Abstract: A system and method are used for pulse to pulse dose control in an illumination system, used, for example, in a lithography or a maskless lithography machine. The system and method can be used to decrease effective laser pulse-to-pulse variability in lithographic lasers, allowing adequate dose control using a minimum number of pulses (e.g. as little as one pulse).

Abstract: This invention describes a method for controlling attenuation for a variable optical attenuator (VOA) inserted in an optical path of an optical signal propagating in an optical network, comprising the steps of measuring power of the optical signal at the VOA; comparing the measured power with a target power; and if the measured power differs from the target power, changing the attenuation of the VOA in one or more variable size intervals (VSI) so that the power of the optical signal substantially equals to the target power, wherein the VSI being a function of the measured power and target power.

Abstract: A device for attenuating cladding modes in a single mode optical fiber is disclosed. The device comprises two supports, each equipped with spaced apart corrugations. The optical fiber lies transversely across the corrugations and the two supports are clamped together to impart micro-bends to the optical fiber. The resulting micro-bends provide excellent cladding mode attenuation and the spacing of the corrugations and support members can be adjusted so that the core modes are not attenuated.

Abstract: A waveguide type variable optical attenuator has: a substrate; two optical circuits that are in parallel formed on the substrate, each of the optical circuits including two couplers that conduct the branching and coupling of light and are connected to the input port and output port of light and two waveguides through which the two couplers are connected; a polarization maintaining fiber one end of which is connected to the output port of one of the two optical circuits and the other end of which is connected to the input port of the other of the two optical circuits while being twisted 90°; and a heater that is provided around neighboring waveguides of the two optical circuits such that the neighboring waveguides share heat to be generated by the heater.

Abstract: There is provided an electronic security system for a perimeter structure that incorporates a fiber optic cable secured to the perimeter structure. Typically the perimeter structure is a fence. A light pulse is transmitted down the fiber optic cable. Mechanical attenuation devices disposed at various locations along the fiber optic cable are responsive to intrusion attempts. The mechanical attenuation devices produce measurable attenuations to the light pulse. Using backscattering light detection technology an intrusion attempt and the location of an intrusion is detected.

Abstract: An improved cantilever beam optical switch methodology which provides the function of a variable optical attenuator (VOA). A small degree of intentional misalignment of the waveguide will create different levels of optical attenuation. By finely controlling the misalignment of a selected switched position, a single device may be realized that will provide the functions of both switching and attenuating or just attenuation alone. The optical MEMS device utilizes a latching mechanism in association with a thermal drive actuator for aligning a cantilever beam platform. The integration of the switching function and the VOA function reduce the optical loss which is otherwise unavoidable when the inevitable alterative of a separate switch and a separate VOA must necessarily be employed. The resultant improved device can also be applied for correcting the difference in optical intensity created by the manufacturing tolerances inherent in the fabrication of array waveguide gratings.

Abstract: A variable optical attenuator is constituted of input/output optical systems, a birefringent member provided at output sides of the input/output optical systems, a liquid-crystal member capable of individually varying polarizing states of input beams exiting the birefringent member, and a reflection member which reflects light passing through the liquid-crystal member, to thereby cause the light to return to an output lens of the input/output optical systems by way of the liquid-crystal member and the birefringent member. Thus, there can be provided a variable optical attenuator which is more compact and less expensive than a related-art variable optical attenuator.

Abstract: A first waveguide holding member has a first transverse surface region and a first optical waveguide having an end terminating at the first transverse surface region. A second waveguide holding member has a second transverse surface region which confronts the first transverse surface region of the first waveguide holding member and a second optical waveguide having an end terminating at the second transverse surface region. A guide member is operatively coupled to the first and second waveguide holding members and guides the first waveguide holding member in a transverse direction relative to the second waveguide holding member so as to selectively optically couple and decouple the ends of the first and second optical waveguides.

Abstract: An arrangement for controlling the transmission of a light signal is disclosed. The arrangement includes a first fiber optic line for transmitting the light signal and a light receiving unit operatively coupled to the first fiber optic line so that the light signal is received by the light receiving unit. The light receiving unit is operative to refract the light signal so that the light signal is substantially prevented from being transmitted through the light receiving unit if an intensity level of the light signal has a predetermined relationship with an intensity threshold level.

