Wavelength converter

measuringsignal

The core of the NLIR technology is the wavelength conversion module that upconverts mid-infrared wavelengths to near-visible, enabling the use of Si and GaAs detectors. Read more about how the conversion works in “Technology”. Accepted wavelengths are in the bandwidth 1.9 – 5.3 µm, and they are upconverted to the bandwidth 682 nm – 886 nm by a 1064 nm high-power laser inside a LiNbO3 crystal. Only the vertical polarization component is upconverted, which may reduce the amount of signal converted but correspondingly it also reduces the converted noise to half. After conversion, efficient spectral filtering below 695 nm and above 886 nm cuts away residual noise. The size of the bandwidth in an upconversion module has a significant impact on the efficiency of photon conversion. For the smallest bandwidths of around 50 nm, the conversion efficiency can reach up to 0.1, enabling extremely sensitive measurements. Meanwhile, wider simultaneous conversion such as 3.3 µm to 5.3 µm results in a conversion efficiency of approximately 0.005, and even wider conversion from 1.9 µm to 5.3 µm has a conversion efficiency of 0.0005. The ideal combination of bandwidth and conversion efficiency varies depending on many factors, but even the lower conversion efficiencies offer new possibilities for measuring, particularly in spectroscopic applications. Higher conversion efficiencies, coupled with the right visible-light detector, can provide some of the fastest and most sensitive infrared measurement methods available. The translation to near-visible wavelengths gives further advantages than lower noise-equivalent power.