Optical switching with ferroelectric liquid crystal SLMs

An optical switch comprising an input optical fiber array, the input optical fiber array having plural input optical fibers, and an output optical fiber array, and an optical system connecting the input optical fiber array to the output optical fiber array wherein the optical system comprises first to fifth lenses, the first lens being a first bulk lens for receiving light from all of the plural input optical fibers of the input optical fiber array, a first ferroelectric liquid crystal spatial light modulator, and a second ferroelectric liquid crystal spatial light modulator, each spatial light modulator being adapted for providing a respective selectable set of holograms, wherein the first bulk lens is disposed to receive light from all of the plural input optical fibers and to provide a plurality of collimated light beams from said input optical fiber array to be incident upon the first ferroelectric liquid crystal spatial light modulator, said first ferroelectric liquid crystal spatial light modulator providing a corresponding plurality of light beams, a second lens, a third lens and a fourth lens, the said second lens being disposed to receive said corresponding plurality of light beams and to provide a corresponding plurality of mutually convergent beams, the third lens having a negative power, said third lens disposed to receive said convergent beams and to provide plural mutually divergent output beams, and the fourth lens being disposed to receive said plural mutually divergent beams and collimate said plural mutually divergent beams to be incident upon said second liquid crystal spatial light modulator, said second ferroelectric liquid crystal spatial light modulator providing a corresponding plurality of light beams, the fifth lens being disposed for focussing said corresponding plurality of light beams from said second ferroelectric liquid crystal spatial light modulator onto said output optical fiber array.

An optical switch comprising an input optical fiber array, the input optical fiber array having plural input optical fibers, an output optical fiber array, and an optical system connecting the input optical fiber array to the output optical fiber array wherein the optical system comprises a first bulk lens for receiving light from all of said plural input optical fibers of the input optical fiber array, a first ferroelectric liquid crystal spatial light modulator, a second ferroelectric liquid crystal spatial light modulator, each spatial light modulator being adapted for providing a respective selectable set of holograms, an interconnect region between said first and second ferroelectric liquid crystal spatial light modulators, and a second bulk lens providing output light to the output optical fiber array wherein the first bulk lens is disposed to provide a plurality of collimated light beams from said input optical fiber array, said optical switch further comprising a second lens and a fourth lens, the said second lens for receiving said collimated light beams and providing a corresponding plurality of mutually convergent beams, the optical system further comprising a third lens having a positive power, receiving said convergent beams and providing mutually divergent output beams as a unity conjugate lens, and the fourth lens being disposed for receiving said mutually divergent beams and collimating said beams wherein said second bulk lens is a fifth lens being disposed for focussing said beams onto said output optical fiber array.

An optical switch comprising an input optical fiber array and a receiver array, and an optical system connecting the input optical fiber array to the receiver array wherein the optical system comprises a first binary reconfigurable spatial light modulator, a second binary reconfigurable spatial light modulator, each spatial light modulator being adapted for providing a respective selectable set of holograms each for a desired switching operation, and a pair of lenses between said first and second binary reconfigurable spatial light modulators for defining therebetween an interconnect region, wherein each spatial light modulator comprises a display screen, memory circuitry for storing a plurality of sets of hologram data, and selection circuitry for selecting one of said sets according to a desired switching function, each stored set of hologram data being calculated by:

• determining principal replay co-ordinates of a said hologram according to a desired switching function;
• using said co-ordinates, calculating the size in pixels of a base cell;
• evaluating a base cell pattern by a phase-quantization procedure;
• and
• replicating said base cell pattern data until the entire aperture of the spatial light modulator is filled.

An optical switch comprising an input optical fiber array and a receiver array, and an optical system connecting the input optical fiber array to the receiver array wherein the optical system comprises a first ferroelectric liquid crystal spatial light modulator, a second ferroelectric liquid crystal spatial light modulator, each spatial light modulator being adapted for providing a respective selectable set of holograms each for a desired switching operation, and a pair of lenses between said first and second ferroelectric liquid crystal spatial light modulators for defining therebetween an interconnect region, wherein each spatial light modulator comprises a display screen, memory circuitry for storing a plurality of sets of hologram data, and selection circuitry for selecting one of said sets according to a desired switching function, each stored set of hologram data being calculated by:

• determining principal replay co-ordinates of a said hologram according to a desired switching function;
• using said co-ordinates, calculating the size in pixels of a base cell and evaluating a base cell pattern by a phase-quantization procedure;
• and
• replicating said base cell pattern data until the entire aperture of the spatial light modulator is filled.

A method of producing a phase-only computer generated hologram for a pixellated hologram device, having a respective (x,y) plane and a predetermined number of uniformly distributed phase levels, the method comprising:

• determining principal replay co-ordinates of a desired hologram;
• using said co-ordinates:
• calculating the size in pixels of a base cell;
• and
• evaluating a base cell pattern by a phase-quantization procedure;
• and
• replicating said base cell in the plane of the said hologram device until the entire aperture of the device is filled.

A method of operating an optical switch comprising an input optical fiber array and a receiver array, and an optical system connecting the input optical fiber array to the receiver array wherein the optical system comprises a first binary reconfigurable spatial light modulator, a second binary reconfigurable spatial light modulator, each spatial light modulator being adapted for providing a respective selectable set of holograms each for a desired switching operation, and a pair of lenses between said first and second binary reconfigurable spatial light modulators for defining therebetween an interconnect region, wherein each spatial light modulator comprises a display screen, memory circuitry for a plurality of sets of hologram data and selection circuitry for selecting one of said sets according to a desired switching function, each stored set of hologram data being calculated by:

• determining principal replay co-ordinates of a said hologram according to a desired switching function;
• using said co-ordinates, calculating the size in pixels of a base cell;
• and evaluating a base cell pattern by a phase-quantization procedure;
• and replicating said base cell pattern data until the entire aperture of the spatial light modulator is filled, the method comprising:
• scrolling the hologram pattern (in either 1- or 2-dimensions as appropriate) across the display device by one or more pixels at a time and at regular intervals.

A method of operating an optical switch comprising an input optical fiber array and a receiver array, and an optical system connecting the input optical fiber array to the receiver array wherein the optical system comprises a first ferroelectric liquid crystal spatial light modulator, a second ferroelectric liquid crystal spatial light modulator, each spatial light modulator being adapted for providing a respective selectable set of holograms each for a desired switching operation, and a pair of lenses between said first and second ferroelectric liquid crystal spatial light modulators for defining therebetween an interconnect region, wherein each spatial light modulator comprises a display screen, memory circuitry for a plurality of sets of hologram data and selection circuitry for selecting one of said sets according to a desired switching function, each stored set of hologram data being calculated by:

• determining principal replay co-ordinates of a said hologram according to a desired switching function;
• using said co-ordinates, calculating the size in pixels of a base cell;
• and evaluating a base cell pattern by a phase-quantization procedure;
• and replicating said base cell pattern data until the entire aperture of the spatial light modulator is filled, the method comprising:
• scrolling the hologram pattern (in either 1- or 2-dimensions as appropriate) across the display device by one or more pixels at a time and at regular intervals.