Abstract: Disclosed is herein an optical switch, which has advantages of an MEMS optical switch and a waveguide optical switch including a small electric power consumption, an easy packaging process, and a fast switching speed. The optical switch includes an input waveguide connected to an input optical fiber through which an optical signal is inputted, and a plurality of output waveguides connected to a plurality of output optical fibers through which the optical signal is outputted. An actuator is positioned between the input waveguide and the output waveguides, and has an MEMS structure including a fixed part and a moving part connected to the fixed part by a spring to move by a predetermined force.

Abstract: One aspect is a method for controllably attenuating the beam of light (108) coupled between incoming and outgoing optical fibers (106) by misaligning minor surfaces (116a, 116b) included of an optical switching module (100). Misalignment of the mirror surfaces (116a and 116b) causes only a portion of the beam of light (108) propagating along the incoming optical fiber (106), which is less than when the light beam deflectors' mirror surfaces (116) are precisely aligned, to propagate along the outgoing optical fiber (108). Thus, the optical switching module (100) controllably attenuates the beam of light (108) coupled between the incoming and the outgoing optical fibers (106). Another aspect is a variable-optical-attenuator (“VOA”) (212) that includes an optically reflective membrane (222) upon which the beam of light (108) impinges. Application of an electrostatic field between an adjacent electrode (228) and the membrane (222) deforms the membrane (222) thereby attenuating an impinging beam of light (108).

Abstract: The attenuation from connectors to the interaction region of the light signal with the microwave can be reduced, and the bandwidth can be improved in an optical waveguide device, in which a space between strip lines on a ceramic substrate at one end of the strip lines connected to first and second input sections is adapted to be narrower than a space between the strip lines at the other end of the strip lines connected to first and second electric connectors.

Abstract: A monolithic optical coupling module for coupling a light beam is disclosed. The optical coupling module has a light beam input portion, a light beam output portion and at least one integrally formed light beam attenuator between the light beam input portion and the light beam output portion. The monolithic optical coupling module may be unitarily fabricated of a moldable polymeric material. The light beam attenuator may be a roughened surface or a roughened internal portion. A method for forming the monolithic optical coupling module is also disclosed.

Abstract: An electric-optic modulator includes a block of crystal having electro-optic properties, the block extending lengthways along a long axis and having a light guide which extends between a light guide input and a light guide output. An electric modulation signal acts on an interaction zone of the block via coplanar electrodes together with the light guide via a dielectric layer. The electrodes are disposed on a main long face of the block and the interaction zone is elongated more or less along the long axis. The light to be modulated arrives through an input optical fiber which is connected to the light guide at the light guide input on a first face of the block. The modulated light leaves the modulator through an output optical fiber connected to the light guide output on a second face of the block. The first face and the second face are one single face (D) which is parallel to the long axis.

Abstract: An improved device, which may act as a variable attenuator, changes the optical intensity of an optical signal by moving a platform onto which a light transmissive structure such as a waveguide is disposed. The light transmissive structure is positioned and aligned to receive an optical signal and positioned and aligned to transmit the optical signal. By moving the light transmissive structure into a position of reduced alignment with an input source, the light transmissive structure may receive less or none of the optical signal, thereby attenuating it. Alternatively, by moving the light transmissive structure into a position of reduced alignment with an output structure, the light transmissive structure may transmit less or none of the optical signal, thereby attenuating its transmission.

Abstract: An optical coupling assembly having an optical receiver that exhibits extended dynamic range, and, more particularly, an optical receiver that is integrated with a Variable Optical Attenuator (VOA) to extend the dynamic range of the receiver.

Abstract: An attenuating device for attenuating optical power of a light beam, comprises an at least partly absorbing element adapted to receive and attenuate the optical power of the light beam, and a supporting element for supporting on at least one side the at least partly absorbing element. The at least partly absorbing element comprises at least one layer coated or evaporated on the supporting element with an increasing, decreasing, or varying thickness. The supporting element is provided with a material having a crystalline structure to provide compensation to a local heating in the at least partly absorbing element resulting from absorption of the light beam.

