Patent ID: 8548016

Claim:
A tunable laser system having fine and coarse wavelength discrimination, comprising: a first filter, disposed to receive a first portion of a first laser output from a first tunable laser, wherein the first laser output is swept over a first wavelength range, for providing a first series of pulses from the first portion of the first laser output over the first wavelength range, wherein the first filter has a first free spectral range (FSR), such that the pulses in the first series of pulses are separated in wavelength by the first FSR; a second filter, disposed to receive a second portion of the first laser output, for providing a second series of pulses from the second portion of the first laser output over the first wavelength range, wherein the second filter has a second FSR different from the first FSR, such that the pulses in the second series of pulses are separated in wavelength by the second FSR, and wherein the first FSR and the second FSR have a relative difference of less than about 20%; and a processing system for comparing the first series of pulses and the second series of pulses to identify a first series of markers, such that the markers in the first series of markers are separated in wavelength by a beat period of the first series of pulses and the second series of pulses when the first laser output is continuous in wavelength, wherein the first series of pulses provides fine wavelength discrimination and the first series of markers provides coarse wavelength discrimination.