Measured K-band luminosities of identified rotation-powered pulsars (filled circles) and available upper limits plotted as a function of the rotational energy loss rate Ė (updated from Mignani et al. 2007b). Different pulsars are labelled accordingly (see legenda). The plotted errors on the K-band luminosity account for the uncertainties on the flux measurements, the extinction correction, and the nominal pulsar distance. For PSR B0540−69, the error is comparable with the size of the symbol. The star indicates the candidate nIR counterpart to the X-ray pulsar IGR J18490−0000 (Ratti et al. 2010; Curran et al. 2011).