X. An

Switching light with light

The basic characteristics of the light amplifying optical switch (LAOS) are explained. The LAOS, as compared to its electronic counterparts, will substantially reduce the interconnect time between components, chips, PC boards, and machines. The use of the LAOS to implement optical logic circuits with multiple input stages that invert and restore the input signal is discussed. Applications to image and signal processing are examined. Future uses are considered.<<ETX>>

Integrated optical NOR gate

A two-input optical NOR gate structure is proposed and demonstrated. The NOR gate is fabricated from a vertically integrated heterojunction phototransistor and light emitting diode InGaAs-InP structure grown by gas source molecular beam epitaxy. Operation up to 500 kHz is demonstrated for devices fabricated with 250- mu m*250- mu m mesas. Analysis indicates that operation at frequencies up to 50-100 MHz is possible for smaller mesa areas. ON/OFF optical contrast ratios as high as 30 were measured.<<ETX>>

Optoelectronic exclusive-OR (XOR) gate

An optoelectronic circuit that implements the exclusive-OR (XOR) logic function is described. The circuit uses two unmatched heterojunction phototransistors and a light amplifying optical switch (LAOS) monolithically integrated on an InGaAs/InP wafer grown by gas-source molecular beam epitaxy. The circuit was operated from DC up to the limit of the probe stand (90 kHz). The ease of operation and high ON/OFF contrast ratio (>50) make this XOR gate ideal for applications that require optical binary comparison or addition.<<ETX>>

High gain InP/InGaAs phototransistor/LED optical amplifier

Analytical and experimental results for a single-stack optical amplifier to be used in optoelectronic integrated circuits are presented. The device consists of a heterojunction phototransistor (HPT) integrated with a double-heterojunction light-emitting diode (LED) and has been named the light-amplifying optical switch (LAOS). Both components of the LAOS were fabricated separately out of InGaAs/InP grown by gas-source molecular beam epitaxy and found to function as expected. The HPT had a high current gain, and the LED had an emission spectrum centered around 1.7 mu m. The first complete LAOS device has been fabricated and tested. The basic design methodology, device operation, and device characteristics are presented.<<ETX>>

Two wavelength optically controlled latch and AND gate

A new optical device which functions either as a gated latch or an AND gate is demonstrated. This device utilizes two different wavelengths of input light and is composed of two heterojunction phototransistors (HPTs) vertically integrated with a light emitting diode. The collector‐base regions of the two HPTs are fabricated from different band‐gap materials and thus, respond to different wavelengths of input light. The device structure was fabricated from InGaAsP/InP epitaxial layers grown by gas source MBE. The gated latch and AND gate are shown to have an on/off contrast ratio of 12 and 6, respectively.

XOR based on an InP/InGaAs light amplifying optical switch (LAOS)

An optoelectronic circuit that implements the XOR logic function is presented. The light amplifying optical switch (LAOS) device is used as a building block to realize the minterms AB~ and BA~ required for the XOR function. These minterm circuits were monolithically integrated on an InP/InGaAs wafer grown by gas source molecular beam epitaxy and tested on a probe stand. The functionality of the minterm circuit is demonstrated. Load line analysis shows that transistors with unmatched gain characteristics can yield high ON/OFF contrast ratio when transistors are integrated with the lower gain transistor driving the parallel combination of a LAOS device and a higher gain transistor.<<ETX>>

Vertically-integrated InGaAsP/InP two-wavelength all-optical latch/AND gate

A novel optoelectronic device which functions either as an optically controlled gated latch or as an optical AND gate is demonstrated. This device utilizes two different wavelengths (2 lambda ) of input light and is composed of two heterojunction phototransistors with different bandgaps vertically integrated with a light emitting diode. The device structure was fabricated from InGaAsP/InP epitaxial layers grown by gas-source molecular-beam epitaxy. The single-mesa structure of the devices is amenable to large-dimensional array fabrication and the 2 lambda approach makes the input alignment to such an array easier.<<ETX>>

InGaAs/InP OEIC's for optical computing

Techniques for optically controlling the latching capabilities of the light amplifying optical switch (LAOS) are described. It is shown that the latching can be controlled by reducing either the voltage or the current of the latching element. The operation and design of functional blocks that implement set/reset flip flops, gated latches, and inverting logic are discussed.<<ETX>>

Monolithic integration of lasers and bipolar transistors by selective area epitaxy

The authors describe the use of selective area epitaxy to prepare monolithically integrated lasers and heterostructure bipolar transistors (HBTs) based on InGaAs(P)/InP. The laser is a capped mesa buried heterostructure structure grown by metal-organic chemical vapor deposition (MOCVD) and optimized for fiber communications. The HBT structures were grown by metal-organic molecular beam epitaxy (MOMBE) on the semi-insulating current confining layers of the lasers. The quality of selectively grown HBTs is illustrated in the Gummel plot and common emitter output characteristics. The DC performance of an integrated structure is illustrated. The laser is driven with the collector current of the HBT. Threshold is achieved at a base current of I/sub B/=360 /spl mu/A. Light output of the laser is linear to at least 10 mW. Preliminary experiments show the bandwidth of the integrated device to be in excess of 3 GHz.<<ETX>>

Highly compact integrated optical set-reset memory pixels for parallel processing arrays

An integrated optoelectronic device with a single-mesa structure, which functions as an optical set-reset memory or an optical inverter, is reported. The device is composed of two heterojunction phototransistors and a light-emitting diode vertically integrated on an InGaAsP/InGaAs/InP wafer grown by gas source molecular beam epitaxy. The set and reset beams are incident on a single optical window on each device and are separated by wavelength. The prototype device has shown a large on/off control ratio (27) with relatively low input optical power levels (tens of microwatts). This device concept is extendable to large integrated arrays which are capable of directly processing spatial light signals.<<ETX>>