Dual junction fiber-coupled laser diode and related methods
A laser diode apparatus has a first waveguide layer including a gain region connected in series with a second waveguide layer with a second gain region. A tunnel junction is positioned between the first and second guide layers. A single collimator is positioned in an output path of laser beams emitted from the first and second waveguide layers. The optical beam from the single collimator may be coupled into an optical fiber.
1. A laser diode apparatus comprising:
a first waveguide in a first row connected in series with a second waveguide in a second, adjacent row in a single epitaxial structure;
a single tunnel junction positioned between and in direct contact with the first and second waveguides, wherein the single tunnel junction comprises first and second heavily doped layers positioned in immediate, direct contact with one another, wherein the first and second heavily doped layers are in immediate, direct contact with an n-type cladding layer and a p-type cladding layer, and wherein a separated distance of the first and second waveguides is equal to a thickness of the single tunnel junction; and
a single collimator positioned in an immediate output path of laser beams emitted from both the first and second waveguides in the first and second rows, whereby the laser beams emitted from the first and second waveguides in the first and second rows are collimated initially using only the single collimator.
2. The laser diode apparatus of claim 1 , wherein an optical output of the single collimator is directed into an optical fiber.
3. The laser diode apparatus of claim 2 , further comprising a corrective optical assembly positioned between the single collimator and the optical fiber, wherein the corrective optical assembly receives the optical output of the single collimator and an optical output of the corrective optical assembly is directed into the optical fiber, wherein the corrective optical assembly comprises:
a second collimator;
a corrective optic device; and
a focusing lens.
4. The laser diode apparatus of claim 3 , wherein the single collimator is a fast-axis collimator and the second collimator is a slow-axis collimator.
5. The laser diode apparatus of claim 1 , wherein at least one of the first and second waveguides further comprises:
first and second cladding layers;
first and second guide layers positioned between the first and second cladding layers; and
an active layer positioned between the first and second guide layers.
6. The laser diode apparatus of claim 1 , wherein each of the first and second heavily doped layers of the single tunnel junction has a thickness dimension of substantially between 10-40 nm.
7. The laser diode apparatus of claim 1 , wherein the first heavily doped layer of the single tunnel junction further comprises a n++ layer and the second heavily doped layer of the single tunnel junction further comprises a p++ doped layer.
8. The laser diode apparatus of claim 7 , wherein a n-type cladding layer of the first waveguide is positioned in contact with the n++ layer and a p-type cladding layer of the second waveguide is positioned in contact with the p++ layer.
9. The laser diode apparatus of claim 1 , wherein the single collimator is centered between the first and second waveguides on the single epitaxial structure.
10. The laser diode apparatus of claim 1 , wherein the single collimator is positioned at a horizontal edge of the single epitaxial structure.