Abstract: An optical receiver, e.g., receiver 10 (FIG. 1), has differential optical input beams and generates an electrical output. The voltage at an electrical node between series-connected optical detector diodes is clamped within a predefined voltage range by series-connected clamping diodes, to prevent the voltage from increasing when consecutive logic one optical input beams are received. Variable bandwidth and low energy dissipation are achieved since the resistors of high input impedance and transimpedance receivers are not required. A second optical receiver, e.g., receiver 20 (FIG. 2) is a monolithic, diode-clamped S-SEED with complementary optical input beams and complementary optical output beams.

Abstract: A multi-stage network which achieves the same overall connectivity as known networks but where individual switching nodes have no input selectivity and no output selectivity. Each node is enabled or disabled to control communication therethrough in response to a single control signal. The functionality of a switching network is achieved by controlling which nodes are enabled rather than specifying connections of particular node inputs and outputs to be effected by the nodes. In a photonic network embodiment, each network node is implemented using a single symmetric self electro-optic effect device (S-SEED).

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: A network comprising a plurality of successively interconnected node stages where each node has an associated data connection state and includes a control element, significantly implemented as part of the node itself, for controlling the data connection state of at least one node of the following stage. The network is well suited for optical implementation and is controlled by shifting bits into the network for storage by the control elements rather than relying on spatial light modulators.

Abstract: A network arrangement and control method where, before any transmission of data occurs for a particular communication, a network controller determines an unused path to provide a connection, advantageously all the way through the network from a given inlet to a given outlet. Once the identity of the unused path is known, the controller determines control information for use in activating that path and transmits that control information into the network, significantly via the network inlets. The network responds by activating the determined path and communication is enabled via the activated path, but only for the single connection and no buffering of information is required within the network. The network is particularly well suited for optical implementation and control is effected without the use of spatial light modulators but rather by means of control elements embedded within the network itself.

Abstract: A multi-stage network which achieves the same overall connectivity as known networks but where individual switching nodes have no input selectivity and no output selectivity. Each node is enabled or disabled to control communication therethrough in response to a single control signal. The functionality of a switching network is achieved by controlling which nodes are enabled rather than specifying connections of particular node inputs and outputs to be effected by the nodes. In a photonic network embodiment, each network node is implemented using a single symmetric self electro-optic effect device (S-SEED).

Abstract: An optoelectronic apparatus where information is communicated to and from the apparatus in the optical domain, but where the apparatus includes a transmission gate advantageously interposed between successive optoelectronic gates to sequentially convey information internally in the form of electrical, rather than optical, signals. Illustratively, the transmission gate is optoelectronic and comprises two back to back p-i-n photodiodes each including a quantum well region. The first and second optoelectronic gates are S-SEEDs comprising p-i-n photodiodes also each including a quantum well region. The transmission gate is responsive to a first level of the optical control signal for substantially blocking current, and to a second level of the optical control signal for substantially passing current. Applications of the apparatus include its use in a shift register, 2.times.1 switch, 1.times.2 switch, and an exclusive OR gate.

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: 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: 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.

Abstract: Apparatus comprising a monolithic structure having an array of substructures, e.g., mesas, each including first and second photodetectors electrically connected as components of different self electro-optic effect devices. The devices are optically interconnected due to the positioning of the component photodetectors within a single mesa.

Abstract: An optically bistable device, such as a symmetric self electro-optic effect device (S-SEED), is forced into a metastable state prior to the incidence of an optical input signal thereto, thereby increasing the sensitivity of the optically bistable device to the optical input signal, reducing both the switching time and the optical input signal energy required to switch the device. The metastable state is entered into by one of three techniques: (1) turning off the bias voltage V.sub.0 of the device with optical bias beams on then turning on the bias voltage V.sub.0 with the optical bias beams off; (2) applying a predetermined voltage to a node in the device, the predetermined voltage being substantially the metastable state voltage or V.sub.0 /2; or (3) subjecting the device to equal intensity optical bias beams having a wavelength longer than the exciton wavelength.

Abstract: A tri-state optical device 400 is disclosed having photodiodes 401 and 402 with respective quantum-wells 403 and 404 in the intrinsic regions. The photodiodes are connected in series with a bipolar switch 406 and a source of electrical potential 405 for emitting a pair of optical output beams having various combinations of power levels depending on the state of the bipolar switch and the ratio of two optical control beams incident on the photodiodes. In one state of the tri-state device with the bipolar switch in a conducting state, the two output beams have complementary high and low power levels representing, for example, high and low logic levels "1" and "0". In a second state, the power levels of the two output beams are reversed, thus exhibiting complementary and symmetric output power levels.

Abstract: An optically bistable device 100 is disclosed having first and second semiconductor multiple quantum well regions 101 and 102 with complementary high and low absorption levels for emitting first and second output light beams 162 and 163 having complementary low and high power levels. The optical device comprises first and second photodetectors 103 and 104 having respective quantum well regions 101 and 102. The photodetectors are responsive to first and second light beams 160 and 161 for electrically controlling the optical absorption of each of the two quantum well regions. The state of the device is determined by the transmission level of light beam 161 passing through multiple quantum well region 102 and being emitted as output light beam 162, whereas the complementary state of the device is determined by the transmission level of complementary output light beam 162.

Abstract: An optically bistable device 100 is disclosed having a self electro-optic effect device (SEED) 104 and a variable optical attenuator 103 for maintaining the state of the SEED over a wide power range of two input light beams. The SEED is responsive to the relative power levels of the two input light beams for assuming one of two states. The state of the SEED is determined by the transmission level of one of the beams passing through quantum well region 102 of the device. The variable optical attenuator concomitantly varies the power level of the two input beams to maintain the present state of the SEED over a wide range of input light beam powers. When operated in a bistable operating region of the device, a control light beam with a low power level changes the device from one state to another. Two threshold values of a ratio of power between the two input beams establish where the device switches from one state to the other.