Lucent Technologies Inc.

At&t Bell Laboratories

Bell Telephone Laboratories

Other

At+t Corp.

Agere Systems Guardian Corp.

American Telephone and Telegraph, Co.

American Telephone & Telegraph Co., At&t Bell Laboratories

At&t Ipm Corp.

Bell Laboratories, Inc.

Corrado Pietro Dragone

Christopher Richard Doerr

Michael J Gans

Ivan P Kaminow

Herman M Presby

Alastair M Glass

Pietro Arturo Bernasconi

Jerry Chia-yung Chen

Thomas Andrew Strasser

Mark E Kuznetsov

Joseph Earl Ford

Charles H Henry

Yuan P Li

Anthony Acampora

Lawrence Warren Stulz

Benjamin Irvin Greene

Ta-Shing Chu

Renen Adar

Cynthia A Volkert

Ralph A Semplak

A planar optical router consisting of two stages performing stationary imaging has advantages of reduced size, increased number of channels and reduced crosstalk. In one embodiment, each stage of the router includes a waveguide grating, and the router produces several sets of interleaved images, with the property that different sets are characterized by different diffraction orders of the two gratings. The new arrangement substantially increases the number of output waveguides, as compared to previous arrangements using only one set of images, characterized by the same order of the output stage. Moreover, since adjacent sets are characterized by different orders, crosstalk is substantially reduced. In a second embodiment, the number of output waveguides is further increased by including two gratings in the second stage.

Optical router with stationary response and increased number of channels

An optimized planar optical router consisting of two stages performing stationary imaging between an input waveguide and a set of output waveguides has advantages of reduced size, larger number of channels and minimal loss variation in each passband. The new router is an optimized M&#xd7;N imaging arrangement including two waveguide gratings and n waveguide lenses connected between the principal zones of the two gratings. The largest values of N are realized by using a combination of two techniques that increase N without increasing the size of the two gratings. One technique increases N for a given number n of lenses and, the other, increases n. In one embodiment, each lens produces a periodic sequence of passbands, all transmitted from a particular input waveguide to the same output waveguide, whereas, in a second embodiment, the above passbands are transmitted to different output waveguides. In both cases, the loss caused by secondary images is substantially reduced by including secondary lenses.

Optical router with nearly ideal performance and increased number of channels

An optimized planar optical router consisting of two stages performing stationary imaging between an input waveguide and a set of output waveguides has advantages of reduced size, larger number of channels and minimal loss variation in each passband. Each stage is a waveguide grating router, the two stages are characterized by nearly equal free-spectral ranges, and a waveguide lens is connected between the two stages. In one embodiment, the lens is connected between the central zones of the two stages, and the diffraction orders of the two stages vary monotonically from each passband to the next. In another embodiment, the loss caused by secondary images is substantially reduced by using a composite lens providing efficient transmission of both principal and secondary images.

Optical router with nearly ideal performance

A planar optical device useful as a low order wavelength router is realized by using a waveguide grating comprising two curved arrays of opposite curvatures. The diffraction order is determined by the angles of rotation of the two curved arrays, and any nonzero order less than about 30 can be realized. This arrangement is smaller, and performs better than a previous grating using a combination of three curved arrays.

Waveguide grating optical router suitable for CWDM

A planar optical filter consisting of two stages performing stationary imaging between an input waveguide and a set of output waveguides is characterized by reduced crosstalk and minimal loss variation in each passband. The input stage is a small waveguide grating router, connected to the output stage by a waveguide lens essentially covering the entire central zone of the input router. In one embodiment, the second stage includes two waveguide grating routers and the lens has two separate output apertures, respectively connected to these two routers. In this arrangement, 2N input channels applied to the input port are separated by the first grating into two interleaved sets of N channels each. The two sets are respectively transferred by the composite waveguide lens to the two output gratings which respectively separate the N channels of each set. In another embodiment, the output router only includes one output grating, and several stationary images are produced, at the same waveguide location, by different orders of the output grating.

Optical router using stationary imaging

An optical interconnection apparatus including waveguide arrays such as waveguide lenses, waveguide gratings and star couplers, has improved efficiency realized using a periodic array combined with an arrangement of matching sections. The array is connected to a slab region containing the array focal point and the purpose of the matching sections is to minimize unwanted radiation by the array outside the central zone of the array. This unwanted radiation is primarily caused by two particular unwanted modes excited at the array junction with the slab, and the resulting loss is minimized by properly choosing the average phase shift applied by each section to said unwanted modes.

Efficient waveguide arrays with optimized matching transitions

Apparatus for filtering an optical input signal includes a coupler and an arrayed waveguide grating connected to the coupler having a phase shifting region. The phase shifting region is a back wall of a free space region of the arrayed waveguide grating with concentric image and reflector surfaces. Radial waveguides between the surfaces are divided into alternating regions of wider and thinner sets of waveguides. A corresponding change in optical length alters the phase of the input signal which forces an output signal of a desired wavelength to appear at a desired port of the filter.

