A wavelength monitor based on a pair of tilted fiber Bragg gratings is reported. The monitor exhibits a subpicometer wavelength selectivity over a broad wavelength range (> 30 nm), and a low insertion loss (< 1 dB) for laser light with polarization matching the reference polarization of the device. Simulations show that a wavelength coverage up to 100 nm is possible and that the resolution degradation due to changes in the polarization state can be avoided by proper design of the gratings.