Abstract: The optical functional element contains aggregates of developed silver grains obtained by developing silver halide grains arranged so as to constitute a periodical structure. The element includes a substrate and a medium layer. The aggregates of the developed silver grains are arranged in the medium layer so as to constitute said periodical structure. The element is produced by first selectively exposing a photo-curing resin layer formed on said substrate in which the silver halide grains are dispersed so as to selectively photo-cure the photo-curing resin layer, then overall exposing the photo-curing resin layer to expose the silver halide grains in the photo-curing resin layer, and thereafter developing the photo-curing resin layer.

Abstract: A rapid mass production of the high performance holographic recording articles including the process and composition are described. To prepare a high performance holographic recording article based on two-component urethane matrix system, for example, polyols and all the additives must be virtually free of moisture contents. Deaeration must be carried out, once isocyanate and polyols including catalysts and all other ingredients are mixed together, to eliminate all entrapped air that is introduced into the mixture during mixing. The deaeration takes time, and the urethane reaction must not be allowed to take place until all air bubbles are evacuated from the isocyanate-polyols mixture. The rapid mass production of this invention overcomes such process limitations and results in a high-volume production of the high performance holographic recording articles.

Abstract: A method of forming an optical device structure having a first region and a second region. The method comprises: providing a polymerizable composite comprising a polymer binder and an uncured monomer, depositing the polymerizable composite on a substrate to form a layer, patterning the layer to define an exposed area and an unexposed area of the layer, irradiating the exposed area of layer, and volatilizing the uncured monomer to form the optical device structure. The step of volatilizing the uncured monomer forms a surface topography and a compositional change between the first region and the second region. The compositional change creates a gradient in refractive index between the first region and the second region.

Abstract: In photomask making, the environmental sensitivity of a chemically amplified photoresist is eliminated, or at least substantially reduced, by overcoating the photoresist with a thin coating (topcoat) of a protective but transmissive material. To provide improved stability during the long time period required for direct writing of a photomask pattern, typically in the range of about 20 hours, the protective topcoat material is pH adjusted to be as neutral in pH as possible, depending on other process variable requirements. For example, a pH adjusted to be in the range from about 5 to about 8 is particularly helpful. Not only is the stability of the chemically amplified photoresist better during direct writing when the protective topcoat is pH adjusted, but a photoresist-coated substrate with pH adjusted topcoat over its surface can be stored longer prior to imaging without adverse consequences.

Abstract: Techniques are disclosed for fabricating a device using a photolithographic process. The method includes providing a first anti-reflective coating over a surface of a substrate. A layer which is transparent to a wavelength of light used during the photolithographic process is provided over the first anti-reflective coating, and a photosensitive material is provided above the transparent layer. The photosensitive material is exposed to a source of radiation including the wavelength of light. Preferably, the first anti-reflective coating extends beneath substantially the entire transparent layer. The complex refractive index of the first anti-reflective coating can be selected to maximize the absorption at the first anti-reflective coating to reduce notching of the photosensitive material.

Abstract: A substrate surface 10 having a photo-sensitive material surface thereon is simultaneously exposed to four plane waves of light at angles of incidence &thgr;, −&thgr;, &phgr; and −&phgr; subtending from the normal of the surface. The four plane waves create an interference pattern on the substrate so as to cause the formation of a periodic structure on the photo-sensitive material surface of the substrate.

Abstract: A fluorinated polymerizable compound useful for fabricating planar optical devices includes at least one fluorinated alkylene or alkylene ether moiety and at least two terminal acrylate moieties, each terminal acrylate moiety being connected to one of the fluorinated alkylene or fluorinated alklene ether moieties by an ester linking group. The fluorinated polymerizable compounds, or macromers, of this invention are useful for forming optical components exhibiting a refractive index comparable to that of glass fiber waveguides, while also exhibiting very low absorption losses. Polymerizable compositions suitable for preparing optical components can be prepared by combining the macromers of the invention with a photoinitiator. Conventional optical monomers may also be employed, if desired.

Abstract: A method of fabricating an optical waveguide structure includes the step of introducing light into a photo-curable liquid resin. The liquid resin can be a mixture of two types of photo-curable liquid resins having different curing initiation wavelengths and different refractive indexes. The method can include dipping one end of a fiber into the liquid mixture. Light having a wavelength &lgr;1 can be radiated from the tip end of the optical fiber in order to cure one of the photo-curable liquid resins thereby forming a waveguide. Light having a different wavelength &lgr;2 can be radiated from an area surrounding the waveguide so as to cure the liquid mixture and form a cladding portion around the waveguide.

