Lucent Technologies Inc.

Bell Telephone Laboratories

At&t Bell Laboratories

At+t Corp.

Triquint Technology Holding Co.

Dietrich Marcuse

Herman M Presby

Ivan P Kaminow

Enrique A Marcatili

Thomas Edward Darcie

Thomas Huntington Wood

Leonard G Cohen

Akira Hasegawa

George Ludwig Fischer

Yuji Kodama

Wanda L Mammel

Victor Michael Aquaro

A method and apparatus are disclosed for coupling a multimode laser to a multimode fiber using a multimode tapered structure. The disclosed multimode tapered structure accepts an optical beam having a highly elliptical beam shape and converts the optical beam for acceptance by the circular multimode optical fiber. According to one aspect of the invention, the multimode tapered structure has a tapered form having an elliptical cross section at one end to match the rectangular laser aperture, and a circular cross section at the other end to match the fiber core. The disclosed multimode tapered structure is tapered from a smaller dimension at the input end that matches the dimension of the multimode light source to a larger dimension at the output end that matches the circular core of the multimode fiber. Depending on the selection of the numerical aperture and the length of the multimode tapered structure, coupling efficiencies up to 98 percent may be achieved with the present invention.

Method and apparatus for coupling a multimode laser to a multimode fiber

Disclosed is the use of a polymer material in an optical waveguide structure. The polymer material may be used in either the cladding or the core material of an optical waveguide. The use of polymer material as such is advantageous in that the index of refraction of polymer material varies significantly with changing temperature. The polymer material is subjected to a heating mechanism and/or a cooling mechanism to manipulate the index of refraction as desired.

Waveguide structure using polymer material and method

A low-rate data transmission system and method are disclosed that use the Faraday effect to modulate the polarization state of light traveling in an optical fiber. The resulting change in polarization is used to communicate information over the fiber. The low-rate data transmission system includes a low-rate signal source producing current in a wire coil wrapped around an optical fiber. Information is conveyed in accordance with the present invention by the selectively introducing a polarization change into the light carried by the fiber. Generally, the source light at the input of the optical fiber can be randomly polarized and information is conveyed in accordance with the present invention by the presence or absence of a predefined polarization introduced into the light. The longitudinal magnetic field produced by a current in the coil rotates the plane of polarization of the light, in accordance with the well-known Faraday effect. When the current in the coil is modulated by the signal source, the resulting change in polarization communicates information over the fiber.

Method and apparatus for modulating an optical signal using polarization

An optical attenuator and method, the optical attenuator having a core which is covered by a cladding material with a section of polymer cladding of an identifiable length. The polymer cladding has an index of refraction that varies with temperature. A thermal device such as a thermoelectric heater or cooler is placed adjacent to the polymer cladding to control the temperature of the cladding. The index of refraction of the polymer cladding is manipulated by changing its temperature by supplying power to the thermal device. The index of refraction of the polymer cladding will range from values below and above the index of refraction of the core material. A light wave transmitted through the core will experience a degree of attenuation due to leakage into the polymer cladding material when the index of refraction of the polymer cladding is equal to or greater than the index of refraction of the core. The light wave may be either attenuated or blocked entirely.

Optical attenuator structure and method using polymer material

An optical coupler and method is disclosed in which a polymer material is employed to optically couple a first and second waveguide in a transfer region. In the transfer region, the first and second waveguides are positioned in parallel separated by a specific distance. The polymer material has an index of refraction which varies with temperature. The optical switch device is controlled by adjusting the temperature of the polymer material to obtain a desired index of refraction, thereby resulting in the desired transfer of an optical wave from on waveguide core to another.

Directional coupler and method using polymer material

A Mach-Zender interferometer employing a section of polymer cladding in one branch. The polymer cladding has an index of refraction that varies with temperature. The temperature of the section of polymer cladding is adjusted to cause a corresponding change in the phase of the laser light flowing through the waveguide core bounded by the polymer cladding to effect a desired switching or modulation of the laser light.

Polymer material and method for optical switching and modulation

An optical switch having a straight waveguide core with a lateral waveguide core extending therefrom. A region of polymer material is disposed in the straight waveguide core to deflect optical waves from the first waveguide core into the lateral waveguide core depending on the relative indexes of refraction between the first waveguide core and the polymer material. The temperature of the polymer material is adjusted, thereby adjusting the index of refraction of the polymer material so as to cause the deflection in a switched state, and to allow light radiation to pass through the polymer material in an un-switched state.

Polymer waveguide switch and method

An integrated optical circuit having a turning mirror formed by an end surface of a planar waveguide forms a turning mirror deflector surface. More specifically, the integrated optical circuit includes a planar optical waveguide formed within a cladding layer wherein the planar waveguide has a deflector end surface positioned adjacent to a region, such as a gap. The refractive indices of the planar waveguide and region are in a ratio of no less than approximately 1.3 to provide a desired refractive index discontinuity. This refractive index discontinuity in combination with the positioning of the deflector end surface at an angle relative to an axis extending perpendicular to the direction of the waveguide in the range of 24.degree. and 67.degree. enables an advantageous deflection of an optical signal.

