smart pixel arrays.pptx
TRANSCRIPT
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SMART PIXEL ARRAYSSPAsSHIVA MOHAMMADZADEH
JAN. 2015
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DEFINITION OF “SMART PIXEL”
• Integration of photo detector arrays and processing electronic logic circuits on a single semiconductor substrate
• Capable of performing parallel processing of large pixelated images by reducing a complex image into a manageable stream of signals
• Establish optical connections between input and output devices for many channels in parallel
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SMART PIXEL ARRAY
• A two dimensional array of optoelectronic devices
• Relates optical input and output with electrical process
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WHY SMART PIXEL ARRAYS?
• Suitable for board to board interconnections in digital systems
• The high space–bandwidth product (SBP) of optics
• Crucial to meet the demanding performance needs in high-speed switching ; optical interconnects in computers, and flat-panel display applications
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APPLICATIONS OF SPAs
• In the field of image processing, data processing, digital signal processing
• Many applications requiring high performance image capturing use SPAs, which integrate very special functionality at the pixel level
• The 3D image sensors consisting of SPAs are used to evaluate size, shape and volume in industrial automation applications
• SPAs are also used for optical data interconnect and optical memory access.
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PERFORMANCE
• The complexity of the logic operation in a pixel defines the smartness of that pixel
• Increasing the functionality of a pixel increases the area needed for the electronics
• “Granularity”, another criterion of smartness
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COMPONENTS
• Optical decoder
• Processing elements
• I/O Pins
• VCSEL Drivers
• Photodetector Array
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HOW DOES IT WORK?
• Multiple-quantum-well (MQW) modulators or vertical-cavity surface-emitting lasers (VCSELs) as the optical source
• Two approaches, monolithic and hybrid (e.g., monolithic VCSELs/GaAs and hybrid VCSELs/Si)
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WHY VCSEL?
• Because of the ability to form two dimensional arrays
• They are constructed out of material that is convenient for fabrication of photodetectors and logic circuits.
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VCSEL
• Substrate
• Layers of GaAs and AlAs the Bragg planes
• Quantum well region gain occurs
• p and n doped regions p-n diode junction
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ADVANTAGES
• High data-transmission rates through high-speed switching
• Decreased cross-talk, by virtually eliminating interference phenomenon
• Interconnects are lighter compared to today’s copper wires
• Provide high processing speeds by consuming significantly less optical power
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DISADVANTAGES
• Potential problems in combination of electronics and optoelectronics
• Fabrication of efficient light sources in silicon-based systems not mature enough
• GaAs based systems in electronic logic circuits are lagging behind silicon based CMOS technology
• The low efficiency of photodetectors results in reduced switching speed thus decreasing the data transfer rate
• Expensive
• Non-uniformity may result due to fabrication imperfections
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POSSIBLE APPROACHES TO SMART PIXEL FABRICATION
• Development of detectors and emitters based on indirect band-gap materials such as Si and Ge
• Epitaxial growth of GaAs or similar III-V semiconductor material on Si
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FUTURE
• To achieve more compact packaging leads to smaller components, shortens electrical connections within the SPA leading to higher potential speeds.
• To scale the SPAs to larger array dimensions.
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THANK YOU