L.M.F. Chirovsky

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>>

Symmetric self-electrooptic effect device: optical set-reset latch, differential logic gate, and differential modulator/detector

The symmetric self-electrooptic-effect device (S-SEED), a structure consisting of two p-i-n diodes electrically connected in series and acting as an optically bistable set-reset latch, is discussed. Applications and extensions of this device are also discussed. The devices do not require the critical biasing that is common to most optically bistable devices and thus is more useful for system applications. They have been optically cascaded in a photonic ring counter and have been used to perform different NOR, OR, NAND, and AND logic functions. Using the same device, a differential modulator that generates a set of complementary output beams with a single voltage control lead and a differential detector that gives an output voltage dependent on the ratio of the two optical input powers have been demonstrated. >

Symmetric self‐electro‐optic effect device: Optical set‐reset latch

We demonstrate an integrated symmetric self‐electro‐optic effect device consisting of two quantum well p‐i‐n diodes electrically connected in series. The device acts as a bistable optical memory element with individual set (S) and reset (R) inputs and complementary outputs (optical S‐R latch). The switching point is determined by the ratio of the two inputs, making the device insensitive to optical power supply fluctuations when both power beams are derived from the same source. The device also shows time‐sequential gain, in that the state can be set using low‐power beams and read out with subsequent high‐power beams. The device showed bistability for voltages greater than 3 V, incident optical switching energy densities of ∼16 fJ/μm2, and was tested to a switching time of 40 ns.

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.

Batch fabrication and operation of GaAs-Al/sub x/Ga/sub 1-x/As field-effect transistor-self-electrooptic effect device (FET-SEED) smart pixel arrays

The structure, processing, and performance of arrays of integrated field-effect transistor-self-electrooptic effects devices (FET-SEEDs) consisting of doped-channel field-effect transistors, multiple quantum-well (MQW) modulators, and p-i-n MQW detectors are discussed. The performance of the FETs and SEEDs such as g/sub m/ and contrast, is equivalent to that obtained when they are made separately. Typical values are g/sub m/=80 mS/mm and contrast of 3. The largest arrays contain 128 circuits. The circuits operate at speeds as fast as 500 Mb/s, with optical input switching energy of approximately=400 fJ. At 170 Mb/s, the required optical input switching energy is approximately=70 fJ. This optical energy is at least a factor of 20 less than for symmetric SEEDs (S-SEEDs) with the same optical window sizes. Hence, FET-SEEDs provide superior performance compared to conventional S-SEEDs. >

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>>

Optical receivers for optoelectronic VLSI

We describe our work on the design and testing of optical receivers for use in optoelectronic VLSI. The local nature of the optoelectronic VLSI system permits novel receiver designs, incorporating multiple optical beams and/or synchronous operation, while the requirement of realizing large numbers of receivers on a single chip severely constrains area and power consumption. We describe four different receiver designs, and their different operating modes. Results include 1-Gb/s high-impedance, two-beam diode-clamped FET-SEED receivers, single and dual-beam transimpedance receivers realized with a hybrid attachment of multiple-quantum well devices to 0.8-/spl mu/m linewidth CMOS operating to 1 Gb/s, and synchronous sense-amplifier-based optical receivers with low (/spl sim/1 mW) power consumption. Finally, we introduce a measure of receiver performance that includes area and power consumption.

Progress in planarized vertical-cavity surface-emitting laser devices and arrays

We report batch-processed, totally planar, vertical-cavity top surface emitting GaAs/AlGaAs laser devices and arrays. Different size devices are studied experimentally. We measure continuous-wave threshold currents down to 1.7 mA and output powers > 3.7 mW at room temperature. We also discuss interesting characteristics such as differential quantum efficiencies exceeding unity and multi-transverse mode behavior. An array having 64 X 1 individually-accessed elements is characterized and shown to have uniform room-temperature continuous-wave operating characteristics in threshold current approximately equals 2.1 +/- 0.1 mA, wavelength approximately equals 849.4 +/- 0.8 nm, and output power approximately equals 0.5 +/- 0.1 mW.

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.