Abstract: A variable optical attenuator comprises an incoming fiber for propagating an incoming light beam, a mirror for reflecting the incoming light beam as a reflected light beam and an outgoing fiber for propagating as an outgoing light beam at least one part of the reflected light beam. The light intensity of the outgoing light beam is determined by the angle of reflection at the mirror. The angle of reflection at the mirror is adjusted by an actuator for rotating the mirror. The actuator comprises a plate, a coil, a housing and permanents magnets. The mirror and the coil are fixed on the plate. The housing supports the plate so that the plate is able to rotate around a rotation axis, which is included on a predetermined plane. The permanent magnets are fixed on the housing and generate predetermined magnetic flux density along the predetermined plane. When a driving current is supplied to the coil under the predetermined magnetic flux density, a Lorentz force occurs at the coil so as to rotate the coil.

Abstract: A variable optical attenuator with tunable wavelength selectivity includes at least two reflectors disposed parallel to each other at a predetermined angle from an optic axis and driving units connected to said at least two reflectors for allowing the reflectors to move back and forth in a direction perpendicular or parallel to the optic axis or to revolve centering on an axis perpendicular or parallel to the optic axis. Since the variable optical attenuator of the present invention serves as a variable optical attenuator and, at the same time, as a tunable wavelength filter, problems of insertion loss and optical alignment that might be caused by separately installing a variable optical attenuator and a wavelength filter can be effectively prevented. Moreover, by implementing the variable optical attenuator and the tunable wavelength filter by using a single device, the size of a system using the optical attenuator can be reduced.

Abstract: A variable optical attenuator for providing a new light attenuation mechanism based on using at least one of tilted mirrors to change and control the beam direction of reflected light beam toward output optical port in a two dimensional light path configuration is demonstrated to achieve the light attenuation in terms of changing and controlling the coupling loss among input optical port, reflective tilted mirrors, and output optical port. The tilted mirror is supported and connected by a suspended flexure spring at one side. This suspended spring is connected with tilted mirror at one side and is anchored on a substrate at the other side via a post (or a pivot). When the tilted mirror is driven by an actuator to generate movement including rotational mirror deflection and parallel mirror shifted displacement, the reflected light beam path is changed according to the particular mirror positions. The attenuation value is modified and controlled by the coupled light of reflected light beam to output port.

Abstract: A method and apparatus are disclosed for adjusting the phase of an optical signal by varying the path length of the optical signal using one or more moveable mirrors. The phase adjustment techniques of the present invention may be employed in various optical devices, including 1×n optical switches. The position of the mirrors may be controlled, for example, using micromachined control elements that physically move the mirror along the lightpath. An exemplary 2-by-2 optical switch includes two waveguides configured to include a coupler region. A mirror is positioned at the output of each waveguide. The position of at least one of the mirrors may be adjusted along the optical path and the mirrors reflect the light exiting from the end of the waveguides back into the same waveguide after an adjustable phase delay due to the round trip through an adjustable air gap between the waveguides and corresponding mirrors.

Abstract: There is provided an optical module capable of improving assembling efficiency and reducing the number of parts to reduce production costs, and an optical connector having the same. The optical module has a holder 3, a lens 12 and a diffraction grating 13 for damping the quantity of light. The holder 3, the lens 12 and the diffraction grating 13 are formed of a resin material so as to be integrated with each other. The diffracting grating 13 is designed to prevent high-order diffracted light beams from being coupled with an optical fiber 8.

Abstract: An optical fiber system includes an optical fiber light transmission system having a light path therethrough, and a filter module positioned to controllably place light filters into the light path of the optical fiber light transmission system. The filter module includes a movable support on which light filters are mounted, and a drive mechanism operably connected to the movable support to controllably move the at least one light filter into and out of the light path. The drive mechanism is operated to move the light filters into or out of the light path.

