Abstract: An article comprising an alloy exhibiting high magnetostriction in relatively low applied magnetic fields is provided, the alloy capable of being formed in a relatively easy manner and having desirable physical properties. The Co—Fe alloy of the invention exhibits a magnetostriction of at least 100×10−6 in a magnetic field less than 400 Oe, advantageously in a magnetic field less than 100 Oe. The alloy is formed by plastically deforming the alloy, e.g., by cold rolling, to a reduction in cross-sectional area of at least 50%, and then heat treating the alloy to induce recrystallization. This combination of plastic deformation and recrystallization was found to provide desirable grain growth and microstructure. The resultant alloy is useful in a variety of device components, including transducers, frequency filters, signal delay lines, and optical fiber grating devices.

Abstract: In accordance with the invention, an electrical or electronic circuit is provided with one or more components of magnetoresistive material and disposed within the gap of a programmable and latchable magnet. This provides the circuit with programmable and latchable resistivity, particularly useful in transformers, amplifiers and frequency tuners.

Abstract: Aligned Optoelectronic assembly with improved dimensional stability is disclosed. The assembly is carried out with a bonding material, either a solder or an adhesive, which contain insoluble, non-coarsening dispersoid particles. New solder compositions having enhanced mechanical properties are described. Relatively inert particles having a diameter of 5000 nm or less are dispersed in a solder material having an average grain size of approximately 10,000 nm or less to produce such solder compositions. The dispersed particles act as physical barriers in solders substantially impeding the motion of grain boundaries and inhibiting grain growth during thermal and stress cycling which substantially inhibits coarsening. As a consequence, the optoelectronic device assembly according to the invention exhibit substantially improved dimensional stability, with the rate of creep deformation at the joint reduced by a factor of at least two.

Abstract: A tunable chromatic dispersion compensator for optical communication systems is disclosed. An optical grating, such as a fiber Bragg grating, non-chirped, linearly chirped or non-linearly chirped, is coated on its outer surface with a coating have a variable diameter and strained is applied to the fiber. The fiber may be latchably strained so that the grating characteristics may be changed or tuned while avoiding use of a continuous power supply. Various optical networking applications using such dispersion compensating devices are also disclosed.

Abstract: A method for making a chirped grating device capable of a broad bandwith for optical communication systems is disclosed. An intrinsically-chirped optical grating is externally strained to alter the range of chirping. The external strain may be induced by a gradient-generating body bonded onto the length of the fiber grating that may be latchably strained so that the grating characteristics may be changed or tuned while avoiding use of a continuous power supply. Various optical networking applications using such dispersion compensating devices are also disclosed.

Abstract: In accordance with the invention, a tunable optical grating device comprises a grating, which is fixed at both ends to a support frame and is flexed so that a tensile strain induced in the grating reconfigures the resonant wavelength. Typical embodiments include mechanical or magnetic latching arrangements capable of inducing a latchable change in grating periodicity. In typical embodiments programmable and latchable magnets accurately produce a predetermined amount of fiber deflection and tensile strain, thereby producing a latchable wavelength shift with minimal power. The device is especially useful in WDM communication systems for adding or dropping channels, for dynamically gain-equalizing optical amplifiers, for tuning lasers, and for dispersion compensation.

Abstract: An article comprising an alloy exhibiting high magnetostriction in relatively low applied magnetic fields is provided, the alloy capable of being formed in a relatively easy manner and having desirable physical properties. The Co--Fe alloy of the invention exhibits a magnetostriction of at least 100.times.10.sup.-6 in a magnetic field less than 400 Oe, advantageously in a magnetic field less than 100 Oe. The alloy is formed by plastically deforming the alloy, e.g., by cold rolling, to a reduction in cross-sectional area of at least 50%, and then heat treating the alloy to induce recrystallization. This combination of plastic deformation and recrystallization was found to provide desirable grain growth and microstructure. The resultant alloy is useful in a variety of device components, including transducers, frequency filters, signal delay lines, and optical fiber grating devices.

