Fiber laser amplification systems and methods are disclosed for use with a chirally coupled core (3C) optical fiber enabling the generation of a high-power output beam having a controlled stable polarization state. Vector modulation instabilities which typically induce undesirable sidebands in 3C fiber optics are greatly reduced even at high peak powers, enabling operation of the up to power levels limited mainly by stimulated Raman scattering (SRS). Polarization extinction ratios (PER) demonstrate long-term stability and minimal degradation due to changes in system temperature. Delays in reaching stable operation during start-up are also greatly reduced.

The present disclosure provides an optical waveguide design of a fiber modified with a thin layer of epsilon-near-zero (ENZ) material. The design results in an excitation of a highly confined waveguide mode in the fiber near the wavelength where permittivity of thin layer approaches zero. Due to the high field confinement within thin layer, the ENZ mode can be characterized by a peak in modal loss of the hybrid waveguide. Results show that such in-fiber excitation of ENZ mode is due to the coupling of the guided fundamental core mode to the thin-film ENZ mode. The phase matching wavelength, where the coupling takes place, varies depending on the refractive index of the constituents. These ENZ nanostructured optical fibers have many potential applications, for example, in ENZ nonlinear and magneto-optics, as in-fiber wavelength-dependent filters, and as subwavelength fluid channel for optical and bio-photonic sensing.

It is proposed to use a spun birefringent fiber for a current sensor or magnetic field sensor. The fiber has a birefringence that increases with temperature. In this case, the temperature dependence of the fiber's sensitivity to magnetic fields counteracts the temperature dependence of the fiber's Verdet constant, which allows to design current and field sensors that have reduced temperature dependence.

The present disclosure provides a pitch reducing optical fiber array or a multicore fiber including at least one chiral fiber grating incorporated therein that is operable to couple the modes in different fiber cores within a spectral range determined in some instances by the helical pitch of the corresponding chiral fiber grating.

An optical system includes an optical waveguide, and a first optical element configured to direct a first ray, having a first circular polarization and impinging on the first optical element at a first incidence angle, in a first direction so that the first ray propagates through the optical waveguide via total internal reflection toward a second optical element. The first optical element is configured to also direct a second ray, having a second circular polarization that is distinct from the first circular polarization and impinging on the first optical element at the first incidence angle, in a second direction that is distinct from the first direction so that the second ray propagates away from the second optical element. The second optical element is configured to direct the first ray propagating through the optical waveguide toward a detector.

A light source optical system includes: a first optical system configured to guide a first light beam having a first wavelength emitted from a light source to a wavelength conversion element; the wavelength conversion element configured to convert the first light beam into a second light beam having a second wavelength different from the first wavelength, and emit the second light beam; and a second optical system through which the second light beam emitted from the light conversion element passes. The second optical system includes a light guide element configured to guide a portion of the second light beam from one end surface of the light guide element to the other end surface of the light guide element to separate the portion of the second light beam from the second light beam.

A first waveguide core is configured to receive light via an input surface. The first waveguide core extends away from the input surface in a light propagation direction and terminates at a coupling region. A second waveguide core has a first end at the coupling region and a second end at a media-facing surface that is opposed to the input surface. The first end is separated from the termination of the first waveguide core by a gap in the coupling region. The coupling region includes an overlap between the first and second waveguide cores and is configured to promote evanescent coupling between the first and second waveguide cores.

Among other things, piezoelectric materials and methods of their manufacture are described; particularly methods of forming regions of varying crystal structure within a relaxor piezoelectric substrate. Such methods may including heating the piezoelectric substrate above the transition temperature and below the Curie temperature such that a first phase transition occurs to a first crystal structure; rapidly cooling the piezoelectric substrate below the transition temperature at a cooling rate that is sufficiently high for the first crystal structure to persist; and applying an electric field through one or more selected regions of the piezoelectric substrate, such that within the one or more selected regions, a second phase transition occurs and results in a second crystal structure.

A wavelength selective optical switch includes a light input/output unit having a plurality of input/output ports, a polarization plane-independent wavelength dispersion element that splits incident light input from the optical input/output unit into spatially different angles for each wavelength, and synthesizes emergent light from different directions and outputs the light to the optical input/output unit, a condenser element that condenses the light split by the wavelength splitting element, a polarization splitter that splits incident light incident via the condenser element according to a polarization component to result in first and second light beams, aligns a polarization direction by rotating a polarization direction of one of the beams, and synthesizes the incident light by rotating one polarization direction of the emergent light of the same wavelength among the first and second reflected light beams, and a space phase modulation element.

Photonic rotators integrated on a substrate are disclosed for manipulating light polarization.