Abstract: The present invention relates to a type of optical fiber grating having an azimuthal refractive-index perturbation. The optical fiber includes a fiber grating that has a plurality of grating elements formed therein. At least one of the grating elements has a spatially varying index of refraction that varies azimuthally about the centerline of the optical fiber. The fiber grating acts as a band-stop optical spectral filter. In addition, since fiber-cladding modes are weakly-guided modes, their power can be easily dissipated by scattering, bending, stretching, and/or rotating the optical fiber. Multiple configurations of these gratings within an optical fiber are given. Devices are presented which can dynamically attenuate, tune, switch, or modulate the wavelength spectral characteristics of an optical signal.

Abstract: Optical devices for adding/dropping an optical signal with a particular wavelength are disclosed. According to embodiment, a reflection channel module including a grin lens and a bandpass filter is employed to transmit the optical with a particular wavelength and reflect all other channel signals. The transmitted signal is regulated by an optical regulator (e.g. variable optical attenuator) before it is output from the device via a grin lens. As a result, a regulated channel can be dropped or added depending on an application.

Abstract: A method of generating a pulse width modulated (PWM) signal receives digital demand data comprising at least one more significant bit and at least one less significant bit. The PWM signal comprises a sequence of one or more frames, each frame comprising a plurality of PWM pulses whose duty cycle is substantially governed by the at least one more significant bit. At least one of its PWM pulses is selected to have its duty cycle modified in response to the at least one less significant bit. Each of the at least one less significant bit uniquely mapping onto the at least one selected PWM pulse of the frame. An apparatus operable according to this method includes an optical attenuator whose optical attenuation is dependent upon its temperature and in which the temperature and, hence, the attenuation is controlled using the above PWM signal.

Abstract: In one form, one or more micropumps and optical micro-detectors are on a substrate, ideally many per square centimeter, each detecting fluid moved by its pump. A second form has many waveguides and, intersecting each, a fluid chamber controlling radiation in the guide; the device is best immersed in a fluid that moves in and out of chambers, intercepting radiation to yield position data—transmitted e.g. wirelessly for external reception. The device can be a chip in a live creature (e.g. implanted, or in blood); data go to a wireless receiver. Each guide ideally couples to a radiation source and detector. In a third form a membrane deflects a radiation-interacting fluid in a plenum; liquid moves between the plenum and a tube. The plenum cross-section is many times the tube's; radiation in the tube is monitored. Deflected liquid in the tube controls specimen movement to and from the tube.

Abstract: In accordance with the invention, a high-resolution variable optical delay line comprises an optical switch, such as an optical micromechanical mirror switch, and an array of delay fiber paths. Each delay fiber path in the array comprises a region where the fiber is curved differently from the other fibers in the region and a reflector. Each fiber path advantageously comprises other regions where the fiber is essentially parallel to the other fibers in the region. Each fiber is curved differently from the others in order that the fiber paths each provide a different delay.

Abstract: An optical device including dynamic channel equalization is provided. In an exemplary multiplexer or line amplifier configuration the device includes a plurality of separate optical paths, each of which receiving a separate group of optical signals. Each group of optical signals is provided to an associated variable optical attenuator. Separate inputs of an optical combiner are each coupled to an output of an associated one of the variable optical attenuators. The optical combiner has an output providing the separate groups of optical signals in an aggregated form on an aggregate optical signal path. An optical performance monitor is coupled to the aggregate optical signal path, and is configured to detect an optical signal to noise ratio of each of the separate groups. The monitor supplied a feedback signal to corresponding ones of the variable optical attenuators for adjusting a respective attenuation associated with each of the attenuators in dependence of the detected optical signal to noise ratios.

Abstract: An optical waveguide device used as, for example, a variable optical attenuator or an optical switch includes: a substrate; a Mach-Zehnder interferometer that is provided on the substrate and that includes first and second waveguide sections interposed between a pair of branches; a heater that includes a conductive thin-film formed at a position corresponding to the first waveguide section and that, by emitting heat, heats the first waveguide section and thus causes a phase shift in the optical signal propagated in the first waveguide section; and a resistor connected, in series with the heater, to a power supply which supplies power to the heater. The resistor has a temperature coefficient of resistance that is lower than that of the heater. The waveguide device is preferably formed as a device having a silica glass waveguide structure.