Abstract: The invention provides a device with an improved tunable laser structure, the structure useful with surface emitting lasers and capable of exhibiting desirable latchability. The tunable laser of the invention contains a laser structure having a lower reflector, an active laser region, and an upper reflector. The upper reflector contains a non-moveable reflector portion located adjacent the active laser region and a moveable reflector portion located a spaced distance from the non-moveable reflector portion. A magnetic material is located either on a surface of the moveable reflector portion or on a surface in contact with the moveable reflector portion, and a programmable magnet is located near the magnetic material, the magnet capable of inducing controlled movement of the magnetic material. This movement in turn induces movement of the moveable reflector portion such that the spaced distance between the moveable reflector portion and the non-moveable reflector portion is capable of being adjusted.

Abstract: A tunable chromatic dispersion compensator for optical communication systems is disclosed. An optical grating, such as a fiber Bragg grating, nonchirped, linearly chirped or non-linearly chirped, is strained to alter the dispersion compensator characteristics, preferably with a gradient-generating body bonded onto the length of the fiber grating. The body may be latchably strained so that the grating characteristics may be changed or tuned while avoiding use of a continuous power supply. Various optical networking applications using such dispersion compensating devices are also disclosed.

Abstract: In accordance with the invention, a passively temperature-compensated tunable optical grating device comprises a grating, which is fixed at both ends to a support frame, and is mechanically or magnetically flexed so that a tensile strain induced in the grating reconfigures the resonant wavelength of the grating. Preferred embodiments include at least one waveguide grating, a flexing mechanism capable of inducing a latchable change in grating periodicity and at least one negative thermal expansion component which, upon heating, reduces the strain in the grating so that the temperature-induced wavelength shift is substantially cancelled out. The device can reduce the temperature-dependent wavelength change to less than 0.5 nm/100 deg. C, and preferably less than 0.05 nm/100 deg. C. In a preferred embodiment, the packaging assembly also includes a fine-wavelength adjusting mechanism for post-assembly corrective tuning.

Abstract: The invention is a reconfigurable optical grating device using force from programmable magnets to alter the mechanical strain, preferably a tensile strain, on the gratings so as to induce a latchable change in grating periodicity using a pulse or short-duration current. It includes apparatus for limiting the maximum strain applied to the grating so that the fiber does not fracture, and it provides strain without rotation or twisting of the fiber grating. In preferred embodiment it provides control of magnetic force so as to accurately obtain a predetermined amount of strain and hence wavelength shift in the grating with a minimal amount of electrical power. The inventive structure is useful, e.g. for wavelength division multiplexed optical communication system comprising wavelength channel add/drop devices and/or dynamically gain-equalized amplifiers.

Abstract: The invention discloses digitally tunable optical grating device using force between switchable and nonswitchable magnets to reconfigure the mechanical strain, preferably a tensile strain, or gratings so that a pulse or short-duration current can induce a latchable change in grating periodicity. Preferred embodiments include fiber gratings with magnet gaps dimensioned for limiting the maximum strain applied to the grating and guides for providing strain without rotation or twisting. The magnets provide an accurately predetermined amount of strain and hence provide a latchable wavelength shift in the grating with a minimal amount of electrical power. The device is especially useful in WDM communication systems, particularly for adding or dropping channels and for dynamically equalizing amplifier gain.

Abstract: A programmable and latchable device for wavelength shifting and chromatic dispersion compensating is disclosed. An optical grating such as a Bragg grating, a nonchirped grating, or a linearly or non-linearly chirped grating, is magnetostrictively strained to alter the dispersion compensator characteristics. In a preferred embodiment, a gradient magnetostrictive body is bonded along its length to the fiber grating. In yet another preferred embodiment, a magnetostrictive body is bonded onto the length of the fiber grating, and a gradient generating, programmable and latchable magnet component is placed adjacent the magnetostrictive body. The body is then latchably strained to a desired level by controlling the extent of magnetization in the magnetostrictive material and the magnet so as to induce or enhance chirping characteristics in the grating. Various optical applications using such are disclosed.

