Abstract: An arrayed waveguide grating 101 is shown, which comprises at least one input waveguide 103, a plurality of output waveguides 104, at least one wavelength compensation output waveguide 105 disposed adjacent to the output waveguide 104, a channel waveguide array 107, an input side slab-waveguide 108, and an output side slab-waveguide 109. The wavelength compensation output waveguide 105 has a tapering connecting portion connected to the output side slab-waveguide 105. Thus, the outputted light has a sharp spectrum, thus permitting ready wavelength compensation.

Abstract: A multi-wavelength cascaded Raman resonator (“MWCRR”). The MWCRR has an optical source for pumping optical radiation centered around an input wavelength. The MWCRR further includes a Raman fiber having at least a first set of optical gratings for converting the pumped optical radiation to wavelengths other than the input wavelength. The Raman fiber also has at least one adjustable output coupler having a variable reflectivity for controlling the power of the optical radiation propagating from the at least one set of optical gratings at the wavelengths other than the input wavelength.

Abstract: There is disclosed a method for the holographic recording of data, wherein a hologram containing the date is recorded in a waveguide layer (3). The holograms are formed in a layer structure containing multiple waveguide layers (3). Coupling means (12) are provided for selectively coupling the reference beam (11) into the single waveguide layers (3) of the layer structure. The invention also relates to an arrangement for holographic recording of data, comprising a data storage medium with a waveguide holographic storage layer, and an optical system for writing and reading the holograms. The optical system comprises means for imaging an object beam (5) and a reference beam (11) on the storage medium. The arrangement comprises multiple waveguide holographic storage layers (3) in the storage medium, and means for selectively coupling the reference beam (11) into the single waveguide layers (3) of the layer structure.

Abstract: An optical modulation apparatus includes an optical signal input section, an optical signal propagation path, an optical modulator that modulates the phase of optical signals in at least two of a plurality of optical paths, and a wavelength selective filter that selectively reflects and transmits. Optical signals input via the input section are divided into a plurality of optical paths at a branching point and phase modulated by the phase modulator, that divides the optical path into a plurality of optical paths. Light transmitted by the filter is output via the output section, while light reflected by the filter travels back along the optical path and is again phase modulated by the phase modulator combined at the branching point and output from the input section as an intensity modulated optical signal.

Abstract: Output power fluctuations in a distributed feedback laser arrangement are reduced by inducing a saturable absorption grating in a saturable absorption region. Light is coupled into a DFB region and amplified in an amplification region. A feedback loop reflects a portion of the amplified light, and the counter-propagating beams induce an absorption grating in a saturable absorption region which suppresses output oscillations. The amplification region can comprise an erbium doped fiber, and the saturable absorption region can comprise an underpumped portion of such a fiber, or a further length of such fiber, or a planar waveguide.

Abstract: An optical transmit module. In one aspect of the present invention, an optical beam is generated with a gain medium disposed in a semiconductor substrate. A tunable Bragg grating also disposed in the semiconductor substrate may be optically coupled to the gain medium to tune an output wavelength of the optical beam. The semiconductor substrate further includes an optical modulator optically coupled to receive the optical beam. The optical modulator is coupled to modulate the optical beam in response to a modulation signal.

Abstract: A dispersion compensating fiber 1 is placed in the form of a coil or bundle within a housing 2, and a filling material 3 having a viscosity of 0.01 Pa·s to 0.6 Pa·s at normal temperature before curing is filled in a space around the dispersion compensating fiber 1 within the housing 2 and then the filling material is cured. As a result, a change of transmission loss caused by a temperature variation due to heat cycles of the dispersion compensator can be reduced. A difference in transmission loss can be further reduced by employing a method of placing the dispersion compensating fiber in the housing in the form of a loosely wound bundle and then pouring the filling material, or a method of applying vibration to the housing, in which the dispersion compensating fiber is placed, when pouring the filling material.

Abstract: An optical filter comprising a first CBG including a first end and a second end, a second CBG of the same structure as the first CBG, including a third end of the same structure as the first end and a fourth end of the same structure as the second end, and a circuit including an input port and an output port. The circuit receives a first optical signal via the input port and brings it to the first end of the first CBG, the circuit receives a second optical signal produced by reflecting the first optical signal from the first CBG and brings the second optical signal to the fourth end of the second CBG, and the circuit receives a third optical signal produced by reflecting the second optical signal from the second CBG and outputs the third optical signal via the output port.

