Wavelength Conversion Module for Visible, Near-IR, and Mid-IR Light Generation

product image NEL produces periodically poled lithium niobate(PPLN) waveguide modules for visible, near-IR, and mid-IR light generation. The module consists of a PPLN waveguide, a thermoelectric cooler, and a thermistor. A custom design of the poling period is available. Please specify your pump and SHG/SFG/DFG wavelenghts down to 2 decimal places when ordering modules.


The quasi-phase matched PPLN waveguide modules provide a variety of wavelength conversion capability without using cavity structures.

quasi-phase matching

Second harmonic generation(SHG), sum frequency generation(SFG), and diffrence frequency generation(DFG) are second-order nonlinear optical processes. The second order dipole polarization is induced by electric fields of input lights. In the phrase of quantum optics, a new photon is generated from input two photons. The interactions are expressed as follows;

SHG (for example 532 nm)

SHG image

SFG (for example 578 nm)

SFG image

DFG (for example 3 μm)

DFG image

Quasi-phase matching is achieved by inverting the porlarization every half of the coherence length with respect to the light propagation direction.
For more information, please refer following references.

  1. A. Yariv and P. Yeh, Photonics: Optical Electronics in Modern Communications (Oxford University Press, 2007)
  2. M. Asobe et al., IEICE Trans. Electron. E88-C, 335 (2005)

ridge waveguide

The wavelength conversion is limited by the beam divergence in bulk PPLN crystals. However, in PPLN waveguide, the wavelength conversion is enhanced by the beam confiment effect throughout the waveguide length . The conversion efficiency of the PPLN waveguide is two order of magnitude larger than that of bulk PPLN crystal.

waveguide image

Typical conversion efficiency of PPLN waveguide is larger than 100%/W at visible region. Conversion efficiency η is defined as

          Pk = η Pl Pm

where Pk is output power (k = 2ω at SHG, ωp at SFG, ωi at DFG) while Pl and Pm are input power (l = m = ω at SHG, l = ωs and m = ωi at SFG, l = ωp and m = ωs at DFG).


Polarization should be parallel to the connector's key direction.



No. Description No. Description
2 Termistor 6 Termistor
4 Cooler (+) 8 Cooler (-)


(1)SFG (578 nm)

Item Spec
Model WS-0578-000-A-B-C
Required pump wavelengths 1030 nm   1319 nm
SFG wavelength 578 nm
Efficiency > 100 %/W
When pump power is below 100 mW
Operation temperature(Top) Typ.: >30 degree C
Temperature fine tuning is required for satisfying the phase match condition
Thermister B=3450
TEC Current 2 A max
Module size 54 mm x 30 mm x 11.2 mm
Window IR-cut filter or Visible-AR window
Input fiber※ 980 nm PANDA fiber with FC / APC connector

※WDM fiber coupler is not included.

Photonics top

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