A tunable laser system having fine and coarse wavelength discrimination is provided. The tunable laser system includes a first filter having a first free spectral range (FSR) and a second filter having a second FSR different from the first FSR. The first filter provides a first series of pulses from a first portion of a laser output, and a second filter provides a second series of pulses from a second portion of the laser output. A processing system compares the first series of pulses and the second series of pulses to identify a series of markers, in which the markers are separated by a beat period of the first series of pulses and the second series of pulses. Advantageously, the series of markers may be used for mode-hop detection and/or for wavelength referencing.