Abstract: An integrated optical dynamic channel equalizer that can be employed to equalize the channel gain level in a WDM transmission line and monitor the optical channel performance. The device consists of a circulator, a dynamic gain equalizer chip and a controller. Due to the simplicity of the dynamic gain equalizer chip, which includes one 1×n multiplexer/demultiplexer, an n-channel variable optical attenuator array (VOA-n), a partially transparent dielectric reflective means and an n-channel detector array, the device is very compact and can be fabricated at low cost. By placing a quarter wave plate between the n-channel variable optical attenuator array and the partially transparent reflective means in the dynamic channel equalizer chip, the device can be rendered polarization insensitive.

Abstract: The intensity of signals in optical networks can be controlled using a variable optical attenuator (VOA). The present invention is a VOA that is particularly well suited for optical networks, for example to provide channel-by-channel normalization of gain control of wavelength division multiplexed signals. The inventive VOA includes a waveguide having an electro-optical material and electrodes that produce an electric field within the electro-optical material when a voltage difference is applied to the electrodes. The electro-optical material can either be a substrate or can be a layer deposited on a substrate. In an alternative embodiment, a polarization independent VOA is formed from a waveguide that includes two, end-to-end waveguides. In one embodiment, a 90 degree polarization rotator is provided between the two waveguides. In another embodiment, each of the two waveguides has a different electro-optical material selected to selectively pass one of two 90 degree polarizations.

Abstract: A variable optical attenuator includes a first lens, a MEMS device, a second lens, and a wedge. The first lens is configured to collimate an input light received on a first port and focus an output light on a focus point proximate to a second port. The MEMS device includes a reflection surface having a tilting angle thereof controllable by a control variable. The second lens has a focus point positioned proximate to the reflection surface of the MEMS device. The wedge is positioned between the first lens and the second lens and is configured to refract the input light received from the first lens to enter the second lens and refract the output light received from the second lens to enter the first lens.

Abstract: Configurations for optical waveguide crossings are described. In one exemplary implementation, an optical chip includes waveguides integrated on the optical chip. The waveguides have varied widths dependent upon how many waveguides each of the waveguides cross with respect to each other. In another exemplary implementation, voids are inserted between waveguides in the vicinity of waveguide crossings of an optical device. The voids are configured to reduce optical losses in waveguides that have more waveguide crossing while simultaneously increasing optical losses in waveguides that have fewer waveguide crossings. Accordingly, the overall optical losses between the waveguides are generally equalized with respect to each other.

Abstract: A small optical device which has low power consumption and which is excellent for integration, and which has a variable optical attenuation function which features proper polarization dependence over the entire wide variable optical attenuation range is provided. In the optical device, an optical circuit including a core and a cladding that covers the core is formed on a substrate. An optical element is movably disposed inside a groove provided in the substrate so as to traverse the core, and includes a plurality of optical attenuation elements having different light attenuation amounts. By moving the optical element by an actuation function portion provided on the optical circuit, the attenuation amount of signal light that propagates through the optical circuit is changed.

Abstract: In a preferred embodiment, a motorized variable optical attenuator comprises an input fiber collimator; an output fiber collimator disposed substantially along the first collimator; and a right-angle reflector movable relative to the input collimator and the output collimator along a translation direction forming a non-zero angle with a direction of a light beam emitted by the input collimator. The reflector comprises two mutually-perpendicular reflective surfaces for sequentially reflecting the light beam emitted by the input collimator to the output collimator. A variable attenuation imparted by the attenuator on the light beam is determined by a position of the reflector relative to the input collimator and the output collimator, along the translation direction. The reflector preferably comprises a right-angle prism adhered to a nut mounted on a threaded axle driven by a stepper motor. The attenuator can achieve stable, ripple-free attenuation characteristics at insertion losses beyond ?40 dB.

