Semiconductor nanowires have a number of advantages over thin films and bulk analogues, which allow them to be used to develop efficient detectors and light sources. In this work, photoluminescence spectra of pure InAs and core-shell InAs/CaF2 and InAs/InP nanowires on silicon were studied in the near infrared spectral range at various levels of optical pumping and at different temperatures using a vacuum Fourier spectrometer operating in a step-scan mode. The observed peaks in the photoluminescence spectra correspond to interband transitions in InAs of sphalerite and wurtzite phases. The photoluminescence spectra of CaF2-coated InAs nanowires demonstrated that surface passivation with CaF2 does not change the spectral features. It was shown that the absolute value of photoluminescence intensity of InAs-core/InP-shell nanowires exceeds the intensity of pure InAs nanowires. It means that surface passivation can reduce an effect of surface states in nanowires on their optical properties.