Optical circuit and light transmission system and method using the same

A light transmission system comprising

• a light transmitter for sending out light,
• at least one optical amplifier for amplifying the sent light,
• an optical circuit for passing the amplified light, said optical circuit comprising:
• (a) a plurality of light input and output units for at least one of receiving and emitting light,
• (b) a polarized light separating and combining element for separating an incident light from at least one light input and output unit of the plurality of light input and output units into two separated polarized lights, and for combining the two separated polarized lights into a combined light to be emitted into at least another of the plurality of light input and output units,
• (c) polarized light rotating means for rotating the two separated polarized lights at a plurality of specific different angles, and
• (d) a wavelength dispersing element for dispersing polarized light of a specific wavelength, wherein
• each one of the plurality of specific angles rotated by the polarized light rotating means is such an angle as to emit the incident light incoming from the one light input and output unit to the other light input and output unit, and to prevent an emission of further light incoming from the other light input and output unit to the one light input and output unit, and
• a light receiver for receiving the combined light passed by said optical circuit.

A light transmission system comprising:

• a plurality of light transmitting and receiving units for transmitting and receiving light,
• an optical circuit group possessing a plurality of optical circuits for passing the light transmitted between the plurality of light transmitting and receiving units, each one of said plurality of optical circuits comprising:
• (a) a plurality of light input and output units for at least one of receiving and emitting light,
• (b) a polarized light separating and combining element for separating an incident light from at least one light input and output unit of the plurality of light input and output units into two separated polarized lights, and for combining the two separated polarized lights into a combined light to be emitted into at least another of the plurality of light input and output units,
• (c) polarized light rotating means for rotating the two separated polarized lights at a plurality of specific different angles, and
• (d) a wavelength dispersing element for dispersing polarized light of a specific wavelength, wherein
• each one of the plurality of specific angles rotated by the polarized light rotating means is such an angle as to emit the incident light incoming from the one light input and output unit to the other light input and output unit, and to prevent an emission of further light incoming from the other light input and output unit to the one light input and output unit, and
• at least one optical amplifier for amplifying the combined light passed by the optical circuit group.

A method of transmitting light comprising the steps of:

• (a) separating an incident light from at least a first light input and output unit into two separated polarized lights;
• (b) rotating the two separated polarized lights at a plurality of specific different angles;
• (c) dispersing the two separated polarized lights of a specific wavelength;
• (d) rotating the two separate polarized lights at a further plurality of specific different angles;
• and
• (e) combining the two separated polarized lights into a combined light to be emitted into at least a second light input and output unit, wherein
• each one of the plurality of specific angles and the further plurality of specific angles that is rotated is such an angle as to emit the incident light incoming from the first light input and output unit to the second light input and output unit, and to prevent an emission of further light incoming from the second light input and output unit to the first light input and output unit.

An optical circuit comprising:

• a polarized light separating and combining element for receiving an incident light and for separating the incident light into two polarized lights by deflecting the incident light,
• a first polarized light rotating means for rotating the two polarized lights at a first plurality of specific different angles,
• a wavelength dispersing element for wavelength-dispersing each of the two polarized lights rotated by said first polarized light rotating means,
• a second polarized light rotating means for rotating the two polarized lights wavelength-dispersed by said wavelength dispersing element at a second plurality of specific different angles, said second plurality of specific different angles being different from said first plurality of specific different angles, wherein
• said polarized light separating and combining element receives the two polarized lights rotated by said second polarized light rotating means, and combines the received two polarized lights into a combined light, and
• each one of the first and second plurality of specific different angles is such an angle as to permit the combining of the two polarized lights received by said polarized light separating and combining element into the combined light, and to prevent said polarized light separating and combining element from combining two further polarized lights into a further combined light, said two further polarized lights being passed through said second polarized light rotating means, said wavelength dispersing element and said first polarized light rotating means, respectively.