Abstract: A wavelength division multiplexing (WDM) switching includes one or more optical add/drop multiplexers (OADMs) to drop or add optical signals on one or more optical channels. The OADM may be a 1-channel OADM which includes first and second conductors arranged periodically so as to have a pair of different polarities, an optical waveguide type coupler dropping or adding an optical signal of a specific channel by an electric field generated from the first and second conductors, a power supply unit supplying the second conductor with a power, and a switch placed between the second conductor and power supply unit to control a power supply of the second conductor, so as to control generation and termination of the electric field in accordance with an operation control signal.

Abstract: An optical dispersion compensation device includes a first optical compensation unit that applies non-linear dispersion compensation across a signal band, the first optical compensation unit being coupled to a second optical compensation unit that applies a degree of linear dispersion compensation across the signal band. The approach taken is to provide broadband dispersion compensation by applying dispersion slope compensation across the signal band to equalise residual dispersion slope and by applying a degree of linear compensation separately to affect the required linear dispersion compensation. Using these two degrees of freedom it is possible to set the desired dispersion slope and linear dispersion (whether positive or negative) to affect broadband dispersion compensation without needing to demultiplex the optical signal.

Abstract: In a grating-assisted coupler, the mode of the first waveguide of the coupler may include some electric field in the second waveguide, with the effect that when light lasses from an input waveguide to the first waveguide, some light is launched, or injected, directly into the mode of the second waveguide. This injected light may or may not be in phase with the light subsequently coupled into the side of the second waveguide from the first waveguide via grating assistance. The grating structure is formed to ensure a desired phase relationship between the injected light and the grating coupled light: under certain conditions of relative phase, the transmission through the coupler may be increased and the bandwidth may be reduced.

Abstract: The present invention proposes optical fiber equipment having a Bragg grating tunable by a piezoelectric actuator, the equipment comprising an optical fiber, a Bragg grating photoinduced in said fiber, a support for supporting said fiber and comprising two uprights at opposite ends of said Bragg grating, each upright having a first holding element for holding said fiber, and a piezoelectric actuator held via its ends between the two uprights, said actuator being longitudinally prestressed in compression between said uprights.

Abstract: An arrayed waveguide grating deposited on a wafer that includes an upper semiconductor layer comprising a first port, a plurality of second ports, a gate oxide layer, a polysilicon layer, and a plurality of arrayed waveguides. The gate oxide layer is deposited above the upper semiconductor layer. The polysilicon layer is deposited above the gate oxide layer. The plurality of arrayed waveguides extend between the first port and each one of the plurality of second ports. Each one of the plurality of arrayed waveguides are at least partially formed by the upper semiconductor layer, the polysilicon layer, and the gate oxide layer. Each one of the arrayed waveguides is associated with a portion of the polysilicon layer. Each portion of the polysilicon layer has a different cross-sectional area, wherein each of the arrayed waveguides has a different effective mode index.

Abstract: The present invention relates to a Bragg grating filter optical waveguide device, comprising an optical fiber provided with a Bragg grating region which is externally strained to alter the range of chirping. The external strain is induced by a gradient-generating mechanical body bonded onto the length of the fiber grating.

Abstract: A tunable dispersion compensation device comprises an optical waveguide having a grating, a plurality of heaters arranged along an optical axis of the optical waveguide, and a pulsed-current supplying unit for producing a desired temperature distribution in the grating by supplying a plurality of pulsed currents to the plurality of heaters, respectively. The grating can be a chirped grating. The pulsed-current supplying unit can include a pulse width control unit for adjusting the pulse widths of the plurality of pulsed currents supplied to the plurality of heaters, respectively, according to the desired temperature distribution to be produced in the grating. Preferably, the pulsed-current supplying unit supplies the plurality of pulsed currents to the plurality of heaters at different times, respectively.

Abstract: A (de)multiplexer for use in optical communications systems for multiplexing and demultiplexing an optical signal consisting of optical channel(s) of different wavelength(s) includes a multiplex optical waveguide propagating a plurality of optical channels and a plurality of single channel optical waveguides, each propagating a single channel. Each of the waveguides has a receiving/transmitting end. A diffraction grating is optically coupled between the multiplex optical waveguide and the single channel optical waveguides for diffracting an optical signal between the receiving/transmitting end of the multiplex optical waveguide and the receiving/transmitting end of the single channel optical waveguide.

