Lucent Technologies Inc.

At+t Corp.

At&t Bell Laboratories

American Telephone and Telegraph, Co.

Edward J Laskowski

Charles H Henry

Yuan P Li

Henry H Yaffe

Christi Kay Madsen

Michele A Milbrodt

Weyl-Kuo Wang

Jaya Bilakanti

Edwin Arthur Chandross

George J Zydzik

Joseph Shmulovich

Rose Fasano Kopf

Arturo Hale

Valerie Jeanne Kuck

Daryl Inniss

Raymond A Cirelli

Ronald Edward Scotti

Dirk Joachim Muehlner

Catherine Wolowodiuk

Cecilia Y Mak

Douglas R Dykaar

Annjoe Golangco Wong-Foy

Ulrich D Keil

Renen Adar

In accordance with the invention, a high speed thermo-optic phase shifter comprises a length of optical waveguide including a waveguiding core of a first material having an index of refraction nand a first order temperature dependence |dn/dT| and, optically coupled to the core, a length of a second material having an index npreferably greater than the core (n&#x3e;n) and a first order temperature dependence |dn/dT| than the core (|dn/dT|&#x3e;|dn/dT|). Advantageously, the length of second material is adiabatically tapered at both ends. Upon heating, as by a resistance heater, the second material changes the optical pathlength by an amount predominantly determined by |dn/dT| providing faster switching speed. In a preferred embodiment, the core comprises silica, and the second material comprises silicon to produce switching speeds up to a few hundred MHz.

High speed thermo-optic phase shifter and devices comprising same

The present invention includes a MZI comprising a pair of folded waveguides disposed between a pair of couplers. Each folded waveguide comprises a pair of segments intersecting at a reflector. The respective reflectors are different distances from the couplers to provide a major portion of the differential path length between the two arms. In a preferred embodiment, the reflectors are polysilicon mirrors and can be formed by etching through the intersecting waveguides and depositing polysilicon. The result is a compact MZI that can be used as a multiwavelength reference for a laser light source on a common silicon optical bench chip.

Compact mach-zehnder interferometer and wavelength reference employing

The thermo-optically controlled optical couplers wherein the coupling region between the waveguides in the coupling section is filled with a material having a high dependence of refractive index on temperature thus making the thermo-optic control means more efficient and allowing a greater range of adjustment in the coupling coefficient for a given temperature change.

Tunable directional optical waveguide couplers

In accordance with the invention, arrays optical sources are combined in a multilevel planar optical waveguide structure for insertion into an optical fiber laser. The basic element of the combiner is a planar array of multiple waveguides which converge and are gradually tapered to a single output waveguide. A plurality of such elements integrally formed on successive cladding layers provides a high power stack of vertically aligned outputs. An arrangement is described for using such apparatus in the amplification of optical communications signals.

Apparatus for pumping an optical fiber laser

An optimized waveguide structure enables the functional integration of various passive optic components on a single substrate. The optimized waveguide structure is characterized by a thicker core layer than used for square core waveguides and a core width that changes according to different functional regions of the optic circuit within which it is incorporated. The height (H) of the waveguide core is determined by the thickness of the core layer defined during the fabrication process and is ideally uniform across the circuit. The width (W) of the core, however, is changed between functional regions by the photo-lithographic mask and the chemical etching during the fabrication process. By way of example, an optimized waveguide structure for a P-doped silica planar waveguide with a .DELTA. approximately 0.6% for wavelength .lambda.=1.2-1.7 .mu.m, has a single uniform height of H=6.7 .mu.m and a width that changes between W=4 .mu.m in a coupler region, W=5.5 .mu.m in a bend region, W=9 .mu.m in a fiber coupling region, and W=10 .mu.m in a phase grating region of a Dragone router. Adiabatic tapers are used as transition regions between regions of different core widths.

Optimized waveguide structure

The present invention relates to a waveguide taper. The waveguide taper has a first end and a second end for being coupled with a fiber. The core has an overall width that progressively increases from the waveguide end toward the fiber end such that the width of the fiber end of the taper corresponds to the diameter of the core of the fiber. Side-gaps are disposed in the sides of the core and extend into the core but not across the entire width of the core. The depth of the side-gaps progressively increases from the waveguide end to the fiber end of the taper. In one embodiment, the side-gaps may be aperiodically and/or randomly disposed along the length of the taper and the side-gaps can be disposed at different angles to a direction of light propagation along a length of the core.

