Broad area diode laser with high efficiency and small far-field divergence
A broad area laser, with high efficiency and small far-field divergence, has an active layer, a first contact and a second contact, each having a width larger than 10 μm. An anti-wave guiding layer, which is positioned laterally with respect to the active region, is enclosed between the first and second contacts, wherein a refractive index of the anti-wave guiding layer is larger than a minimum refractive index of cladding layers. A minimum distance between the anti-wave guiding layer and a projection of one of the contacts on the plane of the anti-wave guiding layer is between 0 and 100 μm.
1. A diode laser, comprising:
a first contact for the injection of charge carriers,
a first cladding layer, wherein the first contact contacts the first cladding layer,
a first wave guiding layer arranged on the first cladding layer,
an active layer suitable for emitting radiation, said active layer being arranged on the first wave guiding layer,
a second wave guiding layer arranged on the active layer, and
a second cladding layer arranged on the second wave guiding layer, and
a second contact for the injection of charge carriers, wherein the second contact contacts the second cladding layer, and wherein the active layer,
the first contact and the second contact each extend at least partially between an emitting facet and a reflecting facet,
wherein the active layer, the first contact and the second contact each have a width larger than 10 μm, and that an anti-wave guiding layer is positioned outside the active region enclosed between the contacts, wherein the refractive index of the anti-wave guiding layer is larger than the minimum refractive index of the cladding layers, and wherein the minimum distance between the anti-wave guiding layer and a projection of one of the contacts on the plane of the anti-wave guiding layer lies between 0 and 100 μm.
2. The diode laser of claim 1 , wherein the anti-wave guiding layer is positioned completely outside the active region enclosed between the contacts.
3. The diode laser of claim 1 , wherein the thickness of the anti-wave guiding layer and the refractive index of the anti-wave guiding layer meet the condition (1):
| n 1 eff −n 2 eff |<0.15 (1)
wherein n 1 eff is the effective refractive index in the active region and n 2 eff is the effective refractive index in the region of the anti-wave guiding layer.
4. The diode laser of claim 1 , wherein the thickness of the anti-wave guiding layer and the refractive index of the anti-wave guiding layer meet the condition (2):
| n 1 eff −n 2 eff <0.10. (2)
5. The diode laser of claim 1 , wherein the thickness of the anti-wave guiding layer and the refractive index of the anti-wave guiding layer meet the condition (3):
| n 1 eff −n 2 eff |<0.05. (3)
6. The diode laser of claim 1 , wherein the minimum distance between the active layer and the anti-wave guiding layer is smaller than or equal to the sum of the thickness of the first cladding layer and the thickness of the first wave guiding layer.
7. The diode laser of claim 1 , wherein the minimum distance between the active layer and the anti-wave guiding layer is smaller than the sum of the thickness of the second cladding layer and the thickness of the second wave guiding layer.
8. The diode laser of claim 1 , wherein the first cladding layer and the first wave guiding layer are n-conducting and the second cladding layer and the second wave guiding layer are p-conducting, wherein the minimum distance between the active layer and the anti-wave guiding layer amounts to between 40% and 100% of the thickness of the second wave guiding layer.
9. The diode laser of claim 1 , wherein the minimum distance between the anti-wave guiding layer and a projection of one of the contacts on the plane of the anti-wave guiding layer lies between 0 and 50 μm.
10. The diode laser of claim 1 , wherein the minimum distance between the anti-wave guiding layer and a projection of one of the contacts on the plane of the anti-wave guiding layer lies between 10 and 50 μm.
11. The diode laser of claim 1 , wherein the active layer, the first contact and the second contact each have a width between 20 and 800 μm.
12. The diode laser of claim 1 , wherein the active layer, the first contact and the second contact each have a width between 30 and 400 μm.
13. The diode laser of claim 1 , wherein the anti-wave guiding layer is made of germanium or gallium arsenide.