DBR laser diode with symmetric aperiodically shifted grating phase
View Patent ↗In accordance with one embodiment of the present disclosure, a DBR laser diode is provided where the wavelength selective grating of the laser diode is characterized by an aperiodically shifted grating phase φ and a Bragg wavelength λ B . The aperiodically shifted grating phase φ is substantially symmetric or substantially π-shifted symmetric relative to a midpoint C L or shifted midpoint C L * of the DBR section. The phase φ of the wavelength selective grating is characterized by aperiodic phase jumps of magnitude φ J1, J2, . . . and segment lengths l 0, 1, . . . . The phase jumps of the wavelength selective grating are arranged substantially symmetrically about a midpoint C L or shifted midpoint C L * of the DBR section along the optical axis of the DBR laser diode. At least two phase jumps reside on each side of the midpoint C L or shifted midpoint C L * of the DBR section.
1. A DBR laser diode comprising a DBR section and a gain section, wherein:
the DBR section comprises a wavelength selective grating;
the wavelength selective grating is characterized by an aperiodically shifted grating phase φ and a Bragg wavelength λ B ;
the aperiodically shifted grating phase φ is substantially symmetric or substantially π-shifted symmetric relative to a midpoint C L or shifted midpoint C L * of the DBR section along the optical axis of the DBR laser diode;
the phase φ of the wavelength selective grating is characterized by aperiodic phase jumps of magnitude φ J1, J2, . . . and segment lengths l 0, 1, . . . ;
the phase jumps of the wavelength selective grating are arranged substantially symmetrically about a midpoint C L or shifted midpoint C L * of the DBR section along the optical axis of the DBR laser diode; and
at least two phase jumps reside on each side of the midpoint C L or shifted midpoint C L * of the DBR section.
2. A DBR laser diode as claimed in claim 1 wherein:
the aperiodically shifted grating phase φ is substantially symmetric relative to a midpoint C L of the DBR section along the optical axis of the DBR laser diode.
3. A DBR laser diode as claimed in claim 1 wherein:
the aperiodically shifted grating phase φ is substantially symmetric relative to a shifted midpoint C L * of the DBR section along the optical axis of the DBR laser diode.
4. A DBR laser diode as claimed in claim 1 wherein:
the aperiodically shifted grating phase φ is substantially π-shifted symmetric relative to a midpoint C L of the DBR section along the optical axis of the DBR laser diode.
5. A DBR laser diode as claimed in claim 1 wherein:
the aperiodically shifted grating phase φ is substantially π-shifted symmetric relative to a shifted midpoint C L * of the DBR section along the optical axis of the DBR laser diode.
6. A DBR laser diode as claimed in claim 1 wherein:
the aperiodically shifted grating phase φ is substantially symmetric or π-shifted symmetric relative to a shifted midpoint C L * of the DBR section along the optical axis of the DBR laser diode; and
the spatial shift of the center of the shifted midpoint C L *, relative to the midpoint C L is less than approximately one-tenth of the grating length.
7. A DBR laser diode as claimed in claim 1 wherein each segment length l 0 , l 1, . . . is less than approximately 100 μm.
8. A DBR laser diode as claimed in claim 1 wherein the segment lengths l 0 , l 1, . . . collectively define a distribution with standard deviation of approximately 20 μm±10%.
9. A DBR laser diode as claimed in claim 1 wherein the segment lengths l 0 , l 1, . . . collectively define a wavelength selective grating length L DBR that is between approximately 600 μm and approximately 750 μm.
10. A DBR laser diode as claimed in claim 1 wherein the substantially symmetric aperiodically shifted grating phase φ is characterized by a substantially square or trapezoidal profile.
11. A DBR laser diode as claimed in claim 1 wherein the depth of successive phase jumps varies along the optical axis of the DBR laser diode.
12. A DBR laser diode as claimed in claim 1 wherein:
the DBR laser diode is combined with a wavelength conversion device to form a frequency up-converted laser source; and
the wavelength conversion device is characterized by multiple phase-matching conversion peaks allowing frequency up-conversion of the reflectivity peaks of the wavelength selective grating of the DBR section through second-harmonic and/or sum-frequency generation.
13. A DBR laser diode as claimed in claim 1 wherein each phase jump has a complementary phase jump of substantially equal magnitude and each constant-phase segment has a complementary constant-phase segment of substantially equal segment length on an opposite side of the midpoint C L or shifted midpoint C L * of the DBR section.
14. A DBR laser diode as claimed in claim 1 wherein the Bragg wavelength λ B , the phase jumps φ J1 , φ J2 , φ J3 , and φ J4 , and the segment lengths l 0 , l 1 , l 2 , l 3 , l 4 , l 5 are such that the wavelength selective grating exhibits two dominant reflectivity peaks.
15. A DBR laser diode as claimed in claim 14 wherein the two dominant reflectivity peaks take the form of sidebands S 1 , S 2 about a central Bragg wavelength λ B of the grating.
16. A DBR laser diode as claimed in claim 14 wherein the two dominant reflectivity peaks are separated by at least about 1.6 nm.
17. A DBR laser diode as claimed in claim 14 wherein respective maxima of the two dominant reflectivity peaks are approximately equal.
18. A DBR laser diode comprising a DBR section and a gain section, wherein:
the DBR section comprises a wavelength selective grating;
the wavelength selective grating is characterized by an aperiodically shifted grating phase φ and a Bragg wavelength λ B ;
the aperiodically shifted grating phase φ is substantially symmetric or substantially π-shifted symmetric relative to a midpoint C L or shifted midpoint C L * of the DBR section along the optical axis of the DBR laser diode;
the phase φ of the wavelength selective grating is characterized by aperiodic phase jumps of magnitude φ J1, J2, . . . and segment lengths l 0, 1, . . . ;
each segment length l 0, 1, . . . is less than approximately 100 μm and the segment lengths l 0, 1, . . . collectively define a wavelength selective grating length L DBR that is between approximately 600 μm and approximately 750 μm;
at least two phase jumps reside on each side of the midpoint C L or shifted midpoint C L * of the DBR section;
each phase jump has a complementary phase jump of substantially equal magnitude and each constant-phase segment has a complementary constant-phase segment of substantially equal segment length on an opposite side of the midpoint C L or shifted midpoint C L * of the DBR section;
the Bragg wavelength λ B , the phase jumps φ J1 , φ J2 , φ J3 , and φ J4 , and the segment lengths l 0 , l 1 , l 2 , l 3 , l 4 , l 5 are such that the wavelength selective grating exhibits a plurality of dominant reflectivity peaks in the form of sidebands S 1 , S 2 , etc. about a central Bragg wavelength λ B of the grating; and
the two sidebands closest to the central Bragg wavelength λ B of the grating are separated by at least about 1.6 nm.