Abstract: A core 2 is co-doped with Ge in a general concentration equivalent to that in a core of an optical fiber to be connected as well as Sn and Al in predetermined concentrations. A glass part F including the core and a cladding 3 is coated with a primary coat layer 4 of a UV transmitting resin which transmits UV of 240 nm through 270 nm but cures by absorbing UV of a shorter wavelength band than 240 nm or a longer wavelength band than 270 nm. A grating is written in the core by irradiating the core with UV through the primary coat layer. The primary coat layer is covered with a secondary coat layer 7 of a resin having a negative coefficient of linear expansion so as to cancel and suppress expansion/shrinkage of the glass part in accordance with temperature change derived from the positive coefficient of linear expansion.

Abstract: A phase mask, for writing fiber Bragg gratings (FBG) in an optical fiber, adjusts the amplitude and the phase of the FBG, while maintaining a constant mean index of refraction of the fiber in a single pass. Specifically, the phase mask embodies the amplitude information so that the amplitude information is an integral part of the phase mask and preferably cannot be separated from the phase information. A first embodiment employs a reflective or opaque surface, defining a window, on the substrate of a phase mask controlling the amplitude of light passing through the phase mask. Another embodiment employs a polygonal shaped grating region on a clear substrate. A third embodiment interleaves regions of grating and smooth substrate surface. Preferred embodiments employ two areas of gratings with the areas disposed: perpendicularly, out of bandwidth or out of phase, relative to each other or additive.

Abstract: Photosensitive optical materials are used for establishing more versatile approaches for optical device formation. In some embodiments, unpatterned light is used to shift the index-of-refraction of planar optical structures to shift the index-of-refraction of the photosensitive material to a desired value. This approach can be effective to produce cladding material with a selected index-of-refraction. In additional embodiments gradients in index-of-refraction are formed using, photosensitive materials. In further embodiments, the photosensitive materials are patterned within the planar optical structure. Irradiation of the photosensitive material can selectively shift the index-of-refraction of the patterned photosensitive material. By patterning the light used to irradiate the patterned photosensitive material, different optical devices can be selectively activated within the optical structure.

Abstract: A Tapped Optical-Fibers Processor (TOP) for correlation and autocorrelation facilitates the processing if radar and SAR (synthetic aperture radar) signals, allowing fine resolution to be obtained without fast front-end sampling while significantly reducing digital computational burdens. Particularly in conjunction with radar signal processing, the input signal may be composed of the sum of at least two or more signals, in which case the output may include the autocorrelations of both inputs as well as the generation of a cross-correlation of the two autocorrelations.

Abstract: A wavelength tunable filter for optical communication systems has an optical fiber containing a Bragg grating disposed within a compliant support block. A length of the fiber is wrapped in a spiral of fixed pitch around the longitudinal axis of a cylindrical polymer support block. The support block is placed within a support frame to which a micrometer screw assembly is attached and oriented to apply a variable mechanical load substantially parallel to the longitudinal axis of the cylindrical support block. Application of the load introduces a strain on the support block, changing the period of the refractive index in the fiber Bragg grating with a resulting shift in the Bragg reflection peak.

Abstract: A hitless wavelength selective optical device includes a first thermo-optic switch (TOS), a second TOS, a first waveguide, a second waveguide, a third waveguide, a heating element and a control unit. The first TOS includes receives a wavelength division multiplexed (WDM) signal at a first port of the first TOS. The second TOS provides at least one channel of the WDM signal at a first port of the second TOS. The first waveguide is coupled between second ports of the first and second TOS. The second waveguide includes a tunable filter that reflects a selected channel from the received WDM signal and coupled between the third ports of the first and second TOS.

Abstract: A partially configurable optical add/drop multiplexer (OADM) is provided. Fixed single channel and wideband tunable fiber Bragg gratings may be used in combination. OADM channel configuration may be changed by tuning one or more tunable fiber Bragg gratings.

Abstract: A fiber Bragg grating (1) includes an optical fiber (2) having an optical fiber core (20) made of a material whose index of refraction varies with temperature, a thermal electric cooler (3) mounted on the optical fiber for maintaining “cold spots”, and a resistor (4) including a plurality of micro heating elements (40) arranged on the optical fiber for forming periodic “hot spots”. A temperature of the “hot spots” varies with a current flowing through the resistor, thereby controlling an index of refraction of narrow cross sections of the optical fiber core. Therefore, a state of reflection of the fiber Bragg grating can be tuned over a continuous range.

