Wavelength characteristics control device, gain equalizer and light amplifier

A light amplifier for amplifying signal light and actively equalizing a gain-wavelength characteristic, comprising:

• amplifying means for amplifying the signal light;
• polarized light separating means for separating the amplified signal light into a plurality of separated polarized rays;
• polarization plane coincidence control means for making planes of polarization of the plurality of separated polarized rays coincident with each other, to thereby generate first polarized light;
• polarization variable control means for subjecting the plane of polarization of the first polarized light to rotatory control to change a ratio of a P-polarized ray to an S-polarized ray, to thereby generate polarization plane rotated light;
• a polarized light wavelength characteristic changing element passing the polarization plane rotated light, to thereby generate second polarized light having a wavelength characteristic corresponding to the changed ratio;
• polarization restoring means for subjecting the plane of polarization of the second polarized light to inverse rotatory control reverse to the rotatory control performed by said polarization variable control means on the plane of polarization of the first polarized light, to restore a polarized state identical with that of the first polarized light and thereby generate the third polarized light;
• and
• polarized light synthesizing means for synthesizing the third polarized light.

A gain equalizer comprising:

• a first birefringent device changing a light into a plane of polarized light;
• a first polarization rotator variably rotating the plane of polarized light;
• an optical filter filtering the rotated plane of polarized light;
• a second polarization rotator variable rotating the filtered, rotated plane of polarized light;
• and
• A second polarization device receiving the rotated, filtered, rotated plane of polarized light, gain equalizer thereby equalizing a gain-wavelength characteristic of the light.

A gain equalizer comprising:

• a first birefringent device changing a light into a plane of polarized light;
• a first polarization rotator variably rotating the plane of polarized light;
• an optical filter filtering the rotated plane of polarized light;
• a second polarization rotator variable rotating the filtered, rotated plane of polarized light;
• and
• a second birefringent device receiving the rotated, filtered, rotated plane of polarized light, then gain equalizer thereby equalizing a gain-wavelength characteristic of the light.

A gain equalizer for actively equalizing a gain-wavelength characteristic, comprising:

• a polarized light separator separating polarized signal light into a plurality of separated polarized rays;
• a polarization plane coincidence controller making planes of polarization of the plurality of separated polarized rays coincident with each other, to thereby generate first polarized light;
• a polarization variable controller subjecting the plane of polarization of the first polarized light to rotatory control to change a ratio of a P-polarized ray to an S-polarized ray, to thereby generate polarization plane rotated light;
• a polarized light wavelength characteristic changing element passing the polarization plane rotated light to thereby generate second polarized light having a wavelength characteristic corresponding to the changed ratio;
• a polarization restorer subjecting the plane of polarization of the second polarized light to inverse rotatory control reverse to the rotatory control performed by said polarization variable controller on the plane of polarization of the first polarized light, to restore a polarized state identical with that of the first polarized light and thereby generate third polarized light;
• and
• a polarized light synthesizer synthesizing the third polarized light.

A light amplifier for amplifying signal light and actively equalizing a gain-wavelength characteristic, comprising:

• an amplifier amplifying the signal light;
• a polarized light separator separating the amplified signal light into a plurality of separated polarized rays;
• a polarization plane coincidence controller making planes of polarization of the plurality of separated polarized rays coincident with each other, to thereby generate first polarized light;
• a polarization variable controller subjecting the plane of polarization of the first polarized light to rotatory control to change a ratio of a P-polarized ray to an S-polarized ray, to thereby generate polarization plane rotated light;
• a polarized light wavelength characteristic changing element passing the polarization plane rotated light, to thereby generate second polarized light having a wavelength characteristic corresponding to the changed ratio;
• a polarization restorer subjecting the plane of polarization of the second polarized light to inverse rotatory control reverse to the rotatory control performed by said polarization variable controller on the plane of polarization of the first polarized light, to restore a polarized state identical with that of the first polarized light and thereby generate the third polarized light;
• and
• a polarized light synthesizer synthesizing the third polarized light.

An apparatus comprising:

• a gain equalizer comprising:
• a polarized light separator separating polarized signal light into a plurality of separated polarized rays,
• a polarization plane coincidence controller making planes of polarization of the plurality of separated polarized rays coincident with each other, to thereby generate first polarized light,
• a polarization variable controller subjecting the plane of polarization of the first polarized light to rotatory control to change a ratio of a P-polarized ray to an S-polarized ray, to thereby generate polarization plane rotated light,
• a polarized light wavelength characteristic changing element passing the polarization plane rotated light to thereby generate second polarized light having a wavelength characteristic corresponding to the changed ratio,
• a polarization restorer subjecting the plane of polarization of the second polarized light to inverse rotatory control reverse to the rotatory control performed by said polarization variable controller on the plane of polarization of the first polarized light, to restore a polarized state identical with that of the first polarized light and thereby generate third polarized light, and
• a polarized light synthesizer synthesizing the third polarized light, to thereby actively equalize a gain-wavelength characteristic of the polarized signal light.

An apparatus comprising:

• a gain equalizer comprising:
• means for separating polarized signal light into a plurality of separated polarized rays,
• means for making planes of polarization of the plurality of separated polarized rays coincident with each other, to thereby generate first polarized light,
• means for subjecting the plane of polarization of the first polarized light to rotatory control to change a ratio of a P-polarized ray to an S-polarized ray, to thereby generate polarization plane rotated light,
• means for passing the polarization plane rotated light to thereby generate second polarized light having a wavelength characteristic corresponding to the changed ratio,
• means for subjecting the plane of polarization of the second polarized light to inverse rotatory control reverse to the rotatory control performed by said means for subjecting on the plane of polarization of the first polarized light, to restore a polarized state identical with that of the first polarized light and thereby generate third polarized light, and
• means for synthesizing the third polarized light, to thereby actively equalize a gain-wavelength characteristic of the polarized signal light.

A gain equalizer comprising:

• a first polarization device changing a light into a plane of polarized light;
• a first polarization rotator variably rotating the plane of polarized light;
• an optical filter filtering the rotated plane of polarized light;
• a second polarization rotator variable rotating the filtered, rotated plane of polarized light;
• and
• a second polarization device receiving the rotated, filtered, rotated plane of polarized light, the gain equalizer thereby equalizing a gain-wavelength characteristic of the light.

A gain equalizer comprising:

• a first birefringent device changing a light into a plane of polarized light;
• a first polarization rotator variably rotating the plane of polarized light;
• an optical filter filtering the rotated plane of polarized light;
• a second polarization rotator variable rotating the filtered, rotated plane of polarized light;
• and
• a second birefringent device receiving the rotated, filtered, rotated plane of polarized light, the gain equalizer thereby equalizing a gain-wavelength characteristic of the light.

A gain equalizer comprising:

• means for changing a light into a plane of polarized light;
• means for variably rotating the plane of polarized light;
• means for filtering the rotated plane of polarized light;
• means for variable rotating the filtered, rotated plane of polarized light, and
• means for passing the rotated, filtered, rotated plane of polarized light, the gain equalizer thereby equalizing a gain-wavelength characteristic of the light.

A method comprising:

• changing a light into a plane of polarized light;
• variably rotating the plane of polarized light;
• means for filtering the rotated plane of polarized light;
• variable rotating the filtered, rotated plane of polarized light;
• and
• passing the rotated, filtered, rotated plane of polarized light, the method thereby equalizing a gain-wavelength characteristic of the light.