Abstract: One principal embodiment of the disclosure pertains to a method of optically fabricating a photomask using a direct write continuous wave laser, comprising a series of steps including: applying an organic antireflection coating over a surface of a photomask which includes a chrome-containing layer; applying a chemically-amplified DUV photoresist over the organic antireflection coating; post apply baking the DUV photoresist over a specific temperature range; exposing a surface of the DUV photoresist to the direct write continuous wave laser; and, post exposure baking the imaged DUV photoresist over a specific temperature range. The direct write continuous wave laser preferably operates at a wavelength of 244 nm or 257 nm. In an alternative embodiment, the organic antireflection coating may be applied over an inorganic antireflection coating which overlies the chrome containing layer.

Abstract: A resist pattern having a good form without any T-top or round top is obtained by coating on a photoresist layer an anti-reflective coating composition containing at least (a) polyacrylic acid, (b) polyvinyl pyrrolidone, (c) CnF2n+1COOOH (wherein n represents an integer of 3 to 11) and (d) tetramethylammonium hydroxide to form an anti-reflective coating, and conducting patternwise exposure and development.

Abstract: Multiple Bragg gratings are fabricated in a single planar lightwave circuit platform. The gratings have nominally identical grating spacing but different center wavelengths, which are produced using controlled photolithographic processes and/or controlled doping to control the effective refractive index of the gratings. The gratings may be spaced closer together than the height of the UV light pattern used to write the gratings.

Abstract: Novel volume holographic elements were made from Bragg diffractive gratings in photo-thermo-refractive (PTR) glass with absolute diffraction efficiency ranging from greater than approximately 50% up to greater than approximately 93% and total losses below 5%. Both transmitting and reflecting volume diffractive elements were done from PTR glasses because of high spatial resolution enabling recording spatial frequencies up to 10000 mm−1. The use of such diffractive elements as angular selector, spatial filter, attenuator, switcher, modulator, beam splitter, beam sampler, beam deflectors controlled by positioning of grating matrix, by a small-angle master deflector or by spectral scanning, selector of particular wavelengths (notch filter, add/drop element, spectral shape former (gain equalizer), spectral sensor (wavelength meter/wavelocker), angular sensor (pointing locker), Bragg spectrometer (spectral analyzer), transversal and longitudinal mode selector in laser resonator were described.

Abstract: A length of oxynitride optical fiber is exposed to actinic radiation that is modulated by an interference technique to form a pattern of refractive index variations that functions as a reflective grating.

Abstract: High-energy pulses of femtosecond lasers form cladding portions of waveguides in bulk glass by producing localized reductions in refractive index. The cladding portions written by the high-energy pulses circumscribe unexposed core portions for defining light-guiding pathways in the bulk glass.

Abstract: Embodiments of the invention provide methods and processes for creating and using high precision molds for creating micro-optical elements, such as micro-lenses. A master mold is created using one of at least gray scale technologies or direct write lithography to provide highly accurate micro-optical contours on a substrate or resist layer upon which the master mold is formed. The master mold may be used to create secondary molds for use in production of highly precise micro-optical elements from various materials.

Abstract: The invention provides organic optical waveguide devices which employ perfluoropolymeric materials having low optical loss and low birefringence. An optical element has a substrate; a patterned, light transmissive perfluoropolymer core composition; and a light reflecting cladding composition on the pattern of the core. Writing of high-efficiency waveguide gratings is also disclosed.

Abstract: A grating fabrication process utilizes real-time measurement of a grating characteristic (such as, for example, grating period chirp, reflectivity, group delay) as a feedback error signal to modify the writing process and improve the characteristics of the finished grating. A test beam is launched through the optical medium during the writing process (or at the end of an initial writing process) and a particular characteristic is measured and used to generate a “corrective” apodization refractive index profile that can be incorporated with the grating to improve its characteristics. The improvements may be applied to a phase (or amplitude) mask used to write the grating (etching, local deformation, coating changes, for example), or the grating itself may be corrected using additional UV exposure, non-uniform annealing, non-uniform heating, and/or non-uniform tension—these techniques applied separately or in an intermittent sequence.

Abstract: The optical functional element contains aggregates of developed silver grains obtained by developing silver halide grains arranged so as to constitute a periodical structure. The element includes a substrate and a medium layer The aggregates of the developed silver grains are arranged in the medium layer so as to constitute said periodical structure. The element is produced by first selectively exposing a photo-curing resin layer formed on said substrate in which the silver halide grains are dispersed so as to selectively photo-cure the photo-curing resin layer, then overall exposing the photo-curing resin layer to expose the silver halide grains in the photo-curing resin layer, and thereafter developing the photo-curing resin layer.

