Optical switching apparatus and method
First Claim
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1. An apparatus for controlling the transmission of a light signal of a selected wavelength therethrough, the apparatus comprising:
- an active semiconductor region having a temperature-dependent band gap energy, the band gap energy of the active semiconductor region at a first temperature value being greater than the photon energy of the selected wavelength, and at a second temperature value being equal to or lesser than the photon energy of the selected wavelength;
means for receiving a light signal of the selected wavelength into at least a portion of the active semiconductor region; and
means for controlling the temperature of the active semiconductor region, the temperature controlling means including means for receiving a control signal to heat the active semiconductor region, whereby;
in the absence of the control signal the temperature of the active semiconductor region is caused to be at the first temperature value and a portion of the light signal received by the active semiconductor region is emitted from the active semiconductor region, andreceiving the control signal the temperature of the active semiconductor region is caused to switch to the second temperature value for at least as long as the control signal is received to decrease the portion of the light signal emitted from the active semiconductor region.
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Abstract
An apparatus and method for switching unpolarized light are provided. The apparatus includes GaInAs/GaAs optical switching devices which can be fabricated using conventional processes on a single wafer in matrix arrangement to provide an n×m cross bar switch. Switching is accomplished by shifting the band gap of the GaInAs material of a device using electrical or optical power to heat the material. Each switching device may comprise two-polarity (n/p) or single polarity (n or p) semiconductor materials.
15 Citations
23 Claims
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1. An apparatus for controlling the transmission of a light signal of a selected wavelength therethrough, the apparatus comprising:
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an active semiconductor region having a temperature-dependent band gap energy, the band gap energy of the active semiconductor region at a first temperature value being greater than the photon energy of the selected wavelength, and at a second temperature value being equal to or lesser than the photon energy of the selected wavelength; means for receiving a light signal of the selected wavelength into at least a portion of the active semiconductor region; and means for controlling the temperature of the active semiconductor region, the temperature controlling means including means for receiving a control signal to heat the active semiconductor region, whereby; in the absence of the control signal the temperature of the active semiconductor region is caused to be at the first temperature value and a portion of the light signal received by the active semiconductor region is emitted from the active semiconductor region, and receiving the control signal the temperature of the active semiconductor region is caused to switch to the second temperature value for at least as long as the control signal is received to decrease the portion of the light signal emitted from the active semiconductor region. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A semiconductor device for switching a light signal of a selected wavelength, comprising:
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a semiconductor substrate; an active switching region of semiconductor material formed on the substrate and having a band gap edge at room temperature at a wavelength shorter than the selected wavelength; a layer of semiconductor material formed between the active region and the substrate to accommodate lattice mismatch; a surface formed on the active switching region for receiving the light signal; and means for receiving a control signal to selectively raise the temperature-of the active switching region above room temperature so as to cause the band gap edge of the active semiconductor region to switch to a wavelength longer than the selected wavelength, whereby the device is switched from an on state to an off state. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. An optical cross bar switch comprising:
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a substrate of semiconductor material; switching means including a plurality of individual thermally activated switching devices for selectively switching light signals, the devices being formed in a parallel matrix on the substrate and each device comprising an active semiconductor switching region in which switching is activated by applying a control signal to the device to change the temperature of the active semiconductor switching region, whereby the thermally activated switching of a light signal can be controlled without requiring variation of a property of the light signal to activate switching; and a light receiving surface formed on each switching device. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method for switching a light signal of a selected wavelength, comprising the steps of:
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transmitting the light signal into a switching medium having a thermally sensitive coefficent of optical absorption at the selected wavelength; disposing the switching medium such that at least a portion of the light signal transmitted into the switching medium exits the switching medium and is received by a light receiving device; and controlling the temperature of the switching medium by selectively applying a second signal to the switching medium, the application of the second signal to the switching medium causing an increase in the temperature of at least a portion of the medium into which the light signal is transmitted whereby the second signal causes the switching medium to switch from an on state to an off state and the portion of the light signal exiting the switching medium is decreased.
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23. A method for switching a light signal of a selected wavelength, comprising the steps of:
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transmitting the light signal into a switching medium having a thermally sensitive coefficent of optical absorption at the selected wavelength; disposing the switching medium such that at least a portion of the light signal transmitted into the switching medium exits the switching medium and is received by a light receiving device; and controlling the temperature of the switching medium by selectively applying a second signal to the switching medium, the application of the second signal to the switching medium causing an increase in the temperature of at least a portion of the medium into which the light signal is transmitted whereby the second signal causes the switching medium to switch from an off state to an on state and the portion of the light signal exiting the switching medium is increased.
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Specification