Photonic page buffer based on GaAs multiple-quantum-well modulators bonded directly over active silicon complementary-metal-oxide-semiconductor (CMOS) circuits

We present a 2-kbit, 50-Mpage/s, photonic first-in, first-out page buffer based on gallium arsenide/aluminium-gallium arsenide multiple-quantum-well diodes that are flip-chip bonded to submicrometer silicon complementary-metal-oxide-semiconductor circuits. This photonic chip provides nonvolatile storage (buffering), asynchronous-to-synchronous conversion, bandwidth smoothing, tolerance to jitter or skew, spatial format conversion, wavelength conversion, and independent flow control for the input and the output channels. It serves as an interface chip for parallel-accessed optical bit-plane data. It represents the first smart-pixel array that accomplishes the vertical integration of multiple-quantum-well modulators and detectors directly over active silicon VLSI circuits and provides over 340 transistors per optical input-output. Results from high-speed single-channel testing and real-time array operation of the photonic page buffer are reported.     

Energy scaling and subnanosecond switching of symmetricself-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 ~2 ns at 15 V bias and ~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     

High speed 2×4 array of differential quantum well modulators

The 3-dB bandwidth of the modulators was measured to greater than 3 GHz, and the time response was measured to 200 ps. By using short mode-locked pulses, the 3-dB bandwidth of the devices used as differential detectors was measured to be greater than 4 GHz and the risetime to be ~100 ps     

Ring oscillators with monolithically integrated-optical readoutbased on GaAs-AlGaAs FET-SEED technology

Ring oscillators having integrated-optical readout are realized in GaAs-AlGaAs field-effect transistor self-electro-optic-effect-device (FET-SEED) technology-a monolithic integration technology for FET's and normal-incidence multiple-quantum-well modulators and detectors. Good agreement between simulated and measured DC-inverter-transfer characteristics is shown. At one bias point, ring oscillator frequencies correspond to unity fan-in and fan-out delay values of 129.5 ps/stage. The power-delay product at this bias point was 306 fj. Measurements were made on circuits whose transistors had a transconductance of about 80 mS/mm. Simulations of inverter delay are discussed, including load capacitances, and are found to be in good agreement with experiment     

Field effect transistor-self electrooptic effect device (FET-SEED)differential transimpedance amplifiers for two-dimensional optical datalinks

A 4×18 two-dimensional array of GaAs FET-SEED (field effect transistor-self electrooptic effect device) differential transimpedence receivers has been fabricated for application in massively parallel optical data link board-to-board interconnections. Several FET-SEED receiver arrays were tested and displayed a mean response of ~0.7 mV/μW, and were capable of >100 Mbps per channel operation. The mean receiver sensitivity for a BER of <10^-9 was calculated from the measured noise spectrum to be -26.8 dBm at the system design rate of 40 Mbps (18 k-22 MHz bandwidth), and -23.2 dBm for a 100 Mbps rate (dc-66 MHz bandwidth). A sensitivity of approximately -25 dBm for the 40 Mbps rate was confirmed using a bit-error-rate test set. The theoretical noise is compared to measured values with good agreement assuming a FET channel noise factor of 1.4. The 1/f noise corner frequency of ~13 MHz was found to cause a ~1.2 dB degradation in sensitivity for the 100 Mbps rate. The differential amplifier mean dc output offset voltage was measured to be 10 mV, and displayed a large sigma due to parameter variations in the active devices. Two receiver arrays were successfully used in a demonstration of a fully differential parallel optical small computer system interface (SCSI) data link     

Batch fabrication and structure of integrated GaAs-AlxGa1-xAs field-effect transistor-self-electro-optic effectdevices (FET-SEED's)

The authors have demonstrated a smart pixel prototype field-effect-transistor-self-electrooptic-effect-device (FET-SEED) integrated optoelectronic amplifier utilizing process technology suitable for flexible design and fabrication of high-yield optoelectronic circuits. A single MBE growth sequence provides for quantum-well modulators, photodiodes, doped channel MIS-like field-effect transistors (DMTs), and resistors. The device dimensions are controlled in a planar technology using ion implantation and selective plasma etching for isolation and contacting. Results demonstrate optical amplification in a fully integrated circuit. This technology will enable increased functionality by providing digital electronic processing between optical input and output     

Logic self-electrooptic effect devices: quantum-well optoelectronicmultiport logic gates, multiplexers, demultiplexers, and shift registers

Two-dimensional arrays of logic self-electrooptic effect devices (L-SEEDs), consisting of electrically connected quantum-well p-i-n diode detectors and modulators are demonstrated. The topology of the electrical connections between the detectors is equivalent to the connections between transistors in CMOS circuits. Three different L-SEED arrays were built and tested. Each element in one array can implement any of the four basic Boolean logic functions (i.e., NOR, NAND, AND, OR). Each element in the second L-SEED array can implement the function E=AB+CD. The third L-SEED array consists of 32×16 arrays of symmetric SEEDs (S-SEEDs) connected with optoelectronic transmission gates. Photonic switching nodes, multiplexers, demultiplexers, and shift registers have been demonstrated using this array     

Ring oscillators with optical and electrical readout based onhybrid GaAs MQW modulators bonded to 0.8 μm silicon VLSIcircuits

Loaded and unloaded ring-oscillator circuits with an electrical and surface-normal 850 nm optical readout are fabricated using a hybrid 0.8 μm silicon-CMOS/GaAs-AlGaAs MQW process. Measurements of the oscillation frequency of these circuits show total capacitance associated with the flip-chip-bonded optical MQW modulators as low as 52 fF     

Multidimensional characterization of piezoresistive carbon black silicone rubber composites

Flexible and stretchable electronic skins capable of replicating the human sense of touch are a subject of active research. One of the most popular materials for force sensors in skins is carbon black (CB)/polydimethylsiloxane composite. To aid in skin design, a characterization of this composite is presented here. The sensitivity of composite resistance to uniaxial tension, compression, and shear for each CB concentration is measured and found to be similar for tension and compression, but smaller for shear, with resistance monotonically increasing with strain. In addition, under tension and compression the resistance of the material is measured both in line with and perpendicular to the axis of applied strain, and the response is found to be approximately equal in both cases. The electrical and mechanical relaxation time of the material is also measured and modeled for tension, compression, and shear. The mechanical relaxation time is found to be shorter than the electrical, with both increasing with CB concentration. However, the shortest mechanical relaxation time, 200 s, precludes a sensor with human‐like response times without an active modeling and compensation system. Finally, Young's modulus and Poisson's ratio are measured and reported for each CB concentration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44773.     

High-speed optoelectronic VLSI switching chip with >4000 opticalI/O based on flip-chip bonding of MQW modulators and detectors tosilicon 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 16×1 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 ±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