Here are some parts that I found interesting in the patent Thyristor-Based Optical XOR Circuit (yes I know... got nothing to do tonight).

POET Building Blocks

The electronic circuit components (such as the HFET transistors and electrical thyristors) as well as the optoelectronic circuit components (such as the optical hybrid couplers and optical thyristors) of the circuits as described herein can be implemented in one or more integrated circuits based on technology (referred to by the Applicant as “Planar Optoelectronic Technology” or “POET”). POET provides for the realization of a variety of devices (optoelectronic devices, logic circuits and/or signal processing circuits) utilizing inversion quantum-well channel device structures as described in detail in U.S. Pat. ...

With these structures, a fabrication sequence can be used to make the devices on a common substrate. In other words, n type and p type contacts, critical etches, etc. can be used to realize all of these devices simultaneously on a common substrate. The essential features of this device structure include 1) an n-type modulation doped quantum well interface and a p-type modulation doped quantum well interface, 2) self-aligned n-type and p-type channel contacts formed by ion implantation, 3) n-type metal contacts to the n-type ion implants and the bottom n-type layer structure, and 4) p-type metal contacts to the p-type ion implants and the top p-type layer structure. The active device structures can be realized with group III-V materials. Such group III-V materials can include gallium (Ga) and arsenic (As) (for gallium arsenide layer structures) as well as aluminum (Al) and indium (In), and thus can include GaAs, AlGaAs, and InGaAs semiconductor alloys. Alternatively, such group III-V materials can include gallium (Ga) and nitrogen (N) (for gallium nitride layer structures) as well as aluminum (Al) and indium (In), and thus can include GaN, AlGaN, and InGaN semiconductor alloys.

POET can be used to construct a variety of optoelectronic devices. POET can also be used to construct a variety of high performance transistor devices, such as complementary n-channel and p-channel HFET unipolar transistor devices as well as n-type and p-type HBT bipolar transistor devices.

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The n-channel and p-channel HFET phototransistors have advantages over a simple diode detector. More specifically, a diode detector produces photocurrent characterized by low current (high resistance) and high capacitance. Therefore, a transimpedance amplifier is necessary to amplify the output of the diode detector in order to increase the bandwidth. However, the n-channel and p-channel HFET phototransistors have an internal transconductance (gm=dV/dI) and hence produces voltage output directly without the need for a transimpedance amplifier.

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Thyristor-Based Optoelectronic Oscillator

For configuration as an optoelectronic oscillator, the thyristor closed-path waveguide resonator 2101 can be configured for digital optical-to-electrical conversion where the optical signal propagating in the waveguide 2102 generates photocurrent by absorption which adds electrons to the n-type modulation doped QW structure 1715 and holes to the p-type modulation doped QW structure 1711 such that the thyristor device switches ON and conducts current through the device between the anode terminal electrode and the cathode terminal electrode. Such optoelectronic operations provide the function of detection, current-to-voltage conversion (typically provided by a transimpedance amplifier), level shifting to obtain a ground reference and a decision circuit (typically realized by a comparator). Moreover, the thyristor closed-path waveguide resonator 2101 has an advantage that it will only absorb at the resonator frequency and thus can be adapted to support different wavelengths for wavelength division multiplexing applications. Moreover, the ON state current that flows between the anode terminal electrode and the cathode terminal electrode of the thyristor resonator is configured above the threshold for lasing ITH, such that photon emission will occur within the device structure. ...