Apparatus and method for optical equalization and amplification

An optical equalizing amplifier for equalizing a multiwavelength light, comprising:

• a first optical fiber amplifying unit for receiving and amplifying the multiwavelength light in accordance with an excitation light provided to said first optical fiber amplifying unit;
• a light source for providing the excitation light to said first optical fiber amplifying unit;
• a variable optical attenuator for adjusting an optical level of a multiwavelength light output from said first optical fiber amplifying unit;
• and
• control means for controlling a light intensity of said light source in such a way that optical levels of a plurality of wavelength bands in the multiwavelength light output from said first optical fiber amplifying unit match each other irrespective of wavelength dependency of the optical levels of the plurality of wavelength bands in the multiwavelength light when received by the first optical fiber amplifying unit, and for controlling attenuation of said variable optical attenuator in such a way that the optical level of the multiwavelength light output from said variable optical attenuator is kept constant.

An optical equalizing amplifier for equalizing a multiwavelength light, comprising:

• an optical fiber amplifying unit for receiving and amplifying the multiwavelength light with a plurality of optical fiber amplifiers connected in series, said optical fiber amplifiers having different amplification characteristics dependant on wavelength;
• a plurality of light sources for providing excitation lights to the plurality of optical fiber amplifiers;
• and
• control means for controlling each light intensity of said plurality of light sources in such a way that each of optical levels of a plurality of wavelength bands in the multiwavelength light output from said optical fiber amplifying unit matches each other irrespective of wavelength dependency of the optical levels of the plurality of wavelength bands in the multiwavelength light when received by the optical fiber amplifying unit.

An optical equalizer for equalizing a multiwavelength light, comprising:

• an optical fiber amplifying unit for amplifying a multiwavelength light;
• a variable optical attenuator for adjusting an optical level of the multiwavelength light input to said optical fiber amplifying unit;
• and
• control means for selecting a plurality of wavelength bands from a portion of the multiwavelength light output from said optical fiber amplifying unit and for controlling attenuation of said variable optical attenuator in such a way that each optical level of each wavelength band matches each other.

An optical equalizing amplifier for equalizing a multiwavelength light, comprising:

• optical level adjusting means for adjusting an optical level of a multiwavelength light;
• an optical fiber amplifying unit for amplifying the multiwavelength light output from said optical level adjusting means in accordance with an excitation light provided to said optical fiber amplifying unit;
• a light source for providing the excitation light to said optical fiber amplifying unit;
• and
• control means for controlling a light intensity of the light source in such a way that the optical level of the multiwavelength light output from said optical fiber amplifying unit is kept constant, and for controlling said optical level adjusting means so as to equalize optical levels of a plurality of wavelength bands in the multiwavelength light output from said optical fiber amplifying unit.

An optical equalizing amplifier for equalizing a multiwavelength light, comprising:

• an optical fiber amplifying unit for amplifying the multiwavelength light in accordance with an excitation light provided to said optical fiber amplifying unit;
• a light source for providing the excitation light to said optical fiber amplifying unit;
• optical level adjusting means for adjusting an optical level of a multiwavelength light output from said optical fiber amplifying unit;
• and
• control means for controlling a light intensity of the light source so as to equalize optical levels of a plurality of wavelength bands in the multiwavelength light output from said optical fiber amplifying unit, and for controlling said optical level adjusting means in such a way that the optical level of the multiwavelength light output from said optical level adjusting means is kept constant.

An optical equalizer for equalizing a multiwavelength light, comprising:

• an optical fiber amplifying unit for receiving and amplifying a multiwavelength light;
• optical level adjusting means for adjusting an optical level of the multiwavelength light input to said optical fiber amplifying unit;
• and
• control means for controlling said optical level adjusting means in such a way that each optical level of each of a plurality of wavelength bands in the multiwavelength light output from said optical fiber amplifying unit matches each other irrespective of wavelength dependency of the optical levels when the multiwavelength light is received by the optical fiber amplifying unit.

An optical equalizing amplifier for equalizing a multiwavelength light, comprising:

• optical level adjusting means for adjusting an optical level of a wavelength division multiplexed optical light;
• optical fiber amplifying unit for amplifying the multiwavelength light output from said optical level adjusting means;
• a light source for providing an excitation light to said optical fiber amplifying unit;
• and
• branch means comprising a plurality of wavelength transmission bands for generating a plurality of lights having different wavelength components from a portion of the multiwavelength light amplified by said optical fiber amplifying unit;
• and
• control means for controlling a light intensity of the light source in such a way that the optical level of the multiwavelength light output from said optical fiber amplifying unit is kept constant, and for controlling said optical level adjusting means based on a plurality of optical levels output from said branch means.

