928 results about "Effective refractive index" patented technology

Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and / or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

Systems and methods for measuring the stress profile of ion-exchanged glass are disclosed, based on the TM and TE guided mode spectra of the optical waveguide formed in the ion-exchanged glass. The method includes digitally defining from the TM and TE guided mode spectra positions of intensity extrema, and calculating respective TM and TE effective refractive indices from these positions. The method also includes calculating TM and TE refractive index profiles nTM(z) and nTE(z) using either an inverse WKB calculation or a fitting process that employs assumed functions for nTM(z) and nTE(z). The method also includes calculating the stress profile S(z)=[nTM(z)−nTE(z)] / SOC, where SOC is a stress optic coefficient for the glass substrate. Systems for performing the method are also disclosed.

The invention relates to a planar ATR and evanescently exited luminescence optical sensor platform, consisting of a transducer and a recognition layer, wherein changes in the effective refractive index of the recognition layer are converted into a measurable variable in accordance with the integrated-optical light pointer principle. The invention relates also to the use of the method and to the method itself using the sensor platform, for example in label-free biosensory analysis.

A multi-core fiber includes an even number of six or more of cores and a clad that surrounds the outer circumferential surfaces of the cores. The cores are formed of two types of cores and in which an effective refractive index difference in a fundamental mode is 0.002 or less in a predetermined range or more that the effective refractive index difference in the fundamental mode is varied according to a core pitch. Two types of the cores are alternately and annularly disposed at regular spacings. A difference in the mode field diameter of light propagating through the cores is 1 μm or less.

Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes are optionally formed from the ligands. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and / or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

In an organic EL element, at the interface between a first electrode and a light-emitting layer, a diffraction grating with grating constants a, b, and c is provided in the form of surface irregularities on the first electrode. The grating constants are determined such that, when the effective refractive index as light experiences in the organic EL element is n, with respect to the periods d01, d10, and d1−1 defining the periodicity of the diffraction grating, n×d01 corresponds to a red region and n×d10 and n×d1−1 correspond to a blue to green region.

In a light waveguide circuit including a plurality of waveguides having different length, a material (10) having a temperature coefficient of a refractive index including a symbol different from that of a temperature coefficient of an effective refractive index of the waveguide (4) is charged into a groove (12) formed by removing the upper clad and the core from the waveguide (4), or a groove (12) formed by removing the upper clad, the core and the lower clad from the waveguide (4). A difference in length of the removed portions between adjacent waveguides is proportional to a difference in length of the waveguides which were not removed and remained.

An optically-active air-clad fiber (30) includes a core (34, 84) that facilitates doping with an ion optically excitable and having a three-level optical transition when pumped at a first end (28) of an optical cavity (46) by a multimode pump source (72) at a pump wavelength (64) for lasing at a signal wavelength (66) different than the pump wavelength (64) at a second end (29) of the optical cavity (46), the core (34, 84) having a refractive index, wherein the core (34, 84) is transformed from the first end to proximate the second end (29) thereof such that the optically-active fiber (30) is multimode at the pump wavelength proximate to the first end (28), and is single-mode at the signal wavelength proximate to the second end (29). An air-clad (36, 86) surrounds at least one portion of the core (34, 84) and has a lower effective refractive index than the refractive index of the core (34, 84).

A bend-loss tolerant multimode fiber transmission system is provided. The system includes: a transmission fiber having a core and a cladding, and a mode-launching system for selectively exciting only a useful portion of the transmission modes, that portion corresponding to high effective refractive indices relative to a refractive index of the cladding the useful portion corresponding to a substantial number of modes. The mode-launching system may include a lead-in fiber, coupled to the transmission fiber, supporting a number of lead-in modes substantially corresponding to the number of transmission modes in the useful portion. The transmission fiber may have a refractive index profile, within a region of its core that is aligned with the lead-in fiber core, which has a shape that matches a refractive index profile shape in the lead-in fiber core. The transmission fiber core may have a graded refractive index profile that is parabolic or nearly parabolic or truncated.

Examples of the present invention include metamaterials, including metamaterial lenses, having material properties that approximate the behavior of a material with low (0<n<1) effective index of refraction. Metamaterials may be designed and tuned using dispersion engineering to create a relatively wide-band low-index region. A low-index metamaterial lens created highly collimated beams in the far-field from a low-directivity antenna feed.

The present invention deals with optical systems for providing short laser pulses. An object of the invention is to provide an optical system providing compact and cost-effective short laser-pulses using fibers with anomalous dispersion and high non-linear thresholds. The object is achieved by a short pulse optical system for generating or processing short laser-pulses, said optical system comprises an optical fiber in the form of a photonic crystal fiber arranged to provide guidance of light in the core region due to the photonic bandgap effect (PBG), where light propagates in a hollow or solid core surrounded by a Silica cladding comprising a substantially periodic distribution of micro-structural elements, and where the refractive index of the core is lower than the effective refractive index of the cladding. The invention may be useful in applications such as laser-based micromachining, thin-film formation, laser cleaning, in medicine and biology.

