LARGE OPTICAL CAVITY (LOC) LASER DIODE HAVING QUANTUM WELL OFFSET AND EFFICIENT SINGLE MODE LASER EMISSION ALONG FAST AXIS
Laser diodes are configured to suppress lasing of a first and higher order modes along a fast axis of an optical beam emitted by the laser diode. An optical cavity is defined by a p-side of the laser diode, an n-side of the laser diode, and an active region located between the p- and n-sides. The n-side has an n-waveguide layer forming at least a portion of a waveguide having a quantum well offset towards the p-side. According to some embodiments, double cladding layers out-couple higher order modes. According to other embodiments, double waveguides (e.g., symmetric and asymmetric) reduce gain applied to higher order modes.
1 . A laser diode configured to suppress lasing of a first and higher order modes along a fast axis of an optical beam emitted by the laser diode, the laser diode comprising:
an optical cavity defined by a p-side of the laser diode, an n-side of the laser diode, and an active region located between the p- and n-sides, the n-side including an n-waveguide layer forming at least a portion of a waveguide having a quantum well offset towards the p-side; and
adjacent cladding layers on one or both of the p- and n-sides, the adjacent cladding layers including outer and inner cladding layers, the inner cladding layer situated between and adjacent to the waveguide and the outer cladding layer, the outer and inner cladding layers having, respectively, first and second indices of refraction, the first index of refraction of the outer cladding layer being greater than the second index of refraction of the inner cladding layer and greater than an effective index of refraction of the first order mode so as to out-couple it from the waveguide.
2 . The laser diode of claim 1 , in which the n-side includes the adjacent cladding layers.
3 . The laser diode of claim 1 , in which the p-side includes the adjacent cladding layers.
4 . The laser diode of claim 1 , in which the p-side includes a p-cladding layer adjacent the active region such that the n-waveguide comprises substantially an entire portion of the waveguide.
5 . The laser diode of claim 1 , further comprising a graded-index refractive index profile adjacent to the active region.
6 . The laser diode of claim 1 , further comprising a stepped-index refractive index profile adjacent to the active region.
7 . The laser diode of claim 4 , further comprising an asymmetric graded-index refractive index profile adjacent to the active region.
8 . The laser diode of claim 4 , further comprising an asymmetric stepped-index refractive index profile adjacent to the active region.
9 . A diode laser assembly including a laser diode of claim 1 .
10 . A laser diode configured to suppress lasing of a first and higher order modes along a fast axis of an optical beam emitted by the laser diode, the laser diode comprising:
an optical cavity defined by a p-side of the laser diode, an n-side of the laser diode, and an active region located between the p- and n-sides; and
a set of n-waveguide layers on the n-side that form at least a portion of a double waveguide, the set of n-waveguide layers including outer and inner n-waveguide layers in which optical gain applied to the first and higher order modes is reduced relative to optical gain applied to a fundamental mode.
11 . The laser diode of claim 10 , in which the inner n-waveguide layer situated between and adjacent to the active region and the outer n-waveguide layer, the outer and inner n-waveguide layers having, respectively, first and second indices of refraction, the first index of refraction of the outer n-waveguide layer being less than the second index of refraction of the inner n-waveguide layer.
12 . The laser diode of claim 10 , in which the double waveguide has an asymmetric refractive index.
13 . The laser diode of claim 10 , further comprising adjacent n-cladding layers, the adjacent n-cladding layers including outer and inner cladding layers, the inner cladding layer situated between and adjacent to the outer n-waveguide layer and the outer cladding layer, the outer and inner cladding layers having, respectively, first and second indices of refraction, the first index of refraction of the outer cladding layer being greater than the second index of refraction of the inner cladding layer and greater than an effective index of refraction of the first order mode so as to out-couple it from at least the inner n-waveguide layer.
14 . The laser diode of claim 10 , in which the set of n-waveguide layers form at least a portion of a symmetric waveguide having matching indices of refraction and being separated by a cladding layer having an index of refraction that is less than that of the set of n-waveguide layers.
15 . The laser diode of claim 14 , in which the cladding layer is offset to the n-side such that a first portion of the double waveguide is wider than a second portion of the double waveguide, the first portion including the inner n-waveguide and p-waveguide layers, and the second portion including the outer n-waveguide layer.
16 . A diode laser assembly including a laser diode of claim 10 .