Optical waveguides – With optical coupler – Particular coupling structure
Reexamination Certificate
2005-01-11
2005-01-11
Lee, John D. (Department: 2874)
Optical waveguides
With optical coupler
Particular coupling structure
C385S016000
Reexamination Certificate
active
06842569
ABSTRACT:
Optical switches based on the balanced bridge interferometer design require precisely made (or half a coupling length) directional couplers to achieve minimum crosstalk for the two switch outputs. Precision 3 dB-directional couplers require the waveguide dimensions and fabrication parameters of the evanescent region to be tightly controlled making a low crosstalk switch difficult to manufacture and expensive. A new type of balanced bridge interferometer type switch is disclosed where the input and output directional couplers are asymmetrically biased to induce a certain difference in the propagation constants between the two waveguide in the directional couplers. By using the asymmetrically biased directional couplers with a certain tuning a bias voltage for the directional couplers. Low crosstalk switches can be achieved for a very wide range of directional coupler strengths, relaxing the precise half-coupling length directional couplers required in conventional design. This relaxation of the precise directional coupler waveguide regions allows a relaxation in the manufacturing tolerance of the devices and therefore make the switch much easier to make. Because low crosstalk switches can be a device with an extended operating range and broader directional coupler parameters, switches can be used for a much broader wavelength bandwidth. In one of the embodiments, this new design allows a device to switch both TE and TM mode optical signals simultaneously at low crosstalk levels to result in a polarization-independent optical switch.
REFERENCES:
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patent: 4679893 (1987-07-01), Ramer
patent: 4763974 (1988-08-01), Thaniyavarn
patent: 5202941 (1993-04-01), Granestrand
patent: 5375180 (1994-12-01), Murphy
Eospace, Inc.
Fleshner & Kim LLP
Lee John D.
Stahl Mike
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