An optical element includes a base and a large number of structures arranged on the surface of the base, the structures being projections or depressions. The structures are arranged at a pitch shorter than or equal to a wavelength of light in a use environment. An effective refractive index in the depth direction of the structures gradually increases toward the base and has two or more inflection points.

An optical waveguide isolator for use in an optical communication system is disclosed. The optical waveguide isolator comprises a semiconductive light amplifier structure including a semiconductor substrate of first conductivity type having a surface of a layer to be formed thereon, a first cladding layer of first conductivity type formed on the substrate, an active layer formed on the first cladding layer, a second cladding layer of the second conductivity type opposite to first conductivity type, formed on active layer, a first electrode formed on the surface of the semiconductor substrate opposite to the surface to be formed as a layer, and a second electrode formed on the second cladding layer; the first and the second cladding layers and the active layer form an optical waveguide in which the light wave propagates. The semiconductive light amplifier structure further comprises a light absorptive magnetic material layer having light absorption function for the light wave propagating through the optical waveguide. The magnetic material layer is magnetized so as to have the magnetic-field component in the direction which corresponds to the direction where a magnetic vector of the light wave vibrates, the waveguide structure body has a nonreciprocity optical characteristic that effective refractive index changes into the light wave to which the optical waveguide is propagated according to the magnet-optical effect of the light absorptive magnetic material layer according to the direction of propagation, by the effective refractive index change in the nonreciprocity, the attenuation of the first light wave that the optical waveguide is propagated in the first direction caused when the said waveguide is propagated, becomes small more than the attenuation of the second light wave propagated in the second direction opposite to the first direction caused when the said waveguide is propagated.

A periodic electromagnetic medium is disclosed that includes a surface that provides an interface with an ambient medium and a periodic structure that provides negative refraction within the medium of an incident electromagnetic field incident on the surface. In various embodiments the incident electromagnetic field is within a range of frequencies, the medium may include dielectric or metallic material, and has either a positive or negative effective index.

A multimode interference coupler having a tunable power splitting ratio and a method of tuning the splitting ratio. The tuning of the power splitting ratio is achieved by varying an effective refractive index around a portion in a multimode interference section.

A technique is described for generating a cylindrically polarized beam, e.g., a radially or azimuthally polarized beam. An input optical fiber is provided that supports signal propagation in a fundamental LP01 mode. A mode converter device converts the fundamental LP01 mode into a higher-order LP11 mode output that includes a linear combination of modes, including cylindrically polarized TM01 and TE01 modes and mixed HE21 (even) and HE21 (odd) modes. The LP11 mode output propagates through a connected phase-engineered fiber having a refractive index profile that includes a steep refractive index step proximate to a peak amplitude of a mode intensity profile of the LP11 mode, such that at least one cylindrically polarized mode has an effective refractive index that is sufficiently separated from those of the mixed modes to allow for coupling to the at least one cylindrically polarized mode with minimal cross-coupling.

An optical pedestal fiber is configured to be taperable to form a tapered fiber having a mode field diameter at the tapered end that differs from the mode field diameter at the untapered end in correspondence with the difference between the cladding diameter at the tapered end and the cladding diameter at the untapered end. A plurality of such pedestal fibers can be used to construct a tapered fiber bundle coupler that provides matching of both core pitch and mode field diameter between a plurality of input fibers and individual cores of a multicore fiber. Further, the tapered fiber bundle coupler can be constructed using a plurality of fibers, in which individual fibers are configured to have different effective refractive indices, thereby suppressing crosstalk therebetween.

According to the present invention, the method for designing a diffraction grating structure (1), the grating period (d) of the structure comprising at least two grating lines each consisting of a pair of adjacent pillars (2) and grooves (3), comprises the steps of—determining desired diffraction efficiencies ηd of the diffraction orders, and—dimensioning the pillars (2) and grooves (3) so that when calculating for each pillar, on the basis of the effective refractive index neff for the fundamental wave mode propagating along that pillar, the phase shift Φ experienced by light propagated through the grating structure, the differences in the calculated phase shifts between adjacent pillars corresponds to the phase profile Φr required by the desired diffraction efficiencies.

In an electro-optic device, a stack structure including a first silicon layer of a first conductivity type and a second silicon layer of a second conductivity type has a rib waveguide shape so as to form an optical confinement area, and a slab portion of a rib waveguide includes an area to which a metal electrode is connected. The slab portion in the area to which the metal electrode is connected is thicker than a surrounding slab portion. The area to which the metal electrode is connected is set so that a range of a distance from the rib waveguide to the area to which the metal electrode is connected is such that when the distance is changed, an effective refractive index of the rib waveguide in a zeroth-order mode does not change.

