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US 6,108,111 AGranted
Ferroelectric optical computing device with low optical power non-destructive read-out
AssigneeCalifornia Institute of Technology
InventorsSarita Thakoor, Anilkumar P. Thakoor
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Abstract
Photoresponse from a ferroelectric optical computing device, such as a memory cell or a logic switch, is increased by either illuminating the regions of the ferroelectric crystal under the electrode edges in a sandwich structure device or by aligning the principal axis of the ferroelectric crystal parallel to the linear polarization vector of the optical beam. Device density is increased by reducing the beam size using a small near-field optical fiber. Device evaluation including imprint failure susceptibility is performed by illuminating each ferroelectric optical computing device in a large array of such devices and storing the device address of any device whose response departs from a normal range.
Claims12
An optical computing device responsive to an optical beam having a beam diameter, said optical computing device comprising:
- a bottom electrode having a planar surface;
- a ferroelectric crystalline thin film layer overlying said planar surface of said bottom electrode, said ferroelectric crystalline thin film layer having two stable polarization states and a principal crystalline axis and being responsive to an electric field having a component along said principal axis by transitioning between said polarization states, said principal axis being generally non-parallel to said planar surface of said bottom electrode;
- and
- a top electrode facing a direction of arrival of said optical beam and having a planar surface generally parallel to said bottom electrode overlying said ferroelectric crystalline thin film layer and having a width not exceeding said beam diameter of said optical beam, wherein said width defines first and second peripheral regions on said ferroelectric crystalline thin film layer which bounds the entire width of said top electrode, wherein said first and second peripheral regions of said ferroelectric crystalline thin film layer underlying said top electrode are illuminated by said optical beam;
- wherein said peripheral regions are coupled to an optical polarization vector of said optical beam oriented perpendicular to said principal axis to create deviated secondary crystalline axes within said ferroelectric crystalline thin film layer, said deviated secondary crystalline axes being generally non-parallel to said principal axis and located at opposite ends of said ferroelectric crystalline thin film layer to bound said principal axis.
2 more elements
An optical computing hybrid integrated circuit, comprising:
- a photoresponsive layer comprising plural rows and columns of photoresponsive cells each responsive to a respective optical beam having a beam diameter, said photoresponsive layer comprising:
- a bottom electrode having a planar surface;
- a ferroelectric crystalline thin film layer overlying said planar surface of said bottom electrode, said ferroelectric crystalline thin film layer having two stable polarization states and a principal crystalline axis and being responsive to an electric field having a component along said principal axis by transitioning between said polarization states, said principal axis being generally non-parallel to said planar surface of said bottom electrode;
- a top electrode facing a direction of arrival of said optical beam and having a planar surface generally parallel to said bottom electrode overlying said ferroelectric crystalline thin film layer and having a width not exceeding said beam diameter of said optical beam, wherein said width defines first and second peripheral regions on said ferroelectric crystalline thin film layer which bounds the entire width of said top electrode, wherein said first and second peripheral regions of said ferroelectric crystalline thin film layer underlying said top electrode are illuminated by said optical beam;
- wherein said peripheral regions are coupled to an optical polarization vector of said optical beam oriented perpendicular to said principal axis to create deviated secondary crystalline axes within said ferroelectric crystalline thin film layer, said deviated secondary crystalline axes being generally non-parallel to said principal axis and located at opposite ends of said ferroelectric crystalline thin film layer to bound said principal axis;
- row and column address conductors connected to respective ones of said top and bottom electrodes of said photoresponsive layer;
- and
- an optical beam source layer overlying said photoresponsive layer and comprising rows and columns of beam source cells facing respective ones of said photoresponsive cells and row and column address conductors connected to respective ones of said beam source cells.
5 more elements
A two-cell optical computing device having a bipolar response to an optical beam having a beam diameter, said optical computing device comprising:
- a bottom electrode having a planar surface;
- a ferroelectric crystalline thin film layer overlying said planar surface of said bottom electrode, said ferroelectric crystalline thin film layer having two stable polarization states and a principal crystalline axis and being responsive to an electric field having a component along said principal axis by transitioning between said polarization states, said principal axis being generally non-parallel to said planar surface of said bottom electrode;
- and
- first and second top electrodes facing a direction of arrival of said optical beam and having planar surfaces generally parallel to said bottom electrode overlying said ferroelectric crystalline thin film layer and together spanning a width not exceeding said beam diameter of said optical beam, wherein said width defines first and second peripheral regions on said ferroelectric crystalline thin film layer which bounds the entire width spanned by said top electrodes, wherein said first and second peripheral regions of said ferroelectric crystalline thin film layer underlying said top electrodes are illuminated by said optical beam, and said first and second top electrodes constituting the terminals of said device;
- wherein said peripheral regions are coupled to an optical polarization vector of said optical beam oriented perpendicular to said principal axis to create deviated secondary crystalline axes within said ferroelectric crystalline thin film layer, said deviated secondary crystalline axes being generally non-parallel to said principal axis and located at opposite ends of said ferroelectric crystalline thin film layer to bound said principal axis.
2 more elements
Dependencies are inferred from the claim text.