Laser-processed grin lenses and optical interface devices and assemblies using same

A method of forming a gradient-index (GRIN) lens, comprising:

• drawing a cylindrical GRIN cane having a polynomial or parabolic GRIN index profile, to form a cylindrical GRIN rod that defines a central section with an outer surface, the central section having a diameter D1 in the range of 200 micrometers≦D1≦420 micrometers, where the central section index profile nA(r) is given by nA(r)=n0(1−2Δ(r/r1)α)1/2, where Δ=(n02−nC2)/2/n02, where α is between 1.8 and 2.1, and n0 and nC are constants;
• cladding the cylindrical GRIN rod outer surface with an annular cladding having a radial width δr in the range of 5 micrometers≦δr≦50 micrometers;
• and
• laser cleaving the coated cylindrical GRIN rod to form a GRIN lens element, wherein the central section has a front planar surface defined by said laser cleaving and the annular cladding has a curved annular front surface defined by said laser cleaving.

A GRIN lens assembly, comprising:

• a monolithic transparent medium;
• at least one GRIN lens central section supported in the monolithic transparent medium, the GRIN lens central section having an outer surface, a front end that is planar, and having a diameter D1 in the range of 200 micrometers≦D1≦420 micrometers, where the central section index profile nA(r) is given by nA(r)=n0 (1−2Δ(r/r1)α)1/2, where Δ=(n02−nC2)/2/n02, where a is between 1.8 and 2.1, and n0 and nC are constants;
• and
• an annular cladding that surrounds the outer surface of the central section of the GRIN lens and that has an annular front surface and a radial width δr such that a surface curvature caused by a laser cleaving process resides substantially entirely on the annular front surface.

A gradient-index (GRIN) lens assembly, comprising:

• a cylindrical section having a polynomial or parabolic GRIN index profile nA(r), planar front and back surfaces, an outer surface, and a diameter D1 in the range of 200 micrometers≦D1≦420 micrometers;
• an annular cladding of outer diameter D2 surrounding the central section outer surface and having front and back annular surfaces and either a constant or a varying refractive index where the central section index profile nA(r) is given by nA(r)=n0 (1−2Δ(r/r1)α)1/2, where Δ=(n02−nC2)/2/n02, where α is between 1.8 and 2.1, and n0 and nC are constants;
• and
• an optical fiber optically coupled to the central section at the planar back surface.