Dispersion compensation devices are described which comprise waveguides including sampled Bragg gratings which exhibit comb-like reflectance characteristics. The profile of effective refractive index along the length of the grating is controlled to adjust the position of the teeth and / or to control the dispersion exhibited by the device (i.e. to control the chirp of the grating). The devices can thus be used to provide dispersion compensation to any one of a number of wavelength channels in a WDM system. In preferred arrangements, the effective refractive index distribution is set by a applying a temperature distribution along the length of the grating, or by setting an applied electric field.

The invention relates to a semiconductor optical reflector serving in particular for being disposed facing an integrated laser cavity so as to feed light back into said cavity, and enable it to oscillate continuously. The reflector is made up of a plurality of cascaded Bragg reflector sections. More particularly, said sections are of the same length L and have the same coupling coefficient, and the length L of each pair of sections is given by the following relationship:L= lambda 2 / [(ni+1+ni)x1.7(ni+1 LAMBDA i+1-ni LAMBDA i)]where lambda is the mean value of the Bragg wavelengths reflected by the reflector; ni+1 and ni are the respective effective refractive indices of said adjacent sections; and LAMBDA i+1 and LAMBDA i are the respective periods of said adjacent sections. The reflector of the invention has a wide spectrum band independent of the value of the coupling coefficient.

A binary type diffractive optical element for scalar optics uses a composite artificial material comprising, in a first portion Ma1, microstructures according to a first geometry for which the effective index decreases with the fill factor and, in a second portion Ma2, microstructures according to a second geometry for which the effective index increases with the fill factor. In one example, a composite artificial material is thus formed by hole type microstructures over a first portion, the smallest hole giving the maximum effective index value of said composite artificial material, and pillar type microstructures, the smallest pillar giving the minimum effective index value of said composite artificial material.

An arrangement for achieving and maintaining high efficiency coupling of light between a multi-wavelength optical signal and a relatively thin (e.g., sub-micron) silicon optical waveguide uses a prism coupler in association with an evanescent coupling layer. A grating structure having a period less than the wavelengths of transmission is formed in the coupling region (either formed in the silicon waveguide, evanescent coupling layer, prism coupler, or any combination thereof) so as to increase the effective refractive index “seen” by the multi-wavelength optical signal in the area where the beam exiting / entering the prism coupler intercepts the waveguide surface (referred to as the “prism coupling surface”). The period and / or duty cycle of the grating can be controlled to modify the effective refractive index profile in the direction away from the coupling region so as to reduce the effective refractive index from the relatively high value useful in multi-wavelength coupling to the lower value associated with maintaining confinement of the optical signals within the surface waveguide structure, thus reducing reflections along the transition region.

Disclosed are optical fiber devices incorporating optical fibers with total dispersion greater than material dispersion, and with preferred dispersion values less than +50 ps / nm-km. The desired dispersion values are obtained when light resides substantially in a single higher order mode (HOM) of the fiber, typically the LP02 mode. The optical fibers also preferably have substantial separation between the effective indices of the HOM and any other mode.

The present invention relates to a multi-core fiber having a structure for effectively suppressing crosstalk increase between cores caused by bending within an allowable range. The multi-core fiber comprises a plurality of types of cores respectively extending along an optical axis and a cladding region, and the effective refractive index of each core is set so that, in all pairs of cores of different types, a relative refractive index difference between an effective refractive index of a core of a certain type and an effective refractive index of a core of another type satisfies a condition regulated according to a core spacing between cores and a bending radius.

The invention discloses a graphene phase type light modulator based on a planar waveguide. The light modulator comprises a substrate layer, the light waveguide, a first dielectric filling layer, a second dielectric filling layer and an electrode structure. The first dielectric filling layer, the second dielectric filling layer and the light waveguide are located at the upper end of the substrate layer. The light waveguide is composed of a first rectangular waveguide body, a first isolation dielectric layer, a first graphene layer, a second isolation dielectric layer, a second graphene layer, a third isolation dielectric layer and a second rectangular waveguide body in sequence from bottom to top. The electrode structure comprises a first metal layer and a second metal layer, and the first metal layer and the second metal layer are deposited on the upper end face of the extending part of the first graphene layer and the upper end face of the extending part of the second graphene layer respectively. The graphene layers are embedded in the light waveguide bodies, interaction between graphene and light is enhanced, the resistance of a system is reduced, the modulation rate of the modulator is increased, the effective refractive index change in the waveguide can be effectively regulated, and dynamic modulation on a light field phase is achieved.