Patent ID: 7649917

Claim:
A method of providing a set of continuous tuning regions from a discontinuously tuned laser, the method comprising the steps of: providing a wavelength reference having at least first and second resonance peaks; sweeping the laser across a pre-determined wavelength range of the wavelength reference; defining, within the laser sweep, one or more regions of continuous tuning operation of the laser, each of the regions corresponding to a response of the laser between adjacent resonance peaks of the wavelength reference, wherein the regions of continuing tuning operation of the laser are defined by: calibrating the laser so as to provide a range of currents with no mode jumps; selecting continuous regions with a first frequency overlap that have a resonance peak of the wavelength reference from their beginnings and ends; and setting the currents whilst sweeping through those wavelengths so as to provide a smoothly transitioning wavelength sweep, wherein setting the currents is provided by filtering and/or shaping the currents; and assigning a frequency (F meas ) or wavelength (λ meas ) value to discrete points within the continuous region of operation of the laser device, the value being assigned by: measuring the time from the resonance peak at the beginning of the sweep to the measurement instant (T meas ), measuring the time required to sweep between adjacent resonance peaks (T segment ) and calculating the value by extracting a value for T meas from T segment .