Abstract: A temperature-compensated tunable optical waveguide grating device comprises a length of optical waveguide grating including an optical grating region, a guiding tube or frame mechanically coupled to the waveguide at one end of the grating region, and mechanically coupled to the waveguide at the other end of the grating region, a movable element responsive to control signals for applying adjustable strain across the grating region, thereby tuning the grating. The device further comprises a temperature-compensating element for modulating the strain in proportion to changes in temperature, thereby temperature compensating the device. Advantageously the waveguide is an optical fiber and the movable element is a movable magnet.The inventive device can reduce the temperature-dependent wavelength change to less than 0.5 nm/100 deg. C., and advantageously less than 0.05 nm/100 deg. C.

Abstract: In accordance with the invention, a device for controlling alignment between two optical devices comprises a mobile magnet attached to a mobile optical device and a plurality of programmable magnets for moving the mobile magnet (and attached optical device) in relation to a second optical device. In preferred embodiments, the programmable magnets are latchable.

Abstract: A temperature compensated optical fiber grating device comprises a longitudinally extending optical fiber grating having a length and a packaging assembly for the grating comprising a first longitudinally extending body of material having a first coefficient of thermal expansion (CTE) and second and third longitudinally extending bodies of material having CTE's lower than the first CTE. The three bodies are mechanically attached at alternate ends to form a composite structure having an effective negative CTE between two ends to which the grating is attached. The resulting grating device can be made in compact form having an overall length less than 30% more than the grating (and preferably less than 10%) and can reduce the temperature dependent wavelength change in the grating to less than 0.2 nm/100.degree. C. and preferably less than 0.05 nm/100.degree. C. In a preferred embodiment, the packaging bodies include a cylinder enclosing the grating.

Abstract: Magnets are used to control the amount of coupling loss between fibers. The fiber ends are attached to magnets and by controllably magnetizing the magnets, the fibers can be pulled apart or brought closer together to vary the amount of coupling loss. Preferably at least one of the magnets is latchable. The advantage of the latchable version is that a predetermined amount of loss can be latchably set by magnetizing the magnets to a particular level and afterwards no additional power is required to maintain the amount of attenuation. This is advantageous compared to other approaches in which power is required continuously to maintain a particular loss level.

Abstract: A tunable optical grating device that can be digitally and latchably tuned comprises a length of waveguide including a grating region, and a movable body and fixed substrate attached to the waveguide proximal the grating region. The body is movable from a first position to at least a second position, and in some embodiments to a plurality of positions, along the length of the waveguide to apply a mechanical strain to the grating to shift the wavelength response of the device. The movable body is latchable between the various positions along the length of the waveguide to define a latchably tunable device so that a continuous supply of power is not needed to tune the device. The digitally and latchably tunable optical grating device is useful in WDM communication systems, particularly for adding or dropping channels and for dynamically gain-equalizing optical amplifiers.

Abstract: In accordance with the invention, the piezoelectric layer of a SAW device is mechanically coupled to a substrate of temperature-sensitive material having a large coefficient of thermal expansion or contraction. In a preferred embodiment, the temperature-sensitive material is a nickel/titanium alloy having high negative coefficient of thermal expansion of about -200.times.10.sup.-6. The frequency of the device can be tuned by changing the temperature of operation.

Abstract: In accordance with the invention, a tunable laser uses magnets to apply mechanical strain on fiber Bragg grating reflectors or laser cavities in order to induce a change in lasing wavelength. The strain can be tensile or compressive. The tunable laser comprises a laser cavity including a laser material for emitting light in response to stimulating light and two end reflectors one or more of which can be a Bragg grating. In preferred embodiments, latchable programmable magnets vary the grating periodicity and/or cavity length in a controlled, accurate manner so as to achieve desired tuning of the laser over a broad range of wavelengths. The latchable magnets hold the wavelength in the shifted position without the need for sustained power.