Provided are a monitoring device, a monitoring method, an optical amplifier, and an optical transmission system that are adapted for an increase in the number of cores in a multi-core optical fiber transmission path, and that are suitable for crosstalk monitoring. The monitoring device monitors a multi-core optical fiber transmission path comprising a plurality of use core and at least one or more non-use cores. The monitoring device comprises: an applying means for applying dithering to signal light propagating in the use cores; a monitoring means for monitoring the power of the non-use cores; and a separating means for separating a monitoring result from the monitoring means into power components from the plurality of use cores.

A multicore optical fiber comprises a common cladding and a plurality of core portions disposed in the common cladding. Each of the core portions includes a central axis, a core region extending from the central axis to a radius r.sub.1, the core region comprising a relative refractive index Δ.sub.1, an inner cladding region extending from the radius r.sub.1 to a radius r.sub.2, the inner cladding region comprising a relative refractive index Δ.sub.2, and a depressed cladding extending from the radius r.sub.2 to a radius r.sub.3, the depressed cladding region comprising a relative refractive index Δ.sub.3 and a minimum relative refractive index Δ.sub.3 min. The relative refractive indexes may satisfy Δ.sub.1>Δ.sub.2>Δ.sub.3 min. The mode field diameter of each core portion may greater than or equal to 8.2 μm and less than or equal to 9.5 μm.

An integrated optical system includes a wavelength tunable optical source and a photonic integrated circuit (PIC). The PIC includes a set of spatial waveguide switches having an input optically coupled to the wavelength tunable optical source and a plurality of outputs. The PIC also includes an optical emitter having a plurality of inputs, each being coupled to a respective one of the plurality of outputs of the set of spatial waveguide switches, the optical emitter configured to produce at an output an optical beam having a wavelength dependent emission direction that changes as light is switched by the set of spatial waveguide switches such that the optical beam may be steered in two dimensions.

A detection system for an alignment sensor, and an alignment sensor and lithographic projection apparatus comprising such a detection system is disclosed. The detection system comprises at least one detection circuit; and a plurality of optical fiber cores for transporting a measurement signal to the at least one detection circuit. At least as subset of the plurality of optical fiber cores are selectively switchable between a detection state and a non-detection state, thereby defining a configurable detection spot.

A method of manufacturing a multicore fiber includes: an initial-preform forming process of forming an initial preform by arranging in an array a plurality of core rods each including a core portion and a cladding portion formed around outer periphery of the core portion; and an optical fiber manufacturing process of manufacturing an optical fiber from the initial preform. Further, the core rods include a plurality of holes, and the core rods are arranged in a manner that one hole is arranged between two core portion adjacent to each other in the initial-preform forming process.

Multicore optical fibers with low bend loss, low cross-talk, and large mode field diameters In some embodiments a circular multicore optical fiber includes a glass matrix; at least 3 cores arranged within the glass matrix, wherein any two cores have a core center to core center spacing of less than 29 microns; and a plurality of trench layers positioned between a corresponding core and the glass matrix, each trench layer having an outer radius of less than or equal to 14 microns and a trench volume of greater than 50% Δ micron.sup.2; wherein the optical fiber has a mode field diameter of greater than about 8.2 microns at 1310 nm, and wherein the optical fiber has an outer diameter of less than about 130 microns.

In some implementations, a waveguide may comprise an inner core to receive a first beam and an outer core surrounding the inner core to receive a second beam that is displaced from the first beam by an offset. The outer core may comprise a beam guiding region that rotationally expands over a length of the waveguide into an annulus that concentrically surrounds the inner core or a partial annulus that partially surrounds the inner core. For example, the beam guiding region may be defined by one or more low refractive index features that have a varied orientation and/or a varied shape over the length of the waveguide such that the second beam enters the waveguide as an offset beam and exits from the waveguide as a ring-shaped beam or a partial ring-shaped beam.

According to one aspect, the invention concerns a device for transporting and controlling light pulses for lensless endo-microscopic imaging and comprises: a bundle of N monomode optical fibers (F.sub.1) arranged in a given pattern, each monomode optical fiber being characterized by a relative group delay value (Ax) defined relative to the travel time of a pulse propagating in a reference monomode optical fiber (F.sub.0) of the bundle of fibers (40), an optical device for controlling group velocity (50) comprising a given number M of waveplates (P.sub.j) characterized by a given delay (8t.sub.j); a first spatial light modulator (51) suitable for forming from an incident light beam a number N of elementary light beams (B.sub.i) each of which is intended to enter into one of said optical fibers, each elementary beam being intended to pass into a given waveplate such that the sum of the delay introduced by said waveplate and the relative group delay of the optical fiber intended to receive said elementary light beam is minimal in absolute value; a second spatial light modulator (52) suitable for deviating each of the N elementary light beams such that each elementary light beam penetrates into the corresponding optical fiber perpendicularly to the entrance face of the optical fiber.

A waveguide is provided for transmitting electromagnetic waves, in particular for transmitting image information, from a proximal end to a distal end, along a transport direction running between the ends and a via a cross-section running transversely to the transport direction. The waveguide has a plurality of structural elements, wherein at least two different types of structural elements have a first type with a first refractive index and a second type with a second refractive index. Each of the structural dements extends along the transport direction and over a part of the cross-section of the waveguide such that a plurality of cross-sectional regions are defined in the cross-section of the waveguide, each cross-sectional region corresponding to the cross-section of an individual structural element.

An optical amplifying fiber includes: at least one single core portion doped with a rare-earth element; an inner cladding portion configured to enclose the at least one core portion, the inner cladding portion having a lower refractive index than maximum refractive index of each core portion; and an outer cladding portion configured to enclose the inner cladding portion, the outer cladding portion having a lower refractive index than refractive index of the inner cladding portion, wherein the inner cladding portion includes a plurality of air bubbles.