High efficiency partial distributed feedback (p-DFB) laser
View Patent ↗A second-order multi-mode partial distributed feedback (p-DFB) laser having increased electrical-to-optical power conversion efficiency, stabilized wavelength and narrowed emission linewidth. The laser includes an abbreviated grating housed in the laser cavity that is separated from both the front-end and the back-end of the laser facets.
1. An edge emitting semiconductor laser comprising:
a front facet,
a rear facet, which defines, together with the front facet, a laser cavity;
a partial grating having at least one edge, the edge of the partial grating located in the laser cavity at a distance x from the rear facet approximately defined by range:
λ
2
8
n
g
Δ
λ
<
x
<
L
5
where Δλ is a maximum allowed wavelength variation caused by interfering facet reflections, n g ≈4 the group index, λ is the vacuum wavelength and L is the length of the grating.
2. The laser of claim 1 , wherein the length of the partial grating is defined by:
λ
2
2
n
g
Δ
λ
<
L
DFB
<
L
5
.
3. The laser of claim 1 , wherein the partial grating has a length of less than about 90%-of the length of the laser cavity.
4. The laser of claim 3 , wherein the partial grating has a length less than about 50% of the length of the laser cavity.