Patent ID: 7251259

Claim:
Optical apparatus comprising: a diode-laser emitter arranged to emit an output beam along a propagation axis, said diode-laser having fast axis, and a slow axis perpendicular to each other and perpendicular to said propagation axis, said beam having a first divergence in said fast axis and a second divergence in said slow axis, said second divergence being less than said first divergence, and said diode-laser having a gain-bandwidth; a lens disposed on said propagation axis of said diode-laser, said lens configured and aligned with said diode-laser such that said output beam is transmitted by said lens collimated in said fast axis and with said slow axis divergence unchanged; a length of optical fiber arranged to receive said transmitted output beam, said optical fiber having a core surrounded by a first cladding, said first cladding being surrounded by a second cladding, said first cladding having a lower refractive index than that of said core, and said second cladding having a lower refractive index than that of said first cladding; said core including a wavelength-selective Bragg grating and having an elongated cross-section, said cross-section having a width selected such that said core functions as a low-mode core in said width direction of said cross section; wherein said length direction of said core is aligned with said fast axis of said diode-laser and wherein said diode-laser has a gain-bandwidth and said Bragg Grating has a reflection bandwidth less than said gain bandwidth and has a peak reflectivity within said gain-bandwidth.