Misalignment-tolerant total-internal-reflection fiber optic interface modules and assemblies with high coupling efficiency

A lens for coupling infrared light from a light source having a light-source axis to an optical fiber having an end and a core with a central axis that is substantially orthogonal to the light-source axis, the lens comprising along a lens axis:

• a lens body having a front lens surface with an aspherical shape and that constitutes an only surface having optical power and an only air interface for an optical path between the light source and the optical fiber;
• the lens body further comprising a planar rear lens surface against which the optical fiber end abuts, wherein the optical fiber is supported by an optical support feature configured as a groove;
• a total-internal-reflection (TIR) surface formed in the lens body between the front and rear lens surfaces that folds the lens axis so that the lens axis aligns with the orthogonal light source and central axes;
• and
• a back focus that resides within the optical fiber core at a back focus distance F2 from the end of the optical fiber.

An optical system comprising:

• a lens having a lens body with a lens axis, a front surface with an aspheric shape and that constitutes an only surface having optical power, and a planar rear surface, the lens body being substantially transparent to an infrared wavelength of light;
• a total-internal-reflection (TIR) surface formed in the lens body between the front and rear lens surfaces that folds the lens axis by substantially 90 degrees;
• an optical fiber having a core and an end, the optical fiber arranged with its end abutting the planar rear lens surface, with an optical support feature configured as a groove;
• a light source disposed substantially at a front focus distance away from the front lens surface, the light source being configured to emit light having an infrared wavelength;
• and
• a back focus that resides within the optical fiber core at the back focus distance F2 from the planar rear lens surface.

A fiber optic interface module configured to provide optical communication of infrared light between a plurality of light sources and a plurality of optical fibers each having an end and a core, comprising:

• a module body that is substantially transparent to the infrared light and that includes a top surface and a bottom surface, wherein the top surface defines a total-internal-reflection (TIR) mirror, an end wall, and optical fiber support features configured as grooves that operably support the plurality of optical fibers, with the optical fiber ends abutting the end wall;
• a plurality of lens surfaces formed on the bottom surface of the module body, wherein the lens surfaces, the TIR mirror, the end wall and intervening portions of the module body define a plurality of lenses each having a folded optical axis comprising a source optical path OP between the corresponding lens surface and the TIR mirror, wherein the lens surface of each respective optical path is the only surface of the respective optical path having optical power;
• and
• the lens surfaces each having a shape that provides a theoretical coupling efficiency CE≧85% between each light source and the corresponding optical fiber, the lens surfaces defining corresponding back focuses that fall within the optical fiber core of the corresponding optical fibers at respective back focus distances F2 from the end of the corresponding optical fibers when the optical fibers are operably supported one each in the optical fiber support features such that that the source optical path OPs of each lens of the plurality of lenses can be laterally offset from a light-source axis of a corresponding one of the plurality of light sources by a lateral misalignment.