Abstract: An optoelectronic detector includes multilayered semiconductor structures that are placed at particular positions in a standing wave pattern in order to measure the intensity of the light beams passing through said structures' layers. The detector is made sensitive to particular wavelengths by either changing the light beams intensity or varying the absorbance of the layers.

Abstract: An apparatus for amplifying the optical power ratio includes first and second input electro-absorption modulators coupled together in series that each receive an optical input beam. First and second output electro-absorption modulators are coupled together in series and each generate an optical output beam. A voltage amplifier electrically couples a first node located between the first and second input modulators to a second node located between the first and second output modulators. In operation, the power ratio of the output beams is a function of the power ratio of the input beams.

Abstract: A drive circuit for increasing the voltage range applied across optical modulators in a transmitter stage of an optical communication system. The circuit comprises a first switch and a second switch connected thereto. The first switch is responsive to a first input signal and has a maximum voltage drop equal to a first reference voltage. The second switch is responsive to a second input signal and has a maximum voltage drop equal to a second reference voltage. A modulator is connected between the first and second switches so that, depending on the values of the first and second input signals, the maximum voltage drop across the modulator will be a value greater than either the first or the second reference voltage.

Abstract: An optical amplifier includes a photodetector such as a photodiode for receiving an optical input signal to be amplified. An electro-absorption modulator is responsive to a photocurrent generated by the photodetector such that the modulator absorbs a portion of an optical beam transmitted therethrough in an amount proportional to an amplified replica of the photocurrent. The remaining portion of the beam transmitted through the modulator forms a signal that is an inverted, amplified replica of the input signal.

Abstract: An optical receiver apparatus and method for receiving optical signals and for generating output signals is disclosed. In particular, a photoconductor is illuminated with a preset beam before an input beam is incident on a detector to reset an input FET. An optical receiver according to the invention controls the voltage swings and the allowed voltages at the input stage, and can be monolithically integrated to allow uniform operation across a semiconductor chip and between circuits on different chips.

Abstract: Apparatus and methods of near-field scanning optical microscopy (NSOM) are described. A sensing technique is used, in which a light source having an optical cavity is reflectively coupled to the sample surface. Changes in the surface properties of the sample at the sensed location alter the optical feedback in the light source. This leads to detectable changes in the output characteristics of the light source.

Abstract: Arrays of light beams are combined in a manner that minimizes optical power loss by passing a first array of light beams through an angle-variant device onto a target surface while reflecting a second array of light beams off the angle-variant device onto the target surface. The light beams of the first array are arranged to strike the angle-variant device at a first family of angles at which the angle-variant device is substantially transmissive. The light beams of the second array are arranged to strike the angle-variant device at a second family of angles at which the angle-variant device is substantially reflective.

Abstract: Enhanced optical information processing capability is achieved by providing a self-electrooptic effect device (SEED) which modulates one or more power supply beams to provide integer gain in an input optical signal. This "integer gain" SEED includes a predetermined number of quantum well diodes electrically connected in series with a current supply so that, at steady state, each quantum well diode conducts the same current and thus absorbs the same amount of optical power. An optical input signal is replicated by configuring the quantum well diodes such that each quantum well diode receives its own power supply beam. The optical input signal is amplified by configuring the quantum well diodes such that a single power supply beam passes through all of the quantum well diodes.

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.

Abstract: Saturation intensity and loss of a saturable absorber are substantially independently regulated by positioning the saturable absorber element within a Fabry-Perot etalon defined by first and second reflective elements so that the saturable absorber element responds to light at optical wavelengths in the anti-resonant portion of the Fabry-Perot spectral response, that is, between optical wavelengths corresponding to resonance peaks. The resulting combination of elements is called a Fabry-Perot saturable absorber. Thickness of the saturable absorber element substantially sets the loss of the Fabry-Perot saturable absorber while changes in the reflectivity of the first reflective element onto which the light is incident substantially determines the saturation intensity (degree of nonlinearity) and assists in compensating loss of the saturable absorber element.

Abstract: Monolithic optically bistable modulator arrays, such as an M.times.N array of S-SEEDs, are electrically addressed with a matrix of electrical row and column contacts. Connected to the center node of each S-SEED is an addressing means having elements, such as diodes, transistors, or capacitors, which are electrically enabled and disabled.

Abstract: Apparatus for combining information beams by using a space variant mirror in the context of free space optical switching and computing, where light beams comprise beamlets that are focused onto surfaces to form arrays of light spots. Beam combining is achieved by positioning the space variant mirror to coincide with the plane on which the spots are focused, and to thereby allow one beam to pass through the space variant mirror without loss and another beam to be reflected off the space variant mirror, also without loss.

