U.S. Philips Corporation

Other

Raymond Van Roijen

Engelbertus C Pennings

Lukas Frederik Tiemeijer

Coen T Liedenbaum

John J Reid

Bastiaan H Verbeek

Patrick H Van Gestel

Petrus Ja Thijs

The invention relates to an optical unit (17) for synchronizing clock signals. The unit (17) comprises at least two ring lasers (1', 1'), each ring laser (1', 1') generating a repetitive optical pattern at a different repetition frequency f.sub.i. The repetition frequency of at least one of the ring lasers (1', 1') is variable. The unit (17) comprises detection means (19) adapted to simultaneously receive the optical patterns from two ring lasers (1', 1') to be synchronized with each other and to compare these patterns. The ring laser, whose repetition frequency is variable, is controllable on the basis of a signal from the detection means, by which the optical path length of this laser is changed. The invention also relates to a high-frequency carrier transmission system comprising an optical unit as described hereinbefore.

Optical unit for synchronizing clock signals

An optical unit for multiplying the frequency of a clock signal includes at least two series-arranged ring lasers. Each ring laser has a different resonance frequency f.sub.i. The unit has an input for receiving a signal, for example, a low-frequency electric signal for modulating one of the ring lasers. The repetition frequency of at least one of the ring lasers is variable by adapting the optical path length of the resonator.

Optical unit for multiplying the frequency of a clock signal

A passive region is provided adjacent the mirror surface of a laser. A mesa is formed with an end face parallel to the mirror surface to be formed. The passive region is grown against the end face, and the mirror surface is formed therein by cleaving. The passive region is provided exclusively at the area of the active region. The passive region is provided at the area of the active region preferably in the following manner: two depressions are formed in the layer structure of the laser at the area of the mirror surface to be formed, reaching down to the active layer. Then a portion of the active layer situated between the depressions is selectively removed, whereupon the passive region is grown starting from the depressions in the tubular cavity thus formed.

Method of manufacturing an optoelectronic semiconductor device, in

Multimode imaging component and ring laser provided with a multimode

A ring laser is described, which has a ring (1) in which laser radiation is generated. A coupler (4) couples a part of the radiation in the form of two waves (7,8) to two waveguides (5,6). A combiner (11) combines the two waves to an output wave (12) in an output waveguide (13). By providing a reflector (16) in the output waveguide, a part of the output wave is reflected to the ring via the combiner, the two waveguides and the coupler. The radiation waves travelling in the ring couple to the reflected wave and thereby acquire a well-defined phase difference. The resultant phase equality of the two waves (7,8) at the input of the combiner ensures that the powers of the waves are added in phase so that the ring laser supplies the maximum possible power.

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Yorktown Heights, NY, United States of America

Raymond Van Roijen