Abstract: A system for fabricating Bragg gratings includes an optical waveguide (e.g., an optical fiber, a planar waveguide), an interference pattern generator (e.g., a transmission phase grating such as a phase mask or a diffraction grating), first motion equipment (e.g. a nanostage), a pulsed light source (e.g. an excimer laser), and second motion equipment (e.g. a stepper motor). A method for fabricating Bragg gratings using this system includes providing relative motion between the optical waveguide and the interference pattern using the nanostage, providing relative motion in discrete increments between the pulsed light source and the assemblage comprising the optical waveguide, nanostage, and interference pattern generator using the stepper motor, and successively exposing the optical waveguide to the pulsed light through the interference pattern generator when the optical waveguide and interference pattern are effectively stationary relative to the pulsed light.

Abstract: A method of forming a hybrid optical component includes the steps of masking and etching a pattern on a core layer of a planar optical component to define at least one alignment element and an optical element and subsequently overcladding the optical element such that a passive platform is formed which exposes a surface of the optical element such as a waveguide and an alignment element for receiving a mirror image alignment element formed on an active platform including an active device, such as a laser. Hybrid components include a passive platform having an alignment element formed therein and a waveguide for receiving an active platform with a mating mirror image alignment element and an active device which aligns with the waveguide when the platforms are mated.

Abstract: In some aspects, the invention relates to methods and systems for creating apodized periodic structures, such as apodized gratings in fibers. To create the periodic structures, a photosensitive medium is exposed to a spatially-varying radiation pattern. During the exposure, the position of the radiation pattern can oscillate with the respect to the photosensitive medium, thereby changing the average local refractive index of the medium. These methods and systems may be used to create regular structures in any appropriate medium, such as doped glasses and photosensitive polymers.

Abstract: The present invention relates to a method of making a diffraction grating device, in which an optical waveguide is irradiated, by way of a phase grating, with light capable of inducing a refractive index modulation in an optical waveguide region of the optical waveguide so as to form a diffraction grating in the optical waveguide region. In the present invention, when modulating the refractive index of the optical waveguide region of an optical fiber, the intensity of refractive index modulation inducing light emitted from a laser light source so as to irradiate the phase grating is adjusted according to individual positions on the phase grating. Alternatively, the scanning speed of a mirror scanned by a stage is adjusted according to the individual positions on the phase grating. Here, the amount of irradiation of refractive index modulation inducing light at each position on the phase grating is adjusted so as to cancel the diffraction efficiency distribution of phase grating.

Abstract: The invention discloses an improvement in the photolithographic patterning method of a photoresist layer formed on a substrate surface with intervention of an anti-reflection coating film, in which the refractive index and the light-absorption coefficient of the anti-reflection coating film are controlled in such a way that, in a graph prepared by plotting the thickness of the anti-reflection coating film taken as the abscissa values and the reflectivity of the light for patterning exposure at the interface between the anti-reflection coating film and the photoresist layer thereon taken as the ordinate values, the range of the variation in the film thickness corresponding to an increment of 0.01 in the reflectivity in the vicinity of the minimum point on the thickness vs. reflectivity curve does not exceed ±0.01 &mgr;m.

Abstract: The invention provides a photoconductive switching element used for light switching of a functional element driven by an AC electric field or AC current which are highly functional and inexpensive and provides a device in which such a photoconductive switching element and a functional element such as a liquid display element are combined and incorporated, and an apparatus, a recording apparatus, and a recording method which are provided with the above-mentioned device. The photoconductive switching element has at least a light transmissible electrode layer, a charge generation layer, a charge transfer layer, and a charge generation layer laminated in this order on a light transmissible substrate. The photoconductive switching element is combined with a functional element to form a device of the present invention, and the device is incorporated in an apparatus or a recording apparatus to fabricate an apparatus or a recording apparatus respectively of the present invention.

Abstract: A method of making a stacked three-dimensional refractive index structure in photosensitive materials using photo-patterning where first determined is the wavelength at which a photosensitive material film exhibits a change in refractive index upon exposure to optical radiation, a portion of the surfaces of the photosensitive material film is optically irradiated, the film is marked to produce a registry mark. Multiple films are produced and aligned using the registry marks to form a stacked three-dimensional refractive index structure.

