Manufacturable sampled grating mirrors
View Patent ↗The present invention relates to the tailoring the reflectivity spectrum of a sampled-grating distributed Bragg reflector (SGDBR) by applying digital sampling theory to choose the way each reflector is sampled. The resulting mirror covers a larger wavelength span and has peaks with a larger, more uniform, coupling constant (κ) than the mirrors produced using conventional approaches. The improved mirror also retains the benefits of the sample grating approach. Additionally, most of the embodiments are relatively simple to manufacture.
1. A method for configuring a sampled grating distributed Bragg reflector for use in a laser having an output within a specific wavelength band, the method comprising the steps of:
(a) selecting a preferred κ for a plurality of wavelengths in the specific wavelength band that is to be used;
(b) selecting a preferred wavelength tuning range for said reflector; and
(c) generating a sampling function that, when applied to the reflector, results in a substantially close fit to the preferred κ within the preferred wavelength tuning range;
wherein the sampling function produces a sampled grating including a plurality of sampled grating portions each having a first grating phase and a second grating phase, the sampled grating portions separated from each other by portions with no grating.
2. The method of claim 1 , further comprising the step of sampling the reflector in accordance with the sampling function.
3. The method of claim 1 , wherein the portions with no grating occupy more than 70% of the reflector.
4. A method for configuring a sampled grating distributed Bragg reflector for use in a laser having an output within a specific wavelength band, the method comprising the steps of:
(a) selecting a preferred wavelength tuning range for said reflector:
(b) determining a desired average κ for a plurality of wavelengths of the specific wavelength band that is to be used: and
(c) generating a sampling function that, when applied to the reflector, results in a substantially close fit to the desired average κ within the preferred tuning range;
wherein the sampling function produces a sampled grating including a plurality of sampled grating portions each having a first grating phase and a second grating phase, the sampled grating portions separated from each other by portions with no grating.
5. The method of claim 4 ,further comprising the step of sampling the reflector in accordance with the sampling function.
6. The method of claim 4 , wherein the portions with no grating occupy more than 70% of the reflector.
7. A method for configuring a sampled grating distributed Bragg reflector for use in a laser having an output within a specific wavelength band, the method comprising the steps of:
(a) selecting a preferred κ for a plurality of wavelengths within the specific wavelength band that is to be used;
(b) selecting a preferred wavelength tuning range for said reflector;
(c) generating a sampling function that produces a sampled grating including a plurality of sampled grating portions having a first grating phase separated from each other by portions with no grating; and
(d) adding a first grating burst portion having a second grating phase different from the first grating phase at the beginning of a first sampled grating portion of the sampled grating;
wherein the reflector results in a substantially close fit to the preferred κ within the preferred wavelength tuning range.
8. The method of claim 7 , wherein the portions with no grating occupy more than 70% of the reflector.
9. The method of claim 7 , wherein the second grating phase is substantially opposite that of said first grating phase of said sampled grating.
10. The method of claim 7 , wherein the first grating burst portion is spaced apart from the first sampled grating portion by a spacing with no grating.
11. A method for configuring a sampled grating distributed Bragg reflector for use in a laser having an output within a specific wavelength band, the method comprising the steps of:
(a) selecting a preferred wavelength tuning range for said reflector;
(b) determining a desired average κ for a plurality of wavelengths of the specific wavelength band that is to be used;
(c) generating a sampling function that produces a sampled grating including a plurality of sampled grating portions having a first grating phase separated from each other by portions with no grating; and
(d) adding a first grating burst portion having a second grating phase different from the first grating phase at the beginning of a first sampled grating portion of the sampled grating;
wherein the reflector results in a substantially close fit to the preferred κ within the preferred wavelength tuning range.
12. The method of claim 11 , wherein the portions with no grating occupy more than 70% of the reflector.
13. The method of claim 11 , wherein the first grating burst portion is spaced apart from the first sampled grating portion by a spacing with no grating.
14. The method of claim 11 , wherein the first grating burst portion is spaced apart from the first sampled grating portion by a spacing with no grating and the second grating phase is substantially opposite that of said first grating phase of said sampled grating.
15. The method of claim 11 , wherein the second grating phase is substantially opposite that of said first grating phase of said sampled grating.
16. The method of claim 1 , wherein the sampling function reverses the grating phase at a beginning and an end of each sampled grating portion.
17. The method of claim 7 , wherein the first grating burst portion is spaced apart from the first sampled grating portion by a spacing with no grating and the second grating phase is substantially opposite that of said first grating phase of said sampled grating.
18. The method of claim 4 , wherein the sampling function reverses the grating phase at a beginning and an end of each sampled grating portion.