Abstract: A chiral in-fiber tunable polarizer implemented in a chiral fiber structure is provided. The chiral fiber is selected with a predetermined handedness and scatters (by reflecting, coupling into the fiber core or otherwise) the circularly polarized light matching its handedness while transmitting circularly polarized light of opposite handedness. By combining the chiral fiber with another fiber component having a non-cylindrical core, the inventive apparatus produces a linearly polarized wave with a predetermined orientation. The orientation may be adjusted by rotating the fiber component around its central axis. The chiral fiber structure may be configured as a long period chiral fiber grating. Optionally, the chiral fiber structure may be configured with a variable pitch along its length, such as a chirped fiber grating, an apodized fiber grating, or a set of multiple sequential chiral polarizer elements with different pitches.

Abstract: A novel multimode fiber structure with modal propagation characteristics tailored to facilitate the creation of narrowband, high reflectivity, fiber Bragg gratings is disclosed. The fiber structure comprises concentric cylindrical shells of higher and lower refractive index material. A full vector, second order finite element method is used to analyze the proposed multimode fiber structure. Simulations of the modal profiles show that high order modes are localized to particular high refractive index shells. We present the theoretical characterization of the modal propagation constant as a function of inner shell radius, shell separation, and harmonic mode parameter. It is shown that a fiber with a minimum inner shell radius of at least 25&lgr; (where &lgr; is the vacuum wavelength), and a minimum shell separation of at least 10&lgr; provides a reasonable trade off between fiber size and grating performance.

Abstract: There is provided an apparatus for fabricating an apodized fiber grating.

Abstract: A tunable demultiplexer accepts an input optical signal that has multiple spectral bands and provides multiple output signals. Each of the output signals corresponds to a selected one of the spectral bands. The tunable demultiplexer has at least one wavelength routing element and at least one optical arrangement disposed to exchange light with the wavelength routing element. The wavelength routing element is of the type adapted for selectively routing wavelength components of a first optical signal onto multiple second optical signals according to a configurable state.

Abstract: To produce a fiber laser (106) a double-cladding active fiber (114) doped with Yb is predisposed to receive, near a first end (114a), a UV radiation suitable to write a first Bragg grating; during the writing process, a scanned pumping radiation is fed to the first end of the active fiber in order to excite an amplified stimulated emission between the first grating and the reflecting surface of a second end (114b) of the active fiber, previously cut and cleaned, and to consequently induce a laser emission from the active fiber; the optical power of the laser emission is measured and processed to obtain the laser efficiency; when a maximum value of the efficiency is reached, the writing process is stopped; similar steps are used to write a second grating near the second end (114b) of the active fiber.

Abstract: The invention proposes to increase the signal/noise ratio in a long-haul transmission system by: filtering noise (1) outside the range of wavelength of the signals transmitted, shifting (2) the wavelength of the signals transmitted, and filtering the signals transmitted (5) that have undergone wavelength shifting. The wavelength of the signals can be shifted by widening the spectrum of the signals or by optical phase conjugation.

Abstract: A polarization-independent optical switch is disclosed for switching at least one incoming beam from at least one input source to at least one output drain.

Abstract: Fibre optic apparatus for accurate and repeatable measurements of light comprising one or more wavelength ranges, and system employing the apparatus. The apparatus according to the invention comprises: a directional coupler adapted to lead the light into an optical fibre, said optical fibre containing at least one analysis filter for each wavelength range, said analysis filters consisting of at least one fibre-optical Bragg-grating (FBG) which reflects incident light with a chosen wavelength back through said directional coupler and onto a detector having an associated signal processing unit, a modulator device for pulsing the incident light with a chosen pulse width, and an optical fibre delay line in front of each analysis filter, with a length adapted to provide for a sufficient time delay larger than the pulse width, so that the pulses reflected from each analysis filter at different wavelengths can be separated in time and thereby be demodulated in the signal processing unit.

Abstract: A dynamic gain flattening filter is provided that offers a smooth spectral response. The filter includes an input/output port for launching a beam of light, a dispersive element for dispersing the beam of light into a plurality of monochromatic sub-beams of light, and discrete array of controllable elements for receiving the plurality of sub-beams of light. The filter is designed such that each sub-beam of light is incident on more than one element of the discrete array for selective attenuation before being recombined by the dispersive element and redirected back to the input/output port. In another embodiment, a beam-folding mirror is provided to direct the attenuated beam to a separate output port.