Abstract: A method that includes exposing a photo-sensitive medium to an optical intensity pattern and then heating the exposed medium. The exposing is performed under conditions that inhibit or prevent the optical intensity pattern from producing refractive index changes in the medium. The heating stimulates a pattern of refractive index changes that is responsive to the optical intensity pattern during the exposing step.

Abstract: A method for writing a Bragg grating in a waveguide comprises the steps of placing the waveguide in a writing position in which the waveguide extends essentially along one axis; generating a beam of ultraviolet radiation; executing a first and a second scan with the said beam along the waveguide through a phase mask, in such a way as to generate interference fringes capable of modifying the refractive index along the said waveguide in a predetermined way; moving the phase mask, during the first or the second scan, with an oscillatory motion about one of its equilibrium positions and along a direction lying at an angle of less than 90° to the axis of the said waveguide, in such a way as to produce, in this scan, an essentially zero envelope of the refractive index; and varying the intensity of the energy of the ultraviolet radiation in a controlled way along the waveguide during the first and the second scan, for example by controlling the scanning velocity.

Abstract: A novel process is proposed for the volume diffractive element (Bragg grating) fabrication in photosensitive silicate glasses doped with silver, cerium, fluorine, and bromine. The process employs a photo-thermo-refractive (PTR) glass of high purity exposed to ultraviolet (UV) radiation of a He—Cd laser at 325 nm followed by thermal development at temperatures from 480° C. to 580° C., preferably at 520° C., from several minutes to several hours. Absolute diffraction efficiency up to 95% was observed for 1 mm thick gratings. Maximum spatial frequency recorded in PTR glass was about of 10,000 mm−1. No decreasing of diffraction efficiency were detected at low spatial frequencies. Original glasses were transparent (absorption coefficient less than 1 cm−1) from 350 to 4100 nm. Induced losses in exposed and developed glass decreased from 0.3 to 0.03 cm−1 between 400 and 700 nm, respectively, and did not exceed 0.01-0.02 cm−1 in the infrared (IR) region from 700 to 2500 nm.

Abstract: The present invention provides a method of inducing a change in refractive index of a photosensitive material. The method comprises the step of simultaneously exposing a region of the material to first and second radiations having first and second wavelengths respectively and being selected, in combination, to induce the change in refractive index in the region, and wherein the first and second wavelengths differ from each other. In one embodiment, the region is a first core (42) of a multiple-core optical fibre (40). The first radiation (48) is propagated along the first core (42) and the second radiation (46) is used to illuminate the first core from outside the fibre (40) through a phase mask (52). This embodiment enables an optical grating to be written in the first core (42) without inducing refractive index changes in the closely-adjacent second core (44).

Abstract: A photoresist layer comprising an optically active component is provided, so that after an incident linearly polarized light penetrates the photoresist layer, the intensity ratio of an S wave polarization and a P wave polarization divided from the linearly polarized light is effectively 1:1 so improving astigmatism.

Abstract: Disclosed is an optical recording medium having a charge generating ability capable of generating electric charges with different polarities upon irradiation with light and a charge transporting ability capable of transporting at least one of the electric charges to separate specially the electric charges from each other forming an electric field upon irradiation with light, the optical characteristics of the optical recording medium being changed depending on the electric field, wherein the charge transporting capability is imparted by a charge transporting material formed of a molecule having a charge transporting capability or a polymer containing a monomer unit having a charge transporting capability. A light intensity pattern is recorded in the optical recording medium depending on the change in the optical characteristics caused by the electric field. The average intermolecular distance of a noticed charge transporting material is defined to fall within a predetermined range.

Abstract: A method of writing a pattern, such as a waveguide, in a bulk glass substrate. The bulk glass substrate can be formed from, for example, borosilicate or sulfide or lead glass. A pulsed laser beam is focused within the substrate while the focus is translated relative to the substrate along a scan path at a scan speed effective to induce an increase in the refractive index of the material along the scan path. Substantially no laser induced physical damage of the material is incurred along the scan path. Various optical devices can be made using this method.

Abstract: Waveguides produced in bulk glass using femtosecond pulsed lasers have diameters and refractive index profiles that are manipulated by additional motions or beams. For example, spot focuses of the femtosecond pulsed lasers trace overlapping or widened tracks by superimposing additional relative motions between the spot focuses and the bulk glass. Additional femtosecond pulsed beams can also be used to produced widened waveguides.

