criteria that needs fulfilled in HHG operation and KMLabs has decades of expertise in this area.
3.17Up+Ip=3.17x9.337381.2 x π ωo2Eτλ2 + Ip=
[Cutoff Photon Energy] = eV
M2, a measure of pump laser beam quality, usually in the range of 1-2, is assumed to be 1.2 here, which is typical. Up is called Ponderomotive potential.
Pulse energy E (mJ)
Beam waist ωo (μm) in radius
Pulse duration τ (fs)
Center wavelength λ (nm)
Ionization potential based on gas type
Cutoff Photon Energy
Typical range of EUV photon energy
Output EUV photon energy range in practice may differ depending on final setup from the given general reference info below.
Common pump laser center wavelength
Common gas type
Krypton/Xenon usually can reach lowest attainable harmonic order with a given pump laser with lower minimum requirements on pump pulse energy. Neon is good for intermediate photon energy ranges with narrow harmonic linewidths.
HHG photon energy range
KMLabs has experience generating UV photons in the range of 6-18 eV (68-206 nm) or Soft X-ray photons up to 1,600 eV (0.77 nm). Consult us if your desired photon energy is outside the estimated photon energy.
24 eV53 nm
55 eV23 nm
50 eV24 nm
75 eV16 nm
83 eV15 nm
120 eV10 nm
18 eV69 nm
30 eV41 nm
32 eV38 nm
62 eV20 nm
Minimum needed pump pulse energy
Optimal parameters to be used in practice may differ based on customer specific requirements from the given general reference information here.
HHG wavelength of interest, within 10 - 70 nm
Invalid input, beyond KMLabs standard EUV HHG, contact us for SXR HHG instead.Invalid input, input wavelength too long for HHG, contact us for VUV instead.Invalid input.
2 mJ using He Gas
1 mJ using Ne Gas
0.1 mJ using Ar Gas
1 mJ using Ar Gas
2 mJ using Ne Gas
5 mJ using Ne or He Gas
At-source photon flux vs. repetition rate
The plots are to illustrate a general trend and not exactly to scale.
Typical operation parameters in HHG
Over-driven scenarios see an increased flux while other beam quality metrics worsen, e.g. bandwidth, pointing stability, etc.
HHG beam spot size
Acceptable pump beam input spot size :
4 - 13mm in diameter
Nominal spot size at HHG source output :
50 𝛍m in diameter
Nominal spot size at sample
KMLabs has achieved customized spot sizes from ~5-10𝛍m to ~1mm or more at sample. Consult us for more information.
( 1:1 or assuming typical demag ratio range , ~6 ft beamline from source ) :
30 - 200 𝛍m in diameter
HHG harmonic bandwidth
Normal bandwidth of a single harmonic :
Different requirements on the bandwidth or bandwidth related parameters may be achieved via customization, consult us for more information.
Measured at 1.0 - 1.4eV max. ( He , 13nm , 2mJ), Measured at 0.3 -0.7eV max. ( Ar , 30nm , 0.5mJ ), Measured at 0.05 - 0.2eV max. ( Ne , 60nm , Yb, 1mJ ), resolution - limited by KMLabs standard imaging spectrometer configuration.