  A periodically poled lithium niobate (PPLN) waveguide-based single-pixel
up-conversion infrared spectrometer was demonstrated. Sum-frequency generation
between a 1.5 micrometer band scanning pump laser and a 1.3 micrometer band
signal generated visible radiation which was detected by a silicon
single-photon detector. The noise equivalent power of the upconversion
spectrometer was two-orders-of-magnitude lower than that of a commercial
optical spectrum analyzer.
