Differential self-electrooptic effect device
AssigneeAT&T Bell Laboratories
InventorDavid A. B. Miller
Life of this patent
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Abstract
Optical analog information processing capability is achieved by providing a SEED device configured to operate in a differential mode. This "differential SEED" utilizes pairs of input signal beams to represent bipolar analog data and to process those data in a linear fashion. The difference in the optical powers of the input signal beams is used to modulate the absorption of power supply beams in quantum well diodes, such that the difference in the absorbed powers in the quantum well diodes is proportional to the difference in the powers of the input signal beams. The differential SEED can be configured to perform various image processing operations on bipolar analog data, including, for example, image addition and subtraction, optical multiplication, and evaluating spatial derivatives.
Claims18
Semiconductor apparatus comprising:
- first and second quantum well diodes electrically coupled to each other, the first and second quantum well diodes each having an optical input for receiving first and second light beams, respectively, the first and second quantum well diodes absorbing optical energy from the first and second light beams in an amount proportional to an electrical current flowing through the respective quantum well diode;
- and
- means for inducing differential electrical currents within the first and second quantum well diodes.
Semiconductor apparatus for multiplying a signal by a positive or a negative number represented by first and second control beams, the apparatus comprising:
- first and second quantum well diodes coupled electrically in series, each quantum well diode having an optical input for receiving at least one input light beam representing the signal and a different one of the first and second control beams, each quantum well diode absorbing optical energy from a different one of the first and second control beams in an amount proportional to an electrical current flowing through the respective quantum well diode, each quantum well diode having an optical output for outputting at least one output light beam, the output beams representing the product of the signal with the positive or negative number;
- and
- a current source coupled in series with the first and second quantum well diodes.
A method for processing information, the method comprising the step of:
- representing the information as an electrical current of a predetermined magnitude;
- and
- controlling the absorption characteristics of a pair of electrically-connected quantum well diodes with the electrical current so as to modulate the optical power of a pair of light beams having similar optical power, the difference between the power absorbed from one of the light beams and the power absorbed from the other of the light beams being proportional to the magnitude of the electrical current.
Apparatus comprising:
- first and second quantum well diodes;
- means for connecting the quantum well diodes to a current source in such a way as to cause a current to flow through each of said quantum well diodes;
- and
- control means for inducing a change in the difference between the levels of the currents in each of the quantum well diodes,
- whereby, when light energy is applied to each of the quantum well diodes, the control means induces a change in the difference between the respective levels of light energy that are absorbed by the quantum well diodes.
Dependencies are inferred from the claim text.