Abstract: Disclosed is an MEMS variable optical attenuator comprising a substrate having a planar surface, optical fibers having an optical signal transmitting end and an optical signal receiving end, respectively, coaxially arranged on the substrate, a micro-electric actuator arranged on the substrate for providing a driving stroke along a direction perpendicular to an optical axis of the optical beam, at least one lever structure arranged on the substrate for receiving the driving stroke of the micro-electric actuator at a first end thereof and transferring an amplified displacement distance to an optical shutter through a second end thereof, an optical shutter arranged on the substrate and connected to the second end of the lever structure so as to be moved by the amplified displacement distance, thereby being displaced to an attenuation position of the optical beam.

Abstract: A fast tunable optical filter with unique selection means, capable of being monolithically integrated on silica or semiconductive wafers, includes a frequency routing device (FRD) for receiving up to P input optical signals and responsively providing up to Q outputs, where P and Q are integers greater than or equal to one, at least one input selecting device for selectively coupling up to P optical signals to the FRD, and at least one output selecting device for selectively inhibiting up to Q outputs of said FRD.

Abstract: Disclosed is a retro-reflective type optical signal processing device and method, particularly to a device includes a set of optical mirror planes with retro-reflective type layout and configuration, and a set of micro-shutters controlled by microelectromechanical actuators, whereas the optical signals in propagation can be blocked or partially blocked in terms of the position of said a set of micro-shutters corresponding to the optical signal transmission path, thereby the method of said approach to determine the range of attenuated optical signal is a variable optical attenuation function demonstrated by present invention. Such a retro-reflective type optical signal processing device and method further comprises a set of three reflective mirrors and micro-shutters with reflective mirrors. Thereby this device has the capability to switch 2 sets of retro-reflected optical light transmission paths, the method of said approach is a demonstration of 2×2 optical switching function.

Abstract: A variable optical modulator for optical communication systems using a tunable dynamic grating comprises a gel or membrane layer attached adjacent to a prism communicating light to/from the optical communication system. A substrate has a plurality of individually addressable electrodes and drive means for providing regulated excitation voltage to each of the plurality of electrodes, thereby generating a wave pattern on a surface of the gel or membrane superimposed on an initial state of the gel or membrane layer.

Abstract: A variable optical attenuator has a first movable waveguide support and a second waveguide support that include first and second waveguides, respectively, such that the first and second waveguides are aligned for propagating an optical energy. An electrically driven actuator positions the movable waveguide support for coupled, optical misalignment relative to the second support to achieve a desired optical attenuation value. The movable waveguide support may be in a cantilevered configuration in which a distal end extends over a surface having an electrode. In this example, applying a drive signal to the electrode deflects the movable support such that the signal coupled between the first waveguide to the second waveguide is attenuated. The drive signal may be set to achieve a desired value for an electrical parameter that varies with the position of the movable waveguide support.

Abstract: An optical attenuator (8) includes an input port (1), an output port (4), a fixed reflector (2), a movable reflector (3), two detecting means (6, 7) and a driving device (5). The input port includes a first collimator (13) and a filter (10) attached to the first collimator. The output port includes a second collimator (41) and a splitter (42) connected to the second collimator. Input signals are transmitted from an input fiber (11) through the first collimator and then pass through the filter. The signals passing through the filter are directed by the fixed and the movable reflectors to the second collimator. The angular position of the movable reflector, which is driven by the driving device, determines the proportion of the signals. reflected by the reflectors that are received by the second collimator, which determines the size of the output signals transmitted in an output fiber (421).

Abstract: An optical threshold device including an input, an output, first and second radiation guiding branches, each branch having first and second terminals, at least one of the first and second branches having a non-linear optical element, first and second optical couplers, at least one of the first and second optical couplers having an asymmetric optical coupler, the first optical coupler configured to split an input signal of radiation from the input into a first radiation portion propagating through the first branch and a second radiation portion propagating through the second branch, the second optical coupler configured to combine the first and second radiation portions from the second terminals of the first and second branches, respectively, into an output signal at the output, wherein the non-linear optical element produces a phase shift between the first and second radiation portions and wherein the first and second radiation portions interfere at the second coupler in response to the phase shift.

