Patent ID: 8520990

Claim:
A collimating lens assembly having a longitudinal axis, consisting of: a singlemode fiber terminating in a distal end; a step-index multimode fiber having a proximal end abutting said singlemode fiber distal end, and having a distal end, said step-index multimode fiber being arranged to reduce the optical energy at said step-index multimode fiber distal end from that at said step-index multimode fiber proximal end; a graded-index multimode fiber having a proximal end abutting said step-index multimode fiber distal end, and having a distal end, said graded-index multimode fiber being arranged to reduce the optical energy at said graded-index multimode fiber distal end from that at said grade-index multimode fiber proximal end; and a collimating lens longitudinally spaced from said graded-index multimode fiber distal end, and operatively arranged to collimate light rays emanating from said graded-index multimode fiber distal end; and wherein all elements having a temperature-dependent refractive index are omitted from the optical path between said singlemode fiber distal end and said collimating lens such that said collimating lens assembly is capable of handling energy levels in said singlemode fiber that are typically used for wavelength division multiplexing.