Abstract: An optical element is provided with one or more sets of diffractive elements. Individual diffractive element transfer functions collectively yield corresponding overall transfer functions between corresponding entrance and exit ports. Diffractive elements are defined by contours that include diffracting region(s) altered to diffract, reflect, and/or scatter incident optical fields (altered index, surface, etc). Element transfer functions are determined by: fraction of contour filled by diffracting region(s) (partial-fill grayscale); and/or the spatial profile of the diffracting region(s) (profile-based grayscale). Optical elements may be configured: as planar or channel waveguides, with curvilinear diffracting segments; to support three-dimensional propagation with surface areal diffracting segments; as a diffraction grating, with grating groove segments.

Abstract: An adaptive dispersion compensation device offered performs stably the dispersion compensation, inclusive of waveform shaping, for an optical fiber transmission line. The device comprises a plurality of basic units each including a chirp-bragg fiber grating which is formed in an optical waveguide, a reflection mirror which is disposed on the light input side of the chirp-bragg fiber grating by being detachable and an optical circulator which is connected to the reflection mirror, means of connecting the basic units in series, and means of controlling the dispersion characteristics of each chirp-bragg fiber grating by applying a temperature gradient to it along its axis. The individual chirp-bragg fiber gratings with the application of temperature gradients vary the dispersion quality of the lights passing through the basic units, thereby controlling the dispersion quality of the input signal light stably and releasing the compensated signal light.

Abstract: An optical filter comprising a first CBG including a first end and a second end, a second CBG of the same structure as the first CBG, including a third end of the same structure as the first end and a fourth end of the same structure as the second end, and a circuit including an input port and an output port. The circuit receives a first optical signal via the input port and brings it to the first end of the first CBG, the circuit receives a second optical signal produced by reflecting the first optical signal from the first CBG and brings the second optical signal to the fourth end of the second CBG, and the circuit receives a third optical signal produced by reflecting the second optical signal from the second CBG and outputs the third optical signal via the output port.

Abstract: The present invention provides a family of novel polymeric devices including an optical laser and optical amplifier, as well as novel methods and materials for their manufacture. The devices of the invention preferably each comprise optical nonlinear second-order polymers (including polymer blends) which exhibit electroluminescence. The devices can be present in a single layer (e.g., either singly, or in an array including a side-by-side arrangement), and optionally comprise a plurality of layers, such as at least two layers, preferably which are stacked (e.g., either a stack of single devices, or a stack of arrayed devices). The devices of the invention optionally can be fabricated attached to other devices (optical or non-optical) or elements of devices (e.g., electrodes and the like).

Abstract: An integrated multifunctional apparatus for fiber optic communication systems includes: at least one input fiber; a lens optically coupled to the at least one input fiber; a diffraction grating optically coupled to the lens at a side opposite to the at least one input fiber; at least one output fiber optically coupled to the lens at the side opposite to the diffraction grating; and a plurality of movable rods residing at the side of the lens opposite to the diffraction grating, where the plurality of movable rods is capable of intercepting a variable portion of a light traversing through the lens. The apparatus is capable of simultaneously performing the functions of multiplexing or de-multiplexing, variable optical attenuation and/or optical detection of plural channels comprising a wavelength division multiplexed composite optical signal.

Abstract: A fiber Bragg grating (1) includes an optical fiber (2) having an optical fiber core (20) made of a material whose index of refraction varies with temperature, a thermal electric cooler (3) mounted on the optical fiber for maintaining “cold spots”, and a resistor (4) including a plurality of micro heating elements (40) arranged on the optical fiber for forming periodic “hot spots”. A temperature of the “hot spots” varies with a current flowing through the resistor, thereby controlling an index of refraction of narrow cross sections of the optical fiber core. Therefore, a state of reflection of the fiber Bragg grating can be tuned over a continuous range.

Abstract: Method and apparatus for polarizing light propagating in an optical fiber. The apparatus has an optical fiber having a Fiber Bragg Grating (FBG) section of predetermined length therein, and a force applying device for applying a lateral force to a predetermined portion of the FBG section. The predetermined portion comprises a predetermined percentage of the predetermined length. When the predetermined percentage is equal to or greater than about 10 percent, two polarization states for the light passing through the optical fiber are obtained. When the predetermined percentage is a small portion of the grating length, for example, about 1 percent of the length of a chirped grating, a finely tunable optical fiber polarizer is provided. The apparatus can use standard optical fiber such as telecomm fiber and provides various advantages including the capability of being switched on and off by simply applying and withdrawing the lateral force.

