We characterize a semiconductor external cavity diode laser whose optical feedback is provided by a guided mode resonance filter (GMRF). We focus on the spectral properties. The wavelength of operation falls in the telecom range (1506 nm). The GMRF acting both as a wavelength intracavity filter and feedback mirror allows for a compact laser design. The single-mode operation is verified in a wide range of driving currents. We finely tune the cavity length to adjust the frequency by 14 GHz without mode-hops in agreement with the expected free-spectral range of the resonator ∼20 GHz. The compactness of the cavity allows fast frequency sweeps when modulating the current (90 MHz/mA at 100 kHz, the modulation bandwidth). The frequency noise (366 kHz whitenoise contribution) is also analysed to evaluate the potential of our design for high-resolution applications.