Abstract: An optical dynamic gain equalization filter (DGEF) comprises a planar arrangement of preferably “perfectly sampled” (or alternatively oversampled) waveguide grating routers (WGR's) connected by individual optical paths each containing a Mach-Zehnder interferometer operated in a push-pull fashion so that a positive phase change in one interferometer arm and a corresponding negative phase change in the other interferometer arm produces a desired change in attenuation while, at the same time, the overall phase of the optical signals after passing through the Mach-Zehnder interferometer is kept constant with respect to the adjacent paths. Alternatively, the above-described arrangement is effectively “cut in half”, and its size effectively also reduced accordingly, using a mirror placed at the midpoint of the device and an appropriate circulator to separate the input and output optical signals.

Abstract: Unique multi-diffraction structures using electronically controlled Bragg diffraction devices such as acousto-optic (AO) devices to accomplish optical beam attenuation control functions. These variable optical attenuator (VOA) modules can be fully inertialess as they can use electronically programmable sub-microsecond speed AO devices to implement optical gain controls. These VOAs deliver desirable capabilities in one optically reversible unit, making high dynamic range, low loss, high power handling, ultra-fast, high optical isolation, broadband operation, self-aligning robust modules. These VOAs can be made essentially independent of the optical polarization of the incident light by the use of a unique fixed waveplate compensation technique within the VOA configuration that suppresses polarization dependent loss. Broadband gain control operation over several wavelengths can be achieved by controlling the frequency and electrical drive power of the chosen frequencies feeding the acousto-optic devices.

Abstract: In a light attenuator or its attenuating method, a nonlinear optical material and an aperture section are placed respectively on a same optical axis, between a receiving optical finder and a sending optical fiber. The nonlinear optical material receives and refracts an input light outputted from the receiving optical fiber. The aperture section has an aperture, receives the light having passed through the nonlinear optical material, and outputs constant output light to the sending optical fiber by only allowing only a part of the light to be outputted from the aperture.

Abstract: A waveguide device has an input waveguide, a plurality of output waveguides, a channel waveguide array, an input slab waveguide, and an output slab waveguide. The output slab waveguide connects an output end of the channel waveguide array to the output waveguide, and has optical input/output characteristics set to given ratios for the output waveguides with respect to the input waveguides. The waveguide device is capable of adjusting signal levels output from the respective waveguides without the need for circuit parts for compensating for loss differences and also the need for a process of highly accurately attaching parts.

Abstract: An optical attenuator has first and second lenses provided individually on the respective end faces of first and second optical fibers that are opposed to each other across a space, and a shutter plate interposed between the lenses. The distance between the shutter plate and the second lens and a mode-field radius of propagating light on the second-lens-side surface of the shutter plate are set so that the respective signs of the real and imaginary parts of an evaluation function, representing a diffraction pattern of the propagating light that propagates from the first optical fiber to the second optical fiber, are inverted 60 times or more when a variable of the evaluation function is changed within an evaluation range.

Abstract: Implementations of a polarization control method and apparatus are provided. In one implementation, a device uses super-polished squeezing surfaces to apply pressure against a polyimide coated fiber thereby minimizing micro-bending effects that cause losses in the fiber. Special control circuitry may be used to maintain a driving source of piezo-electrics that control the squeezing surfaces at a resonant frequency, thereby minimizing the voltages needed to drive the piezo-electrics.

Abstract: An optical attenuator (100) has an optical attenuation fiber (1) doped with cobalt. Two ferrules (2A), (2B) retain the optical attenuation fiber therein. Two butting ends of the ferrules are enclosed in a flange (6), which is received in a front end of an interconnection housing (7). An alignment sleeve (4) retains a rear end of the rear ferrule and is enclosed in a rear end of the interconnection housing. A latch (8) engages with the rear end of the interconnection housing. A plug housing (9) engages with the front end of the interconnection housing. A cover (10) then attaches over all the aforesaid components. A front end of the front ferrule is exposed outside the cover, for connecting with a complementary optical connector.