Method of aligning optical fibers to a multi-port optical assembly
First Claim
1. A method of assembling an optical device for selectively coupling optical signals among a unidirectional input port, a unidirectional output port and a bidirectional port comprising steps of:
- securing input and output optical fibers in a fixed generally parallel relationship;
forming a stack of polarization-manipulating elements such that said stack includes input and output ports on a forward side of said stack and a bidirectional port on a rearward side opposite to said forward side, including positioning a controllable multi-state element within said stack such that an input beam from said input port is optically coupled to said bidirectional port when said controllable multi-state element is in a first state and such that an input beam from said output port is optically coupled to said bidirectional port when said multi-state controllable element is in a second state;
directing light from said forward side of said stack toward said rearward side and selectively switching said controllable multi-state element to detect whether said bidirectional port is optically coupled to said input port and optically isolated from said output port when said controllable multi-state element is in said first state and to detect whether said bidirectional port is optically isolated from said input port and optically coupled to said output port when said controllable multi-state element is in said second state; and
upon detecting that said selective optical couplings from said input and output ports to said bidirectional port exist, optically aligning a bidirectional optical fiber on said rearward side of said stack with a selected one of said input and output optical fibers on said forward side, wherein said step of directing said light and said step of optically aligning said bidirectional optical fiber are achieved without directing light from said stack to said input and output ports.
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Abstract
A method of assembling an optical device for coupling optical fibers to a corresponding number of input/output ports of a stack of optical elements includes utilizing at least one controllable multi-state optical element to selectively switch the optical coupling among the ports. The controllable multi-state element is one element within a stack of polarization-manipulating elements having a configuration that allows the condition of the multi-state element or elements to dictate the optical coupling among the ports. In the preferred embodiment, the multi-state element is a Faraday rotator. The method may be used in either or both of a quality control application or a fiber-to-port alignment application. In the quality control operation, the stack of polarization-manipulating elements is tested to verify proper operation with respect to separating and selectively recombining polarization components of input beams. In the fiber-to-port alignment application, the fibers on the same side of the stack are first fixed in a parallel relationship with a known center-to-center distance that is equal to the center-to-center distance between corresponding ports of the stack. By optically aligning one of the fibers on the forward side of the stack with the fibers on the rearward side of the stack, at least one other fiber is automatically brought into registration with its corresponding port.
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Citations
17 Claims
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1. A method of assembling an optical device for selectively coupling optical signals among a unidirectional input port, a unidirectional output port and a bidirectional port comprising steps of:
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securing input and output optical fibers in a fixed generally parallel relationship; forming a stack of polarization-manipulating elements such that said stack includes input and output ports on a forward side of said stack and a bidirectional port on a rearward side opposite to said forward side, including positioning a controllable multi-state element within said stack such that an input beam from said input port is optically coupled to said bidirectional port when said controllable multi-state element is in a first state and such that an input beam from said output port is optically coupled to said bidirectional port when said multi-state controllable element is in a second state; directing light from said forward side of said stack toward said rearward side and selectively switching said controllable multi-state element to detect whether said bidirectional port is optically coupled to said input port and optically isolated from said output port when said controllable multi-state element is in said first state and to detect whether said bidirectional port is optically isolated from said input port and optically coupled to said output port when said controllable multi-state element is in said second state; and upon detecting that said selective optical couplings from said input and output ports to said bidirectional port exist, optically aligning a bidirectional optical fiber on said rearward side of said stack with a selected one of said input and output optical fibers on said forward side, wherein said step of directing said light and said step of optically aligning said bidirectional optical fiber are achieved without directing light from said stack to said input and output ports. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of optically coupling a first fiber to a second fiber and optically coupling said second fiber to a third fiber comprising steps of:
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forming an array of side-by-side optical elements such that polarization components of beams propagating through said array are separated and then selectively recombined, including arranging a plurality of walk-off crystals and a Faraday rotator within said array such that said selective recombination of polarization components is dependent upon a state of a magnetic field applied to said Faraday rotator; switching said applied magnetic field between first and second states, thereby shifting said Faraday rotator between first and second polarization rotation conditions for rotating polarization components propagating through said Faraday rotator, said switching comprising reversing a polarity of said applied magnetic field; identifying relative positions of first, second and third ports on said array based upon said recombinations of said polarization components, wherein polarization components of a first beam that is introduced into said array at said first port are separated and then recombined at said second port when said applied magnetic field is in said first state and wherein polarization components of a second beam that is introduced into said array at said third port are separated and then recombined at said second port when said applied magnetic field is in said second state; and aligning said first, second and third fibers to said first, second and third ports, respectively. - View Dependent Claims (10, 11, 12)
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13. A method of ascertaining proper operation of an optical assembly having selective coupling among first, second and third input/output ports comprising steps of:
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forming a stack of polarization-manipulating optical elements such that first and third ports are on a forward side and a second port is on a rearward side of said stack, said optical elements including a plurality of polarization walk-off elements and at least one polarization rotation element that is responsive to application of a magnetic field; positioning a light source at one of said forward and rearward sides of said stack and a light detector at the other of said forward and rearward sides such that propagation of light between said second port and said first and third ports is detectable; manipulating a magnetic field applied to at least one of said polarization rotation elements to switch between first and second states that are distinguishable with respect to rotating polarization components of beams; detecting whether said first state induces optical coupling between said first and second ports and optical isolation between said second and third ports; and detecting whether said second state induces optical coupling between said second and third ports and optical isolation between said first and second ports. - View Dependent Claims (14, 15, 16, 17)
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Specification