Abstract: An apparatus comprises a support and a tower pivotally attached to the support and movable relative to said support between a raised and a lowered position. The tower is rotatable to and from a predetermined position about a longitudinal axis thereof when the tower is the raised position. A latch device is displaceable between a secured position and a non-secured position, the tower being prevented from moving to the lowered position when the tower is raised and the latch device is in the secured position. A release system prevents displacement of the latch device from the secured position when the tower is not in the predetermined and raised positions. The release system permits displacement of the latch device from the secured position when the tower is in the predetermined and raised positions. The latch device includes a plunger and a biasing member located within a latch housing. The release system includes a contact element which is connected to the plunger.

Abstract: A reduced-blocking system where a perfect shuffle equivalent network having a plurality of node stages successively interconnected by link stages, is advantageously combined with expansion before the node stages and/or concentration after the node stages in a manner allowing the design of a system with arbitrarily low or zero blocking probability. An illustrative photonic system implementation uses free-space optical apparatus to effect a low loss, crossover interconnection of two-dimensional arrays of switching nodes comprising, for example, symmetric self electro-optic effect devices (S-SEEDs). Several low loss beam conbination techniques are used to direct multiple arrays of beams to an S-SEED array, and to redirect a reflected output beam array to a subsequent node stage.

Abstract: Resonant tunneling devices having an improved device switching speed are realized by including an optical control element rather than an electrical control element for switching the device from one stable state to the other. The resulting optoelectronic device including at least one double barrier quantum well semiconductor heterostructure is controllably switched from an active state to an inactive state and vice versa by impinging optical signals from an optical control element having a mean photon energy less than the bandgap energy of the double barrier quantum well semiconductor heterostructure, wherein the active state of the device exhibits conduction of charge carriers by resonant tunneling. Improvement in the switching speed occurs because the optical processes initiated by the optical control element are condsiderably faster than the electronic processes induced by prior art electrical control elements.

Abstract: Optical apparatus for performing wavelength-dependent beam combination. The apparatus relies on a polarization beam splitter in combination with other optical elements to develop combined beams with the same polarization type and that are therefore suitable for polarization-dependent combination with other beam arrays. A dichroic mirror, which is used as the wavelength-dependent element of the apparatus, is oriented such that the incident beams are substantially perpendicular to the mirror. With this orientation, the dichroic mirror achieves near-ideal performance even with beam arrays having a substantial angular field. The apparatus also uses two plates which, although designed for operation as quarter-wave plates at one of the two wavelights being combined, are oriented with their respective fast axes substantially perpendicular to each other such that polarization conversions, effected by the plates on beams having the other of the two wavelengths, substantially cancel each other.

Abstract: Boolean logic functions are provided in a programmable optical logic device by combining a symmetric self-electrooptic effect device (S-SEED) with a logic control element for optically programming the S-SEED to initiate logic operations from a predetermined state. The predetermined preset state together with subsequent application of optical data signals to the S-SEED permit the desired logic operation to be performed on the optical data signal by the optical logic device. Logic operations which may be programmed into the optical logic device include AND, NAND, OR and NOR functions. A complementary pair (Q and Q) of optical signals is provided as output from each optical logic device.

Abstract: An electrooptic measuring apparatus having both high voltage sensitivity and femtosecond time resolution includes coplanar transmission lines fabricated on a semi-insulating multiple quantum well structure. An electrical signal, such as from a high speed electronic device, injected onto the transmission lines creates an electrical field parallel to the layer planes of the multiple quantum well structure. Excitonic electroabsorption by the multiple quantum well structure, in response to the parallel field, changes the transmissivity of the multiple quantum well structure. An external light beam directed through the multiple quantum well structure is modulated by the changes in transmissivity. By detecting this modulation, a sampling of the electrical signal is achieved.

Abstract: Apparatus having a plurality of photodetectors interconnected to form an electrical circuit corresponding to any given logic function comprising at least two of the four basic AND, OR, NAND, and NOR logic operations. The apparatus performs optical logic without optical cascading since the electrical circuit controls the generation of an optical output beam based on the value that the given logic function assumes in response to a plurality of optical signal beams each incident on at least one of the photodetectors. A complementary optical output is obtained and time-sequential operation is effected when two, serially connected quantum well p-i-n diodes comprising an S-SEED are used to generate optical output beams in response to the voltage developed by the electrical circuit of interconnected photodetectors.

Abstract: Apparatus having a first electrical circuit, comprising a plurality of photodetectors interconnected such that the first circuit corresponds to any given logic function, is connected in series with a second circuit comprising a plurality of photodetectors interconnected as the conduction complement of the connections of the first circuit. The apparatus performs optical logic without optical cascading since the first and second circuits control the generation of an optical output beam based on the value that the given logic function assumes in response to a plurality of optical signal beams incident on the photodetectors of the first circuit and a plurality of complementary beams incident on the photodetectors of the second circuit. A complementary optical output is obtained and time-sequential operation is effected when two, serially connected quantum well pin diodes comprising an S-SEED are used to generate optical output beams in response to the voltage developed by the first circuit.