Gec-marconi Limited

Marconi Communications Gmbh

Marconi UK Intellectual Property Limited

Marconi Lck Intellectual Property, Ltd.

Rosemary Cush

William James Stewart

Ruth Hibberson

Andrew Carter

An optical add-drop filter for use in a communication system which is capable of communicating both supervisory traffic and communication traffic. Communication traffic is modulated onto first radiation occupying a first range of radiation wavelengths, and supervisory traffic is modulated onto second radiation occupying a second range of radiation wavelengths. When the first and second radiation is received at one or more of the nodes, it is then filtered in the add-drop filters associated therewith to isolate add channels, drop channels, a supervisory channel drop and a supervisory add from primary relatively-low attenuation paths of the filters. The add channels, the drop channels, and the supervisory channel drop and add are then isolated at secondary paths associated with, but not included in the primary paths.

Optical add-drop filter

The present invention provides a wavelength selective optical filter device ( ) for receiving input radiation and outputting corresponding filtered output radiation, characterized in that the filter device ( ) includes a plurality of at least partially mutually coupled Fabry-Perot optical resonators ( ) for filtering the input radiation to generate the output radiation, the filter device ( ) being tunable from a first radiation wavelength to a second radiation wavelength by mutually detuning the resonators in a period where the resonators are being retuned from the first wavelength (&lgr; ) to the second wavelength (&lgr; ) so that the filter device ( ) is substantially in a non-responsive state during the period. The resonators incorporate freely suspended mirrors ( ) which are electrostatically actuated to affect tuning of the resonators ( ). The filter device ( ) is thereby capable of tuning between different wavelengths without tuning through wavelengths therebetween. The filter device ( ) can be included into an add-drop filter ( ) for providing channel add and drop functions when the filter ( ) is incorporated in a multichannel WDM communication system ( ).

Wavelength selective optical filter

The present invention provides a wavelength selective optical filter device ( ) for receiving input radiation and outputting corresponding filtered output radiation, characterised in that the filter device ( ) includes a plurality of at least partially mutually coupled Fabry-Perot optical resonators ( ) for filtering the input radiation to generate the output radiation, the filter device ( ) being tunable from a first radiation wavelength to a second radiation wavelength by mutually detuning the resonators in a period where the resonators are being returned from the first wavelength (&lgr; ) to the second wavelength (&lgr; ) so that the filter device ( ) is substantially in a non-responsive state during the period. The resonators incorporate freely suspended mirrors ( ) which are electrostatically actuated to affect tuning of the resonators ( ). The filter device ( ) is thereby capable of tuning between different wavelengths without tuning through wavelengths therebetween. The filter device ( ) can be included into an add-drop filter ( ) for providing channel add and drop functions when the filter ( ) is incorporated in a multichannel WDM communication system ( ).

This invention relates to an optical sensor for testing a biochemical sample. The sensor includes a resonant mirror device 1 and a prism 2 disposed adjacent the device 1 for coupling an input beam of light to the device 1. The input beam of light having a comb spectrum with a uniform spacing between adjacent lines or bands of the spectrum is produced by a comb spectrum source 10. The comb spectrum may be produced by a diode laser with multiple longitudinal modes. The input beam of light is polarized by a polarizer 4 to provide equal TE and TM components. The resonant mirror device is arranged in the paths of said input beam of light such that resonance is excited for at least one of said components, An analyser 11 is arranged to receive said components of the beam of light reflected from the device 1 for producing an output beam having a spectrum including a series of bright and/or dark lines or bands corresponding to the lines or bands of the comb spectrum of the input beam. When a sensing layer of the resonant mirror device is sensitized by the chemical sample, an angular shift in the resonance angle takes place and this causes the lines or bands of the output spectrum to be swept across a reference point where detector means 12 is located to count the number of lines or bands swept across the reference point. The angular shift in the resonance angle is equal to the product of the distance between adjacent lines of the comb spectrum and the number of lines swept across the reference point.

Optical sensor

This invention describes a technique for improving the sensitivity of a resonant mirror sensor which has particular applications in areas involving sensing at an interface such as immunosensing using immobilized antibodies. By the introduction of a Bragg grating structure in the sensor, there is produced enhanced dispersion and hence enhanced sensitivity in the region close to the band edge. This improves the detection limit of the sensor without changing the composition or involving the sensor size and allows more sensitive operation at reduced incident angles.

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Northampton, United Kingdom

Rosemary Cush