Transmission system for the polarization-insensitive transmission of signals
AssigneeKoninklijke PTT Nederland N.V.
InventorMattijs O. van Deventer
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Abstract
The invention relates to a transmission system for the polarization insensitive transmission of signals over a signal path between a transmitter and a receiver, provided with high-order retarder. The retarder is a combination of a polarization-splitting coupling and a loop-type delaying transmission route. The retarder may be sited at the receiver end, with a suitably chosen angle between one of the principal axes of the retarder and the polarization of a local oscillator incorporated in the receiver. Advantages are reduction in size and number of components in the retarder, reduction in the number of retarders in such a transmission system and an increase of the capacity for integration.
Claims3
Transmission system for the polarization-insensitive transmission of a frequency-modulated binary digital signal having binary states respectively represented by two optical frequencies, the system comprising:
- a transmitter of said frequency-modulated binary digital signal,
- a transmission path for transmitting said signal,
- a receiver for receiving said signal transmitted via said transmission path, said receiver including a local oscillator for generating a local oscillator signal and a coupling device for coupling said frequency-modulated binary digital signal, when received, with said local oscillator signal, and
- a high-order retarder, having two principal axes, for converting at least a part of said frequency-modulated binary digital signal into a frequency- and polarization-modulated signal having polarization switching between two different polarization states which correspond to said two optical frequencies, characterized in that
- said high-order retarder is connected between said transmission path and said coupling device, and in that
- said local oscillator signal has a polarization which is at an angle to one of the principal axes of said high-order retarder which is greater than 0.degree. and less than 180.degree. according to Poincare's, representation.
Dependencies are inferred from the claim text.