Abstract: A method of creating an undercut sidewall profile within an opening formed in a positive resist layer disposed upon a transparent substrate includes the step of forming a positive resist layer on the upper surface of the substrate, and optically patterning the resist layer by selectively directing light at the resist layer from above the upper surface of the substrate. The lower surface of the substrate is flooded with light to partially expose the lowermost region of the resist layer, and the exposed resist is dissolved to form patterned openings therein. The resulting sidewalls of the patterned resist openings have an enlarged width adjacent the upper surface of the substrate. The sidewalls of the resist layer are then flooded with light from above the substrate, the upper region of the resist layer is cured by an electron beam, and the resist layer is developed a second time to dissolve exposed portions of the resist sidewalls, thereby forming an undercut resist sidewall profile.

Abstract: The present invention is directed to an optical device that includes an optically transparent mask blank that is characterized by a mask blank light transmission variation. An anti-reflective coating is disposed on the optically transparent component resulting in an optical device transmission variation that is less than the mask blank transmission variation. The present invention provides a simple solution to the problem of mitigating Fabry-Perot interference effects in a photomask. Disposing an anti-reflective coating on the light incident side of the photomask substantially reduces multiple reflections of the illuminating UV light. The illumination light propagates through the photomask only once. The AR coating also prevents any cumulative effects due to birefringence, surface roughness, or inhomogeneity.

Abstract: A regenerated optical waveguide is fabricated by hydrogenating an optical waveguide (12) and exposing a grating section (28) to a UV laser beam interference fringe pattern (14) to form a Type I grating. The grating section (28) is exposed for a second period to erase the Type I grating, and then a third period to cause a regenerated optical waveguide grating to form. The resonant wavelength increases during the third period from being substantially the same as the final wavelength of the Type I grating.

Abstract: An optical grating fabrication apparatus having a phase mask for dividing an incident light beam into a plurality of diffracted beams and a focusing arrangement for receiving light from the phase mask and converging at least two non-zero-order diffracted beams together so as to generate an interference region of a characteristic period between the converged beams so that a grating structure can be impressed on an optical waveguide placed in the interference region. Further, a translation stage is arranged to move the phase mask and at least a part of the focusing arrangement with respect to one another under control of a control circuit so as to alter the angle of convergence of the converged beams and thus controllably tune the characteristic period.

Abstract: A radiation sensitive refractive index changing composition comprising (A) a decomposable compound, (B) a non-decomposable compound having a lower refractive index than the decomposable compound (A), (C) a radiation sensitive decomposer and (D) a stabilizer.

Abstract: A fiber type optical component in which nonuniform increase of refractive index is restricted to a minimum in an optical fiber to which light sensitive material is added to the cladding section and the cladding section of the optical fiber, by forming the optical fiber such that the outermost diameter of the light sensitive layer of the optical fiber is twice as large as the mode field diameter or more, or more preferably 2.5 times as large as the mode field diameter, and by forming slant type optical fiber grating by this optical fiber, it is possible to realize the fiber type optical component in which the bandwidth of transmittance loss is narrow and steep in the reflection restricting angle with filtering ability having large transmittance loss.

Abstract: A holographic recording medium comprising an amorphous host material which undergoes a phase change from a first to a second thermodynamic phase in response to a temperature rise about a predetermined transition temperature; a plurality of photo-sensitive molecular units embedded in the host material and which can be orientated in response to illumination from a light source; whereby said molecular units may be so orientated when said host material is at a temperature equal to or above said transition temperature but retain a substantially fixed orientation at temperatures below said transition temperature.

Abstract: A method for manufacturing an optical fiber refractive index grating. The method comprises the steps of, providing a substantially twist-free length of an optical fiber between a first spool and a second spool before attaching the first spool and the second spool to a support having a first surface opposite a second surface. The support and spools provide a filament organizer including the first spool as a lockable spool and the second spool as a rotary spool. The filament organizer further comprises a tensioner coupled to the rotary spool to apply tension to at least a central portion of the length of an optical fiber disposed between the lockable spool and the rotary spool.

Abstract: A method for reducing light reflectance in photolithographic manufacturing process is disclosed including providing an inter-metal dielectric (IMD) layer including at least one via opening extending substantially perpendicular to a thickness therethrough, and, conformally forming an anti-reflectance coating (ARC) layer over said IMD layer such that the ARC layer is formed over sidewalls of the at least one via opening to reduce light reflectance.

