At&t Bell Laboratories

Renen Adar

Charles H Henry

Rudolf F Kazarinov

Corrado Pietro Dragone

Victor Mizrahi

Linn F Mollenauer

Michele A Milbrodt

Rodney C Kistler

Paul A Morton

An optical pulse source includes a semiconductor diode laser, an external optical cavity, and a source of a modulated drive current such that the laser can be actively mode-locked. The external cavity includes an optical fiber and a distributed Bragg reflector. In preferred embodiments, the optical pulse source can produce pulses having a time-bandwidth product within about 20% of the transform limit, such that soliton pulses can be transmitted.

Compact optical pulse source

In optical apparatus for reading, writing or erasing optical disks, the optical head is implemented in integrated form. Silicon optical bench technology, including integrated optical waveguides, Y-splitters and directional couplers, is used in the design of the tracking, lens focussing, and read/write/erase functions.

Tracking and focussing functions in optical disk apparatus

In accordance with the invention an integrated optic device useful as a low level polarization independent optical tap comprises a pair of optical waveguides intersecting at an angle of 10.degree.-25.degree. to provide a tap signal in the range minus 20 dB to minus 60 dB. In a preferred embodiment for use in a passive repeater for undersea cable, the device comprises fiber-matching waveguides of phosphorus silicate glass on an oxide covered silicon substrate with a boron and phosphorus silicate cladding. The waveguides preferably intersect at an angle of 13.degree.-16.degree.. The preferred repeater further comprises a 3 dB coupler for averaging the power provided by two external pumping sources and a pair of wavelength division multiplexers for applying the pumping power to the outputs of the tap.

Polarization independent optical tap

An integrated optic device useful as a planar lens or a low order array multiplexer comprises a pair of optical couplers and an array of plural waveguides extending between the couplers in an 'S' configuration to provide closely spaced optical path lengths. An 'S' configuration provides equal path lengths for an optical lens. Incremental lengths added to the 'S' in the region between curve reversal can provide small path length increments for a low order array multiplexer or demultiplexer.

Planar lens and low order array multiplexer

Disclosed are planar waveguides comprising substantially polarization-independent Bragg gratings. A preferred embodiment of the invention comprises a Si body with a silica lower cladding layer thereon, and a phosphorus P-doped silica core on the lower cladding. Appropriate periodic recessed features are etched into the core, and phophorus P- and B-doped silica upper cladding is deposited over the core. The dopant concentrations are adjusted such that the refractive index difference between core and upper cladding is small (0.35-1.45.times.10.sup.-2), and such that the flow temperature of the upper cladding material is lower than that of the core material. In another preferred embodiment a thin layer of Si.sub.3 N.sub.x (x.about.4) is conformally deposited over the core after the grating etch, and the upper cladding material is deposited onto the Si.sub.3 N.sub.x layer. Bragg devices according to the invention are advantageously used in Integrated Optical Circuits (IOCs), e.g. in IOCs used in WDM optical communication systems.

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Westfield, NJ, United States of America

Renen Adar