An optical fiber bending loss measuring method for obtaining a bending loss of an optical fiber by applying bending to the optical fiber with mandrels provided between a feeding portion and a fixing portion and arranged alternately in a longitudinal direction of the optical fiber. The method includes fixing the optical fiber to the fixing portion by passing the optical fiber fed out from the feeding portion between the mandrels, moving the movable mandrel to a forward position and applying bending to the optical fiber by holding the optical fiber between the adjacent mandrels, and obtaining the bending loss of the optical fiber while the bending is applied to the optical fiber.

A mode control system and method for controlling an output mode of a broadband radiation source including a photonic crystal fiber (PCF). The mode control system includes at least one detection unit configured to measure one or more parameters of radiation emitted from the broadband radiation source to generate measurement data, and a processing unit configured to evaluate mode purity of the radiation emitted from the broadband radiation source, from the measurement data. Based on the evaluation, the mode control system is configured to generate a control signal for optimization of one or more pump coupling conditions of the broadband radiation source. The one or more pump coupling conditions relate to the coupling of a pump laser beam with respect to a fiber core of the photonic crystal fiber.

A mode-dependent loss measurement device measures a mode-dependent loss of a measurement target optical fiber including a coupled MCF. The device includes a light source, a light receiver, a mode coupled state changer, and an analysis unit. The light source inputs light to an input end of an excitation optical fiber including another coupled MCF. The light receiver detects a sum of powers of outputted light beams from a plurality of core end faces positioned on an output end of the measurement target optical fiber. The mode coupled state changer changes a mode coupled state of the excitation optical fiber. The analysis unit obtains a mode-dependent loss of the measurement target optical fiber from variations in optical powers detected by the light receiver.

An optical device with an optical transmitter circuit and an optical receiver circuit integrated on a substrate has at least one of a first oblique waveguide extending obliquely with respect to an edge of the substrate at or near an incident port for introducing a light emitted from a light source to the optical device, a second oblique waveguide extending obliquely with respect to the edge of the substrate at or near a signal receiving port optically connected to the optical receiver circuit, and a third oblique waveguide extending obliquely with respect to the edge of the substrate at or near a signal transmission port optically connected to the optical transmitter circuit.

A loop back connector and methods for testing lines in a fiber optic network are disclosed. The loop back connector includes a ferrule having an interface side constructed for optical connection to a multifiber optical cable. The loop back connector also includes first and second optical loop back paths, each having first and second terminal ends positioned at the interface side. The terminal ends of each loop back path are adapted to be aligned to fibers in the multifiber optical cable. The method includes injecting a signal on a first optical path at a first location, looping back the signal at a second location onto a second optical path, and receiving the signal on the second optical path at the first location.

An embodiment optical test circuit includes a first optical circuit and a second optical circuit formed on a substrate, an input optical waveguide optically connected to the first optical circuit and the second optical circuit, and an output optical waveguide optically connected to the first optical circuit and the second optical circuit. The optical test circuit also includes a light emitting diode optically connected to the input optical waveguide, and a photodiode optically connected to the output optical waveguide.

Aspects of the present disclosure describe a method for estimating mode field distribution in optical fibers from guided acoustic-wave Brillouin scattering wherein light for which the optical mode-field distribution is determined remains in the optical fibers and the distribution is made for light inside the fiber, and not at a fiber/air interface or other perturbation points to the fiber resulting in a more accurate representation of the optical mode-field distribution in the fiber. Since light is always in the fiber during the determination, no complicated fiber preparation steps or procedures are required and the mode-field distribution is determined as an average distribution along the length of the fiber under test.

A probe device includes an optical fiber array including an optical fiber to be in optical communication with an optical integrated circuit board, the optical integrated circuit board including an optical coupling element and a reflection mirror, a base substrate fixing the optical fiber, and an intermediate substrate including a hole into which the optical fiber is inserted, and a probe mirror to reflect an optical signal between the reflection mirror and the optical coupling element.

The purpose of the present disclosure is to provide a mode field diameter test method and test device that enable acquisition of a mode field diameter for an arbitrary higher-order mode. The present disclosure is a mode field diameter test method including: a test light incidence procedure for selectively causing test light to be incident in a mode subject to measurement, on one end of an optical fiber 10 under test; a far-field pattern measurement procedure for measuring a far-field pattern of the mode subject to measurement, with respect to a divergence angle θ at the other end of the optical fiber under test, by a far-field scanning technique; and a mode field diameter calculation procedure for calculating, using an equation, a mode field diameter from information about incident mode orders in the test light incidence procedure and the far-field pattern measured in the far-field pattern measurement procedure.

An integrated circuit comprises: at least one photonic layer that includes one or more optical waveguides; a first optical coupler that couples at least a first optical mode outside of the photonic layer to a first waveguide in the photonic layer; a photonic device that includes one or more ports in the photonic layer; a first multi-port optical coupler that includes three or more ports in the photonic layer, including a first port optically coupled to the first optical coupler, a second port optically coupled to a first port of the photonic device, and a third port optically coupled to a first optical reflector configured to send substantially all optical power emitted from the third port of the first multi-port optical coupler back to the third port of the first multi-port optical coupler.