Abstract: A rapid mass production of the high performance holographic recording articles including the process and composition are described. To prepare a high performance holographic recording article based on two-component urethane matrix system, for example, polyols and all the additives must be virtually free of moisture contents. Deaeration must be carried out, once isocyanate and polyols including catalysts and all other ingredients are mixed together, to eliminate all entrapped air that is introduced into the mixture during mixing. The deaeration takes time, and the urethane reaction must not be allowed to take place until all air bubbles are evacuated from the isocyanate-polyols mixture. The rapid mass production of this invention overcomes such process limitations and results in a high-volume production of the high performance holographic recording articles.

Abstract: A refractive-index grating fabricated in an optical fiber having a multilayer coating and a method for making refractive-index patterns such as gratings in optical fibers such that the mechanical properties of the original fiber are preserved. The patterns are written into the optical fiber by partially stripping away the outer coating of the fiber, exposing the core of the fiber through the remainder of the coating with an actinic radiation to form the pattern in the photosensitive core of the fiber, followed by recoating the fiber in the stripped area to provide protection of the newly formed pattern from corruption and to preserve the mechanical properties of the fiber.

Abstract: Using polymeric dielectric materials (preferably materials derived from bisbenzocyclobutene monomers) and an electron beam lithography process for patterning this material, we have developed a process for fabricating optical waveguides with complex integrated devices such as gratings. Such gratings are not limited to one-dimensional type gratings but can include 2 dimensional gratings such as curved gratings or photonic crystals. Due to the properties of BCB, this process could also be implemented using optical photolithography depending upon the waveguide dimensions desired and the grating dimensions desired. Alternatively, the optical waveguide could be patterned using optical lithography and the grating can be patterned using electron beam lithography. Gratings with much more dimensional precision can be fabricated using electron beam lithography.

Abstract: A method for manufacturing an optical fiber refractive index grating. The method comprises the steps of, providing a substantially twist-free length of an optical fiber between a first spool and a second spool before attaching the first spool and the second spool to a support having a first surface opposite a second surface. The support and spools provide a filament organizer including the first spool as a lockable spool and the second spool as a rotary spool. The filament organizer further comprises a tensioner coupled to the rotary spool to apply tension to at least a central portion of the length of an optical fiber disposed between the lockable spool and the rotary spool.

Abstract: There are disclosed the following three types of optical recording film: (1) an optical recording film comprising a gel having a network structure of an inorganic substance and a polymer which is from a photopolymerizable compound (A) and present in the network structure in the gel, said gel containing an optical recording-induced difference in the network structure. (2) an optical recording film, which consists essentially of a porous gel having a network structure of an inorganic substance, the porous gel containing recording-induced porosity differences in the network structure. (3) an optical recording film which consists essentially of a porous gel having a network structure of an inorganic substance or a gel obtained by densification of the porous gel, the porous gel or the gel having a recording-induced concavo-convex form on the surface thereof.

Abstract: A system for writing fiber gratings has a plurality of writing stations, each writing station including a fiber mounting fixture for receiving an optical fiber to be exposed to a beam from a laser. The system includes a data capture module for capturing data generated from the exposure of optical fibers in each of the writing stations, and a steering assembly for directing the laser beam to each of the plurality of writing stations in turn.

Abstract: The present invention relates to a method of making a diffraction grating device, in which an optical waveguide is irradiated, by way of a phase grating, with light capable of inducing a refractive index modulation in an optical waveguide region of the optical waveguide so as to form a diffraction grating in the optical waveguide region. In the present invention, when modulating the refractive index of the optical waveguide region of an optical fiber, the intensity of refractive index modulation inducing light emitted from a laser light source so as to irradiate the phase grating is adjusted according to individual positions on the phase grating. Alternatively, the scanning speed of a mirror scanned by a stage is adjusted according to the individual positions on the phase grating. Here, the amount of irradiation of refractive index modulation inducing light at each position on the phase grating is adjusted so as to cancel the diffraction efficiency distribution of phase grating.

Abstract: One principal embodiment of the disclosure pertains to a method of optically fabricating a photomask using a direct write continuous wave laser, comprising a series of steps including: applying an organic antireflection coating over a surface of a photomask which includes a chrome-containing layer; applying a chemically-amplified DUV photoresist over the organic antireflection coating; post apply baking the DUV photoresist over a specific temperature range; exposing a surface of the DUV photoresist to the direct write continuous wave laser; and, post exposure baking the imaged DUV photoresist over a specific temperature range. The direct write continuous wave laser preferably operates at a wavelength of 244 nm or 257 nm. In an alternative embodiment, the organic antireflection coating may be applied over an inorganic antireflection coating which overlies the chrome containing layer.