Abstract: A polarization-dependent Faraday isolator, imposing both non-reciprocal and reciprocal polarization rotation, implements the polarizing and polarization-rotating optical elements as a solid block with coatings. The solid block includes a Faraday crystal. A forward-propagating laser beam enters the solid block via an input surface, undergoes total internal reflection at a side surface, and leaves the solid block via an output surface. Polarizing input- and output-coatings are disposed on the input and output surfaces, respectively. A phase-shifting coating is disposed on the first side surface and introduces a phase shift between s-polarized and p-polarized beam components of the forward-propagating laser beam during total internal reflection at the first side surface, resulting in reciprocal polarization rotation. The Faraday isolator can be made very compact and eliminates the need for separate alignment of the different optical elements.

Abstract: A multi-junction laser-diode module includes (a) a multi-junction laser diode having a plurality of laser junctions stacked in a vertical dimension parallel to the fast-axes of the laser beams emitted by the laser junctions, (b) a fast-axis cylindrical lens collimating each laser beam in the fast axis, whereby the laser beams emerge from the fast-axis cylindrical lens with mutually nonparallel propagation directions, (c) a transmissive beam-deflecting element that deflects the laser beams in the fast-axis dimension after the fast-axis cylindrical lens to make their propagation directions parallel, and (d) a slow-axis cylindrical lens configured to collimate each laser beam in the slow axis. The transmissive beam-deflecting element corrects for the propagation-direction discrepancy between the laser beams, in the fast-axis dimension, caused by fast-axis collimation. The multi-junction laser-diode module can thereby produce a laser beam bundle suitable for high-brightness fiber-coupling.

Abstract: A dual-substrate dichroic beam combiner includes two substrates, and a dichroic thin-film filter coated at a nominally planar interface between the substrates. The filter is configured to combine, into a combined laser beam, two input laser beams that are incident on the filter of the combiner from opposite respective sides thereof. One input beam is transmitted by the combiner, while the other input beam is reflected. The substrates are configured to, when heated by absorption of the input laser beams in the filter, form a lens for each of the input laser beams. The lens is either (a) a negative lens for each of the input laser beams or (b) a positive lens for each of the input laser beams. The combiner thereby reduces or eliminates focusing discrepancies between the two input beams, in the combined beam, as compared to a conventional single-substrate dichroic beam combiner.

Abstract: An optical isolator for generally collimated laser radiation includes a single polarizing element, at least one Faraday optical element, at least one reciprocal polarization altering optical element disposed at the single polarizing element, at least one reflective optical element for reflecting radiation to provide an even number of passes through the at least one Faraday optical element, and a magnetic structure. The magnetic structure is capable of generating a magnetic field within the at least one Faraday optical element that is generally aligned with the even number of passes along a beam propagation axis. The optical isolator is configured to receive generally collimated laser radiation, which passes through the single polarizing element and the at least one reciprocal polarization altering optical element and which makes at least two passes through the at least one Faraday optical element, whereby generally collimated laser radiation is output from the optical isolator.

Abstract: A connectorized fiber collimator includes a holder, a bearing, and a fiber collimator. The holder has a frontside, with a planar reference surface, and a backside. An outer circumferential surface of the holder defines a circular reference circumference. The frontside or backside has a recess. A through hole, at the recess, extends from the frontside to the backside. The bearing has a spherical surface seated in the recess. The fiber collimator is seated in a bore through the bearing. Rotation of the bearing in the recess adjusts pointing relative to a longitudinal axis of the connectorized fiber collimator. Lateral dimensions of the fiber collimator are undersized relative to the bore to facilitate offset adjustment relative to the longitudinal axis. Accurate alignment of the connectorized optical-fiber collimator in fiber-to-fiber and fiber-free-space couplings is achieved through mechanical registration of the planar reference surface and the circular reference circumference.

Abstract: A method for generating amplified laser radiation includes generating a forward-propagating laser beam in a first waveguiding gain stage, amplifying the forward-propagating laser beam in a second waveguiding gain stage, and directing the forward-propagating laser beam from an output waveguide of the first waveguiding gain stage to an input waveguide of the second waveguiding gain stage via a propagation path passing through a Kerr medium. The Kerr medium suppresses coupling, between the first and second waveguiding gain stages, of high-peak-power laser radiation exceeding a threshold intensity in the Kerr medium. Self-focusing in the Kerr medium causes a majority of the high-peak-power laser radiation to be outside at least one of an acceptance aperture and an acceptance angle of a receiving one of the output waveguide of the first waveguiding gain stage and the input waveguide of the second waveguiding gain stage. Each waveguiding gain stage may include a gain fiber.

Abstract: An optical isolator for use with high power, collimated laser radiation includes an input polarizing optical element, at least one Faraday optical element, at least two reflective optical elements for reflecting laser radiation to provide an even number of passes through said at least one Faraday optical element, at least one reciprocal polarization altering optical element, an output polarizing optical element, at least one light redirecting element for remotely dissipating isolated or lost laser radiation. The isolator also includes at least one magnetic structure capable of generating a uniform magnetic field within the Faraday optical element which is aligned to the path of the collimated laser radiation and a mechanical structure for holding said optical elements to provide thermal gradients that are aligned to the path of the collimated laser radiation and that provide thermal and mechanical isolation between the magnetic structure and the optical elements.

Abstract: An optical isolator for generally collimated laser radiation includes a single polarizing element, at least one Faraday optical element, at least one reciprocal polarization altering optical element disposed at the single polarizing element, at least one reflective optical element for reflecting radiation to provide an even number of passes through the at least one Faraday optical element, and a magnetic structure. The magnetic structure is capable of generating a magnetic field within the at least one Faraday optical element that is generally aligned with the even number of passes along a beam propagation axis. The optical isolator is configured to receive generally collimated laser radiation, which passes through the single polarizing element and the at least one reciprocal polarization altering optical element and which makes at least two passes through the at least one Faraday optical element, whereby generally collimated laser radiation is output from the optical isolator.

Abstract: An optical isolator for generally collimated laser radiation includes a single polarizing element, at least one Faraday optical element, at least one reciprocal polarization altering optical element disposed at the single polarizing element, at least one reflective optical element for reflecting radiation to provide an even number of passes through the at least one Faraday optical element, and a magnetic structure. The magnetic structure is capable of generating a magnetic field within the at least one Faraday optical element that is generally aligned with the even number of passes along a beam propagation axis. The optical isolator is configured to receive generally collimated laser radiation, which passes through the single polarizing element and the at least one reciprocal polarization altering optical element and which makes at least two passes through the at least one Faraday optical element, whereby generally collimated laser radiation is output from the optical isolator.

Abstract: An optical isolator for use with high power, collimated laser radiation includes an input polarizing optical element, at least one Faraday optical element, at least two reflective optical elements for reflecting laser radiation to provide an even number of passes through said at least one Faraday optical element, at least one reciprocal polarization altering optical element, an output polarizing optical element, at least one light redirecting element for remotely dissipating isolated or lost laser radiation. The isolator also includes at least one magnetic structure capable of generating a uniform magnetic field within the Faraday optical element which is aligned to the path of the collimated laser radiation and a mechanical structure for holding said optical elements to provide thermal gradients that are aligned to the path of the collimated laser radiation and that provide thermal and mechanical isolation between the magnetic structure and the optical elements.