Integrated optical circuit having planar waveguide turning mirrors

Measuring and setting techniques for relative component orientations and separations is accomplished by projecting a coherent light beam into one end of a gap formed between facing surfaces of adjacent components. This light beam projection causes a corresponding light ray pattern to be projected out of an opposite end of the gap. The arrangement of light rays in the resulting pattern is indicative of the relative positions of, and distance between, the facing surfaces. Such a projected pattern is used for determining the relative positions between adjacent components, alone, or as feedback for adjusting such component positions to achieve a desired orientation and/or separation distance between the components.

Optical reflection methods and apparatus for aligning communication

An exemplary embodiment of an acousto-optic planar waveguide modulator includes a planar waveguide structure with an input section connected to a multimode section connected to an output section. The input and output sections have structures for propagating an optical signal in a first transmission mode. The multimode section has a structure in which an optical signal can propagate in the first transmission mode and a second transmission mode. A surface acoustic wave source is used to direct a surface acoustic wave at the multimode waveguide section to cause a periodic change in the refractive index for coupling optical signal energy between the even and odd transmission modes. As a consequence, power of an optical signal propagating in the even transmission mode is transferred to the odd transmission mode. This power transfer causes an attenuation of the optical signal propagating in the even transmission mode from the multimode section to the output section. Such attenuation can be varied in accordance with a second signal to modulate the optical signal by correspondingly varying the surface acoustic wave energy to produce a modulated optical signal. Further embodiments modulate optical signals propagating in single mode waveguides having their transmission modes evanescent field coupled to respective transmission modes of the planar multimode waveguides.

Acousto-optic planar waveguide modulators

An acousto-optic silica optical circuit switch that selectively routes signals to one of two outputs includes a surface-acoustic-wave source and a coupler waveguide structure formed within silica glass. The waveguide structure includes a single mode input section connected to a multimode section connected to first and second single mode output sections. The first output section has a structure capable of accepting power from an optical signal propagating in a first transmission mode of the multimode section, and the second output section has a structure capable of accepting power from an optical signal propagating in a second transmission mode in said multimode section. In operation, RF excitation is selectively provided to the SAW source to selectively cause coupling of the first and second transmission modes in the multimode section. As a consequence, an optical signal launched in the input section propagates through the multimode section to the first output section in the first transmission mode of the waveguide structure, or alternatively, such launched optical signal is coupled to the second transmission mode in the multimode section such that its power is transferred to the second transmission mode to propagate into the second output section.

Acoustic-optic silica optical circuit switch

Efficient coupling between multimode optical fibers and optical devices, such as optical detectors and light emitting diodes, is realized by means of a coupling arrangement comprising a length of homogeneous glass fiber, terminated by a convex microlens. One end of the glass, whose length is greater than the focal length of the microlens, is fusion-spliced to the multimode fiber. The convex microlens is formed at the other end of the homogeneous glass member.

Lens structure for focusing the light emitted by a multimode fiber

In external modulation, a modulated light signal is shaped to decrease pulse transition times resulting in less chirp. Accordingly, the modulated signal travels greater distances with less pulse distortion over an optical medium. For an integrated-type of external modulator, chirp is reduced further by using a laser modulator coupled to multiple complementary output ports.

Method and system for reducing chirp in an optical cummunication system

Communication between an upstream point, such as a TV-source headend followed by a fiber optic line, and a number of downstream points, such as coaxial cable connected subscriber locations, is achieved by wavelength or frequency demultiplexing a spectrum of downstream radio-frequency signals with a surface-acoustic-wave (SAW) demultiplexer-multiplexer and distributing the demultiplexed signals to the downstream points, for example through the cables.

Communication systems using passive RF routing

In soliton optical fiber communication systems that comprise a multiplicity of spaced-apart intermediate non-electronic amplifiers, pulse arrival time jitter can be substantially reduced by incorporation into the transmission path of spaced-apart bandwidth-limiting elements. Exemplarily, the bandwidth-limiting elements are optical filters of bandwidth B.sub.f, with a filter associated with each intermediate amplifier, and with B.sub.f chosen to fall within the range B.sub.sol (N.sub.f /3).sup.1/2, where B.sub.sol is the FWHM spectral width of the soliton pulses, and N.sub.f is the number of intermediate filters in the system. More generally, the bandwidth-limiting elements are selected such that &gt;.delta.t.sup.2 &gt;, the variance of the jitter, is at most 90% of the variance associated with an, otherwise identical, comparison system that does not contain the bandwidth-limiting elements. Systems according to the invention thus can overcome the Gordon-Haus limit on the bit rate/distance product.

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Lincroft, NJ, United States of America

Dietrich Marcuse