Method for finding and tracking single-mode operation point of external cavity diode lasers

1. A method comprising the following steps:

(a) determining if a laser is operating in a single-mode state, the laser having a laser current, a laser temperature, and an output light having a wavelength;

(b) if the laser is determined to not be operating in a single-mode state in step (a), determining a degree to which one or more tunable parameters for the laser must be adjusted so that the laser operates in a single-mode state if not operating in a single-mode state, wherein the one or more tunable parameters is selected from the group consisting of the laser current, the laser temperature, and the wavelength of the output light;

(c) adjusting the one or more tunable parameters of the laser by an amount determined in step (b);

(d) determining if one or more measured parameters of the laser are within a desired range after the adjustment made in step (c), wherein the one or more measured parameters include laser output power and laser wavelength;

(e) if the one or more measured parameters are determined in step (d) to not be within the desired range, determining a new adjustment to the one or more tunable parameters for placing the one or more measured parameters within the desired range;

(f) performing the new adjustment to the one or more tunable parameters according to the determination of step (e); and

(g) repeating steps (a) through (f) until the laser is operating in a single-mode state and the one or more measured parameters are within the desired range.

2. The method of claim 1 , wherein the one or more tunable parameters includes the laser current.

3. The method of claim 2 , further comprising determining a current range for a single-mode plateau for a single current sweep for the laser and setting the laser current at a midpoint of the current range for the single-mode plateau.

4. The method of claim 3 , wherein the single-mode plateau is a widest single-mode plateau for the single current sweep.

5. The method of claim 2 , further comprising determining a current range for an overlapping single-mode plateau for two or more current sweeps for the laser and setting the laser current at a midpoint of the current range for the single-mode plateau.

6. The method of claim 5 , wherein the overlapping single-mode plateau is a widest overlapping single-mode plateau for the two or more current sweeps.

7. The method of claim 5 , wherein at least one of the current sweeps is an up sweep and at least one of the current sweeps is a down sweep.

8. The method of claim 1 , wherein the tunable parameter includes the wavelength of the output light.

9. The method of claim 8 , wherein step (c) comprises bumping the wavelength of the output light by a wavelength step if the laser output power cannot be set to selected power due to mode hops causing the laser output power to fluctuate beyond a specified range.

10. The method of claim 1 , wherein the one or more tunable parameters includes the laser current and the wavelength of the output light.

11. The method of claim 1 , wherein the laser is a diode laser.

12. The method of claim 1 , wherein the laser is an external cavity laser.

13. The method of claim 12 , wherein the laser is an external cavity laser diode.