An optical amplifying/equalizing method for equalizing a multiwavelength light, comprising the steps of:

• adjusting an optical level of the multiwavelength light using a variable optical attenuator;
• amplifying the multiwavelength light whose optical level has been adjusted by the variable optical attenuator, the amplifying being performed by an optical fiber amplifier in accordance with an excitation light provided to the optical fiber amplifier;
• controlling the optical level of the excitation light provided to the optical fiber amplifier in such a way that the optical level of the multiwavelength light output from the optical fiber amplifier is kept constant, and
• controlling attenuation of the variable optical attenuator so as to equalize optical levels of a plurality of wavelength bands in the multiwavelength light.

An optical equalizing/amplifying method for equalizing a multiwavelength light, comprising the steps of:

• amplifying the multiwavelength light using an optical fiber amplifier in accordance with an excitation light provided to the optical fiber amplifier;
• adjusting, using a variable optical attenuator, an optical level of the multiwavelength light amplified by the optical fiber amplifier;
• controlling the optical level of the excitation light provided to the optical fiber amplifier so as to equalize the output level of a plurality of wavelength bands in the multiwavelength light;
• and
• controlling attenuation of the variable optical attenuator in such a way that the optical level of the multiwavelength light output from the variable optical attenuator is kept constant.

An optical equalizing amplifier for equalizing a multiwavelength light, comprising:

• a variable optical attenuator for adjusting an optical level of the multiwavelength light;
• a first optical fiber amplifying unit for amplifying a multiwavelength light output from the variable optical attenuator in accordance with an excitation light provided to the first optical fiber amplifying unit;
• a light source for providing the excitation light to the first optical fiber amplifying unit;
• and
• control means for controlling a light intensity of the light source in such a way that the optical level of the multiwavelength light output from the first optical fiber amplifying unit is kept constant, and for controlling attenuation of the variable optical attenuator in such a way that each of optical levels of a plurality of wavelength bands in the multiwavelength light output from the first optical fiber amplifying unit matches each other,
• wherein the control means makes a portion of the multiwavelength light output from the first optical fiber amplifying unit branch into a plurality of wavelength bands, and controls attenuation of the variable optical attenuator such that a detected optical level of a shortest wavelength band equals a detected optical level of a longest wavelength band of wavelength bands whose optical levels exceed a predetermined level.

An optical equalizing amplifier for equalizing a multiwavelength light, comprising:

• a first optical fiber amplifying unit for amplifying the multiwavelength light in accordance with an excitation light provided to the first optical fiber amplifying unit;
• a light source for providing the excitation light to the first optical fiber amplifying unit;
• a variable optical attenuator for adjusting an optical level of a multiwavelength light output from the first optical fiber amplifying unit;
• and
• control means for controlling a light intensity of the light source in such a way that optical levels of a plurality of wavelength bands in the multiwavelength light output from the first optical fiber amplifying unit match each other, and for controlling attenuation of the variable optical attenuator in such a way that the optical level of the multiwavelength light output from the variable optical attenuator is kept constant,
• wherein the control means makes a portion of the multiwavelength light output from the first optical fiber amplifying unit branch into a plurality of wavelength bands, and controls the light intensity of the light source such that a detected optical level of a shortest wavelength band equals a detected optical level of a longest wavelength band of wavelength bands whose optical levels exceed a predetermined level.

An apparatus for amplifying a multiwavelength light including first and second wavelength bands at first and second optical levels, respectively, the apparatus comprising:

• a variable optical attenuator adjusting the first and second optical levels in the multiwavelength light;
• an optical amplifier amplifying the first and second optical level adjusted multiwavelength light;
• and
• a controller controlling the optical amplifier to maintain the amplified multiwavelength light at a constant power level, and controlling the variable optical attenuator to equalize the first and second optical levels in the amplified multiwavelength light.

An apparatus for amplifying a multiwavelength light including first and second wavelength bands at first and second optical levels, respectively, the apparatus comprising:

• an optical amplifier amplifying the multiwavelength light;
• a variable optical attenuator adjusting the first and second optical levels in the amplified multiwavelength light;
• and
• a controller controlling the optical amplifier to equalize the first and second optical levels, and controlling the variable optical attenuator to maintain the amplified multiwavelength light at a constant power level.

A method for amplifying a multiwavelength light including first and second wavelength bands at first and second optical levels, respectively, the method comprising the steps of:

• adjusting the first and second optical levels in the multiwavelength light;
• and
• amplifying the first and second optical level adjusted multiwavelength light, wherein
• the amplifying step maintains the amplified multiwavelength light at a constant power level, and
• the adjusting step equalizes the first and second optical levels in the amplified multiwavelength light.

A method for amplifying a multiwavelength light including first and second wavelength bands at first and second optical levels, respectively, the method comprising the steps of:

• amplifying the multiwavelength light;
• and
• adjusting the first and second optical levels in the amplified multiwavelength light, wherein
• the amplifying step equalizes the first and second optical levels, and
• the adjusting step maintains the amplified multiwavelength light at a constant power level.