Apparatus for filtering optical signals

An optical interconnection apparatus including waveguide arrays such as waveguide lenses, waveguide gratings and star couplers, has improved efficiency realized by using a periodic array including in each period a combination of two radial waveguides. The array is formed with angular period &#x3b1; between an input circle and an output circle and it includes an input section, connected to the input circle, and an output section connected to the output circle. The input section includes a single waveguide in each period and it is efficiently coupled with minimal loss to the output section, whose waveguides are approximately arranged with period &#x3b1;/2 in the final region close to the output circle.

Efficient waveguide arrays with nearly perfect element patterns

An N&#xd7;N crossconnect switch is implemented without the use of waveguide crossings. In one embodiment, the N&#xd7;N crossconnect switch uses two non-parallel planar arrays of 1&#xd7;2 and 2&#xd7;1 switching elements combined with a cylindrical reflector. In another embodiment, the N&#xd7;N crossconnect switch includes an input planar array and output planar array implemented on a single wafer both having a refractive index n&#x3e;1 separated by a central region having a refractive index n=1.

N&#xd7;N switching arrangement of two planar arrays without waveguide crossings

A switching apparatus provides 1&times;2 and 2&times;2 switching functions having significantly reduced crosstalk levels using an imaging arrangement of three arms combined with two star couplers. In another 1&times;2 switching element embodiment, the input star coupler is replaced with an optical signal splitter. Application of the 1&times;2 and 2&times;2 switching elements include the realization of a variety of dilated N&times;N broadband switches with negligible crosstalk over very wide wavelength stopband characterized by two or more equally spaced zeros. The very wide crosstalk stopband enables the N&times;N broadband switch to switch a broadband wavelength division multiplexed input signal to the desired output port with very low crosstalk at the other output ports.

Broadband optical switching arrangements with very low crosstalk

An optical imaging arrangement includes a wavelength router having ( ) N waveguides connected to different locations of the input curved boundary of the router, ( ) a grating that forms multiple paths through the router and which transforms a particular wavelength applied to one of the N waveguides into N interleaved sets of equally spaced output images corresponding to the different orders of the grating ( ) an output curve illuminated by the various images and ( ) N interleaved sets of reflective elements placed along the output curve with properly chosen periodicity, such that all significant orders of each set of images are reflected back through the arrangement, so as to effectively produce a single input reflection in only one of the N waveguides of the arrangement, and the particular waveguide is determined by the phase shifts produced by the sets of reflective elements.

Waveguide grating arrangement using a segmented reflector

An integrated 1&times;K wavelength-selective cross connect (WSC) comprises a demultiplexer arranged to couple each of the N individual wavelength in an input optical WDM signal to a different one of N demultiplexer outputs. Each of N planar beam steerers, arranged along the left edge of a free space region, receives and directs a different one of the N light beams from the demultiplexer to a location on the right edge of the free space region. Each of K gratings arranged along a different location on the right edge of the free space region multiplexes together any light beam received at that location. The 1&times;K WSC can be implemented with or without the use of crossovers.

Integrated wavelength-selective cross connect

A filtering system for eliminating dispersion caused by filtering an optical signal with a birefringent filter. Dispersion is eliminated by causing each signal to be passed twice through a birefringent filter. Dispersion created by the first pass is canceled out by dispersion created in the second pass. The same filter may be used for both passes with a polarization rotation applied between the two passes. Specifically, the first pass produces dispersion defined by transmission coefficients C and D. Because of the polarization rotation, the second pass creates dispersion defined by the complex conjugates of transmission coefficients C and D, which cancel out dispersion caused by the first pass. Mathematically, each transmission coefficient of the first pass is multiplied by its complex conjugate of the second pass, and the resulting transmission coefficients &verbar;C&verbar; , &verbar;D&verbar; are entirely free of dispersion caused by the filter. A method for filtering an optical signal using a birefringent filter to eliminate dispersion is also provided.

Filtering system for eliminating dispersion and method for doing same

A wavelength slicer uses a waveguide grating router having a periodic arrangement of reflectors in the output circular boundary of the router, which causes each input signal to pass twice through the router. The slicer includes two interleaved sets of equally spaced reflectors. Each set is slightly displaced from the output curve, and their displacements are properly chosen so as to effectively produce a phase shift of &pgr;/2 between the reflected signals. The reflected signals again pass through the router to produce two separate signals, containing respectively the even and odd channels of the input signal. A second slicer embodiment is realized using two gratings that are coupled to elliptical and circular reflectors. A wavelength filter is realized by forming on the output curve a set of equally spaced reflectors with spacing equal to an integer fraction of the spacing of the images.

A programmable broadband N&times;N cross-connect switch includes an N&times;N wavelength coupler combined with N tunable lasers, N modulators and N optical receivers. Each of the N tunable lasers can selectively produce N different wavelengths. The coupler couples the N wavelengths to the N modulators. The N modulators modulate the N wavelengths using N input electrical signals, each modulator being selectable by choosing a laser wavelength. The N optical receivers receive and detect the N modulated wavelengths to produce N output electrical signals therefrom, each receiver receiving and detecting a different one of the N different wavelengths. By selecting a laser wavelength a particular modulator and receiver is selected so that a modulated signal, formed at the selected modulator when an input electrical signal modulates the selected wavelength, is switched to the selected receiver.

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Little Silver, NJ, United States of America

Corrado Pietro Dragone