Apparatus for converting optical bipolar signals to optical unipolar signals
AssigneeAT&T Corp.
InventorDavid A. B. Miller
Life of this patent
Estimating the term…
Abstract
An apparatus for converting a bipolar optical signal to a unipolar optical signal includes first and second photodetectors electrically coupled in series for receiving the bipolar optical signal. An electro-absorption modulator such as a self-linearized modulator, for example, is electrically coupled to the photodetectors. The modulator serves to transmit therethrough a portion of the power of an optical beam in an amount proportional to the power of the bipolar optical signal to form a transmitted beam. A constant current source is provided for supplying a current that shifts the power of the optical beam transmitted through the modulator by a predetermined amount, thus forming the desired unipolar optical signal.
Claims11
An apparatus for converting a bipolar optical signal to a unipolar optical signal, comprising:
- first and second photodetectors coupled in series for receiving a bipolar optical signal;
- and
- an electro-absorption modulator and a first transistor serially coupled to said modulator, said modulator being responsive to an electrical signal received from said first and second photodetectors for providing a unipolar optical output signal;
- a second transistor electrically coupled to said first transistor such that said first and second transistors form a current mirror.
An apparatus for converting a bipolar optical signal to a unipolar optical signal, comprising:
- first and second photodetectors coupled in series for collectively generating a first photocurrent supplied to a node;
- an electro-absorption modulator coupled to said first and second photodetectors for generating a second photocurrent in response to an optical beam and for supplying said second photocurrent to said node;
- and
- a constant current source for supplying a predetermined current to said node.
An apparatus for converting a bipolar optical signal to a unipolar optical signal, comprising:
- first and second photodetectors coupled in series for collectively generating a first photocurrent supplied to a node;
- an electro-absorption modulator coupled to said first and second photodetectors for generating a second photocurrent in response to an optical beam and for supplying said second photocurrent to said node;
- and
- a constant current source for supplying a predetermined current to said node, wherein said constant current source comprises a current mirror.
An apparatus for converting a plurality of bipolar optical signals to a plurality of unipolar optical signals, comprising:
- a plurality of optical converters, each of said converters including;
- first and second photodetectors coupled in series for collectively generating a first photocurrent supplied to a node;
- an electro-absorption modulator coupled to said photodetectors for generating a second photocurrent in response to an optical beam and for supplying said second photocurrent to said node;
- and
- means for supplying a predetermined current to said node, wherein said current supply means of a plurality of all of said optical converters comprises a constant current source for supplying a substantially identical predetermined current to each of the nodes in each of the plurality of optical converters and wherein said constant current source comprises a plurality of current mirrors.
An apparatus for converting a bipolar optical signal to a unipolar optical signal, comprising:
- first and second photodetectors electrically coupled in series for receiving a bipolar optical signal;
- an electro-absorption modulator electrically coupled to said photodetectors for transmitting therethrough a portion of the power of an optical beam in an amount proportional to the power of the bipolar optical signal to form a transmitted beam;
- and
- means for selectively shifting the power of the transmitted beam by a predetermined amount to form a unipolar optical signal.
Dependencies are inferred from the claim text.