Side-gap mode tapering for integrated optic waveguides

In accordance with the invention, a new type of monolithic optical waveguide filter comprises a chain of optical couplers of different effective lengths linked by differential delays of different lengths. The transfer of the chain of couplers and delays is the sum of contributions from all possible optical paths, each contribution forming a term in a Fourier series whose sum forms the optical output. A desired frequency response is obtained by optimizing the lengths of the couplers and the delay paths so that the Fourier series best approximates the desired response. The filter is advantageously optimized so that it is insensitive to uncontrolled fabrication errors and is short in length. The wavelength dependence of practical waveguide properties is advantageously incorporated in the optimization. Consequently, the filter is highly manufacturable by mass production. Such filters have been shown to meet the requirements for separating the 1.3 and 1.551 .mu.m telecommunications channels and for flattening the gain of Er amplifiers.

Monolithic optical waveguide filters based on Fourier expansion

The invention relates to a fixed gap waveguide taper. The waveguide taper has a first end and a second end for being coupled to a fiber. The waveguide taper includes a plurality of segments extending from the first end toward the second end. The segments include a gap portion and a core portion. In the present invention, the gap portion remains fixed at a constant length s throughout the entire waveguide taper. In contrast, the core section of the segment varies from the waveguide end of the taper toward the fiber end of the taper. In particular, the core section in each of the segments progressively decreases in length from the waveguide end toward the fiber end of the taper. Accordingly, the length of the segment .LAMBDA. progressively decreases from the waveguide end toward the fiber end of the taper.

Two-dimensional segmentation mode tapering for integrated optic

A waveguide Bragg reflector is made by forming periodic grooves in either the undercladding or the core, applying a high index coating on the grooved surface and selectively removing the coating from the horizontal surfaces while leaving the coating on the vertical surfaces. The waveguide is then completed.

Method for making Bragg reflectors for waveguides

A new electro-optic sampling probe with femtosecond resolution suitable for ultra-fast electro-optic sampling. The new probe is several times thinner and has a dielectric constant four times less than the best reported conventional bulk LiTaO.sub.3 probes. In addition, the ultimate bandwidth is 50 percent greater than an equivalent LiTaO.sub.3 probe. The probe is a thin film of Al.sub.x Ga.sub.1-x As used in both total internally reflecting and free-standing geometries. Here x is chosen for sufficient transmission of the crystal to the wavelength of the laser source being used for electro-optic sampling. The thickness of the film is a small fraction of the thickness of prior art probes and is chosen, for speed and sensitivity of electro-optic sampling, to be thin compared to the spatial extent of the laser pulse. The thin film probe eliminates many of the problems associated with the use of bulk crystals as electro-optic sensors.

Al.sub.x Ga.sub.1-x as probe for use in electro-optic sampling

A solution of H.sub.2 O.sub.2 and EDTA selectively etches GaAs-containing Group III-V compounds in the presence of other Group III-V compounds. Illustratively, Al.sub.y Ga.sub.1-y As (y.ltoreq.0) is selectively etched in the presence of Al.sub.x Ga.sub.1-x As(x&gt;y), and InGaAs is selectively etched in the presence of either InAlAs or InP.

Selective etch for GaAs-containing group III-V compounds

An etching process is described for etching aluminum containing III-V semiconductor compounds. The etch solution contains dichromate ion in acid aqueous solution in which the acid is either phosphoric acid or sulfuric acid. The etch solution is highly selective in that it etches the aluminum containing III-V semiconductor compounds without etching significantly other III-V semiconductor compounds not containing aluminum exposed to the same etching solution. the etching process is extremely useful in fabricating a variety of III-V semiconductor devices including heterojunction bipolar transistors, heterojunction field effect transistors and self-enhanced electro optic devices.

Selective etching process

A photoelectrochemical etching process is described for n-type and semi-insulating III-V semiconductor compounds that contain aluminum or indium (AlGaAs, InGaAs) in which a non-aqueous electrolyte is used. High etch rates are achieved without harm to exposed metallization or p-layers. An exemplatory application is the separation of chips (e.g., LED chips) after wafer processing.

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Scotch Plains, NJ, United States of America

Edward J Laskowski