Wide strip diode laser employing a lens
AssigneeAT&T Bell Laboratories
InventorTheodore Sizer, II
Life of this patent
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Abstract
An improved diode laser is attained by augmenting the conventional diode laser structure with a cylindrical lens that arrests the divergence of the beam in the spatial direction where it is rapidly diverging. To properly arrest the divergence of the beam and to thereby circularize it, the cylindrical lens is placed at a point in space where the size of the laser beam in the two orthogonal spatial directions is substantially the same. With proper selection of the lens' focal length, the nearly circular cross section of the light is maintained as it travels away from the diode laser. The diode laser is further improved by making the diode structure facet that is closest to the lens highly transmissive, and forming a partially reflective facet on the otherside of the lens. The elongates the resonance cavity.
Claims12
An external cavity diode laser having a broad quantum wells strip between a first facet, which is at least partially reflective, and a second facet parallel to said first facet, strip appears at the second facet with a cross section having a long measure along a first axis and a short measure along a second axis that is perpendicular to the first axis, and a focusing means having a columnar portion with a long dimension along a longitudinal axis and a cross section perpendicular to the longitudinal axis that arrest divergence of light along said second axis, situated in proximity to said second facet with its longitudinal axis parallel to said first axis, characterized in that
- a principal plane of said focusing means, lying in the plane of said first axis and said second axis, is situated approximately at a distance d.sub.c from said second facet, with d.sub.c being the distance from said second facet where the girth of a light beam emanating from said optically emitting area is substantially the same in the direction of said first axis and said second axis.
An external cavity diode laser, comprising:
- a broad strip diode laser structure with a first planar facet that is at least partially reflective, a second planar facet that is highly transmissive, and a quantum wells strip extending between said first and second facets and perpendicular to said first facet;
- a third facet that is at least a partially reflective surface, and parallel to said first facet;
- and
- a columnar lens with its long axis parallel to the plane of said strip and to the planes of said first facet, interposed between said broad strip laser structure and said partially reflective surface, at a distance from said highly transmissive facet to a principal place of the columnar lens where the ratio of the beam size in the plane parallel to the strip to the beam size in the plane perpendicular to the strip is substantially 1.
Dependencies are inferred from the claim text.