Accelerating the aging of multiple lasers
View Patent ↗A method of accelerating the aging of a laser to thereby determine the reliability of the laser. The method includes an act of providing a laser die for reliability testing, an act of applying a plurality of short signal pulses to the laser die so as to simulate the aging of the laser die, and an act of ascertaining the reliability of the laser die based on its response to the plurality of short signal pulses.
1. A method of accelerating the aging of multiple lasers to thereby determine the failure of the lasers, the method comprising:
providing a current source configured for supplying current in a plurality of short signal pulses;
providing a first plurality of laser structures for reliability testing, wherein the first plurality of laser structures include a first facet coating;
applying current from the current source to the first plurality of laser structures such that the first plurality of laser structures emit output light beams having an output power and optical intensity, the current being applied to the first plurality of laser structures in a plurality of short signal pulses so as to simulate the aging of the first plurality of laser structures;
ascertaining failure of the first plurality of laser structures based on their response to the plurality of short signal pulses;
providing a second plurality of laser structures for reliability testing, wherein the second plurality of laser structures include a second facet coating that is different from the first facet coating;
applying current from the current source to the second plurality of laser structures such that the second plurality of laser structures emit output light beams having an output power and optical intensity, the current being applied to the second plurality of laser structures in a plurality of short signal pulses so as to simulate the aging of the second plurality of laser structures;
ascertaining failure of the second plurality of laser structures based on their response to the plurality of short signal pulses; and
comparing failures of the first and second plurality of laser structures to determine which of the first and second facet coatings caused their respective plurality of laser structures to be operated for a longer period of time without failure.
2. The method in accordance with claim 1 , wherein the plurality of short signal pulses comprise a positive 2000 volt pulse and a negative 2000 volt pulse.
3. The method in accordance with claim 1 , wherein ascertaining failure of the first and second plurality of lasers comprises:
determining the amount of current that causes the first and second plurality of laser structures to become inoperable.
4. The method in accordance with claim 1 , wherein ascertaining failure of the first and second plurality of lasers comprises:
determining the Catastrophic Optical Damage (COD) threshold intensity for the first and second plurality of laser structures.
5. The method in accordance with claim 1 , wherein the first and second plurality of laser structures are Fabry-Perot (FP) laser structures.
6. The method in accordance with claim 1 , wherein the first and second plurality of laser structures are DFB laser structures.
7. The method in accordance with claim 6 , wherein the first and second plurality of laser structures each comprise:
a substrate;
a mode modifier layer positioned above the substrate;
a buffer layer positioned above the mode modifier layer;
a first confinement layer positioned above the buffer layer;
a second confinement layer positioned above the first confinement layer and below an active region;
a third confinement layer positioned above the active region;
a fourth confinement layer positioned above the third confinement layer;
a first spacer layer positioned above the fourth confinement layer;
an etch stop layer positioned above the first spacer layer;
a second spacer layer positioned above the etch stop layer;
a grating layer positioned above the second spacer layer; and
a top layer positioned above the grating layer and below a mesa.
8. The method in accordance with claim 1 , wherein the plurality of short signal pulses include an amplitude and a width that are the same.
9. The method in accordance with claim 1 , wherein the plurality of short signal pulses include an amplitude that is varied and a width that is fixed.
10. The method in accordance with claim 1 , wherein the plurality of short signal pulses include a width that is varied and an amplitude that is fixed.
11. The method in accordance with claim 1 , wherein the plurality of short signal pulses include an amplitude and a width that are both varied.
12. The method in accordance with claim 1 , wherein each pulse has a width less than or equal to about 2 milliseconds.
13. The method in accordance with claim 1 , wherein the plurality of short signal pulses of current results in a larger amount of current to be applied to the first and second plurality of laser structures compared to a continuous wave.
14. The method in accordance with claim 13 , wherein the plurality of short signal pulses of current results in less heat to be applied to the first and second plurality of laser structures compared to a continuous wave.
15. The method in accordance with claim 13 , wherein the plurality of short signal pulses of current results in a larger amount of optical power output from the first and second plurality of laser structures compared to a continuous wave.
16. The method in accordance with claim 1 , wherein the method is devoid of:
heating the first or second plurality of laser structures in an oven; and/or
causing thermal roll-over.