L.A. D'Asaro

GaAs MQW modulators integrated with silicon CMOS

We demonstrate integration of GaAs-AlGaAs multiple quantum well modulators to silicon CMOS circuitry via flip-chip solder-bonding followed by substrate removal. We obtain 95% device yield for 32/spl times/32 arrays of devices with 15 micron solder pads. We show operation of a simple circuit composed of a modulator and a CMOS transistor.<<ETX>>

Vertical-cavity surface-emitting lasers flip-chip bonded to gigabit-per-second CMOS circuits

We describe the first integration of vertical-cavity surface-emitting laser arrays with gigabit-per-second CMOS circuits via flip-chip bonding.

A 2 kbit array of symmetric self-electrooptic effect devices

A 64*32 array of symmetric self-electrooptic effect devices, each of which can be operated as a memory element or logic gate, is discussed. The required optical switching energies of the devices were approximately 800 fJ and approximately 2.5 pJ at 6 and 15 V bias, respectively, and the fastest switching time measured was approximately 1 ns. Either state of the devices could be held with continuous or pulsed incident optical signals with an average optical incident power per input beam of approximately 200 nW or less than 1 mW for the entire array. Photocurrent and reflectivity were measured for all 2048 devices. Only one device failed to have the negative resistance required for bistability, and only nine of the devices fell outside a band of +or-20% of the mean. Additionally, over 200 devices in the array were operated in parallel using low-power semiconductor laser diodes.<<ETX>>

1-Gb/s two-beam transimpedance smart-pixel optical receivers made from hybrid GaAs MQW modulators bonded to 0.8 μm silicon CMOS

We have made two-beam smart-pixel optical receivers using a hybrid attachment of GaAs-AlGaAs multiple quantum-well (MQW) pin devices to foundry-fabricated 0.8-/spl mu/m linewidth CMOS circuits. Results from a repeater in which receiver output is coupled to a transmitter circuit driving a differential pair of MQW modulators are reported. When tested with high-contrast, directly-modulated laser diodes, an optical energy of 26 fJ (-21.5 dBm) in each beam is required to obtain a bit error rate of 1/spl times/10/sup -9/ at 622 Mb/s, and operation at this error rate is observed to 1 Gb/s. The described receiver (one of several we have made) has three amplification stages, with the first being of the transimpedance type. The reported receiver fits easily within a 45/spl times/25 /spl mu/m area, and the entire repeater circuit draws about 2 mA from a 5-V power supply, with the transmitter accounting for about 20 percent of the total.

16 x 16 VCSEL array flip-chip bonded to CMOS VLSI circuit

We report the flip-chip bonding of a 16/spl times/16 array of 970-nm vertical-cavity surface-emitting lasers (VCSELs) to an array of silicon CMOS driver circuits. The small-signal bandwidth of a flip-chip bonded VCSEL is in excess of 4 GHz. Individual VCSELs are capable of being modulated by the CMOS circuits at 1 Gb/s. The thermal impedance of the flip-chip bonded VCSELs is 1/spl deg/C/mW. The measured crosstalk suppression between channels is approximately 20 dB. Simultaneous parallel testing of up to 80 VCSELs at 1 Gb/s per VCSEL is demonstrated.

Module for optical logic circuits using symmetric self-electrooptic effect devices

An optical module designed to perform cascadable optical logic using arrays of symmetric self-electrooptic effect devices (S-SEEDs) is described. The operation of an array of 7 x 3 devices with optical windows spaced by 20 microm is demonstrated including both array preset and individual device switching. The issues leading to the design of this optical system are detailed. This work illustrates some of the issues which must be considered when designing systems using small reflecting electrooptic devices such as SEEDs and free-space optics in digital systems.

Operation of a fully integrated GaAs-Al/sub x/Ga/sub 1-x/As FET-SEED: a basic optically addressed integrated circuit

The authors experimentally demonstrate the operation of a fully integrated optoelectronic circuit with optical input and output consisting of a p-i-n photodetector and load resistor, a depletion-mode GaAs-Al/sub x/Ga/sub 1-x/As heterostructure field-effect transistor (HFET) and self-biased HFET load, together with an output GaAs-Al/sub x/Ga/sub 1-x/As multiple quantum-well optical modulator. All elements have been monolithically integrated within a 50- mu m*50- mu m area. A low optical power input causes a modulation of a higher-power output, demonstrating optical signal amplification.<<ETX>>

High-speed optoelectronic VLSI switching chip with >4000 optical I/O based on flip-chip bonding of MQW modulators and detectors to silicon CMOS

We present the first high-speed optoelectronic very large scale integrated circuit (VLSI) switching chip using III-V optical modulators and detectors flip-chip bonded to silicon CMOS. The circuit, which consists of an array of 16/spl times/1 switching nodes, has 4096 optical detectors and 256 optical modulators and over 140K transistors. All but two of the 4352 multiple-quantum-well diodes generate photocurrent in response to light. Switching nodes have been tested at data rates above 400 Mb/s per channel, the delay variation across the chip is less than /spl plusmn/400 ps, and crosstalk from neighboring nodes is more than 45 dB below the desired signal. This circuit demonstrates the ability of this hybrid device technology to provide large numbers of high-speed optical I/O with complex electrical circuitry.

Energy scaling and subnanosecond switching of symmetric self-electrooptic effect devices

The authors report the scaling of switching energy with device area for four sizes of symmetric self-electrooptic effect devices, the smallest of which has a switching energy of 3.6 pJ. Switching speeds of approximately 2 ns at 15 V bias and approximately 860 ps at 22 V bias were attained by using mode-locked (6 ps) pulses, although the energies in these pulses were somewhat higher, because of saturation of the quantum-well material. Making the device area only moderately larger than the spot size is suggested as a method of avoiding this saturation.<<ETX>>

Optical digital processor using arrays of symmetric self-electrooptic effect devices

Four arrays of thirty-two GaAs symmetric self-electrooptic effect devices were optically interconnected to form a looped-pipeline optical digital processor. Several circuits were demonstrated, including two shift registers and a decoder circuit. Clock frequencies of up to 1 MHz were attained. Possible extensions to and limitations of this system are described.