Efficient single-mode fiber-optic module

A study was made of the optimal conditions for coupling a laser beam (λ = 1.3 μm) with a slight ellipticity of its transverse cross section into a single-mode fiber waveguide. The coupling was performed by a hemispherical microlens formed from a cone-tapered end of a fiber waveguide. The maximum coupling efficiency achieved in these experiments was 78%, against the theoretically possible value of 89%. A fiber-optic module enduring rigid stable connection of a laser to a single-mode fiber waveguide was constructed.