Abstract: The present invention relates to the fabrication of an optical device; and, more particularly to an electrode for fabricating periodically poled optical fibers and a fabrication method of periodically poled optical fibers using the electrode. To fabricate periodically poled optical fibers for improving the effect of three wave mixing in accordance with the second-order nonlinear optical phenomenon, the periodically poled optical fibers of the present invention is formed by using one or more electrodes with holes or grooves for a period satisfying the quasi phase matching condition between light waves in use. Also, using the electrodes described above, one or more holes or one or more grooves are formed on the surface of the optical fiber around the core in its length direction, and thereby make an optical fiber poled periodically.

Abstract: A compact and easily manufacturable waveguide optical frequency router (10) is provided. The router (10) has a transmit core region (12) and a plurality of receive core regions (14) formed within a slab region (18). The router (10) further includes an array of distributed Bragg deflectors (DBDs) (16) formed within the core regions (12,14) for coupling optical energy (20) between the transmit core region (12) and the receive core regions (14) via the slab region (18). The array of DBDs (16) distributes the optical energy (20) between the receive core regions (14) based on optical wavelength and propagation angle.

Abstract: A tunable optical filter for simulating the waveband spectrums of selected substances. The filter includes an optical waveguide with a core material for transmitting light energy and a nominal core refractive index for the core material. Predetermined periodic variations are formed in the core material of the optical waveguide between the input and output ends that alter the core refractive index of the waveguide at the location of the periodic variations. Depending upon the periodic variations, the waveguide produces a predetermined reference waveband spectrum output that matches the waveband spectrum of a selected substance. A modulator is coupled to the waveguide to selectively modulate the periodic variations to intermittently shift the reference waveband spectrum output to fine tune the filter and reduce signal noise.

Abstract: The present invention provides a fiber Bragg grating system, which employs a linear-cavity fiber laser scheme to develop a high resolution sensor system. The fiber Bragg grating sensor device is located in one end for fiber laser reflecting, and in the other end is a fiber loop mirror. It forms a linear-cavity fiber laser scheme basis. The end for laser output parallel connecting with two fiber Bragg grating filters. Because of the spectrum shift of the fiber Bragg grating sensor when temperature changed, it may detect the optic power reflectivity for the variation of the temperature. Furthermore, it can resolve the temperature up to 10−4° C. theoretically and can be applied for strain and temperature sensing with high precision.

Abstract: 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.

Abstract: A tunable phase mask assembly for use in photoinducing an optical wavelength filter in an optical waveguide. The phase mask assembly includes a phase mask having a length extending between two opposite longitudinal ends. The phase mask has grating corrugations projecting from its surface and distributed with a periodicity along its length. The periodicity of the phase mask is tuned by reversibly changing its length between the two longitudinal ends, such as by compressing or stretching the mask. In this manner, the interference pattern of a light beam passing through the phase mask is also tuned, which allows to control the characteristics of a wavelength filter photoinduced using this phase mask assembly.

Abstract: An optical delay generator includes a waveguide made from electro-optically active material which contains a chirped distributed Bragg reflector. An electric field generated across the waveguide causes the index of refraction within the waveguide to change. A change in the index of refraction results in a change in the point at which light is reflected from the chirped distributed Bragg reflector within the waveguide, thus providing a controllable delay for optical pulses. Optical pulse position modulation is provided by using the optical delay generator to control the delay imparted on each pulse within a stream of equally-spaced optical pulses.

Abstract: A method of forming a complete grating structure on a photosensitive waveguide is disclosed comprising the steps of: (a) writing an initial portion of the grating structure on the waveguide; (b) testing the properties of the initial portion to determine a series of parameters of the initial portion; (c) utilizing the parameters to alter the characteristics of a subsequently written portion of the grating structure to provide for an improved form of grating structure; (d) iterating the steps (a) to (c) so as to form the complete grating structure. The writing can be performed utilizing a coherence pattern formed from the interference of two coherent beams on the waveguide. The characteristics can include the intensity or phase of the subsequently written portion. The testing may include determining the spectral reflectance response of the initial portion or determining the spectral phase delay of the initial portion.

Abstract: Techniques and devices for modulating an optical signal transmitting through an optical waveguide such as a fiber and a planar waveguide by dynamically controlling an adjustable grating formed in a cladding layer of the waveguide.

Abstract: A tunable grating apparatus includes a plurality of grating structures contained within an optical transmission path. A microelectromechanical (MEMS) actuator is operatively connected to each grating structure for changing the separation between the grating structures and tuning the grating to a desired wavelength selectivity. The grating structures preferably form a Bragg grating.