Light amplification medium control method, light amplification apparatus and system using the same

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said amplified light output passed through said first branching means branch, a light detection means for detecting the resulting light branch obtained by said second branching means, and a control means for controlling at least one of said excitation source and said return means on the basis of light power detected by said light detection means, wherein:

• said first branching means is constituted as a light coupler;
• and said return means is constituted by a light coupler for making the resulting light branch obtained by said first branching means branch into two directions, and an adjusting means for adjusting light power of the resulting two-directional light branches obtained by said light coupler and returning the adjusted two-directional light branches in reverse directions through said light coupler.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said amplified light output passed through said first branching means branch, a light detection means for detecting the resulting light branch obtained by said second branching means, a third branching means for making a part of said signal light input branch to said light amplification medium, a light detection means for detecting the resulting light branch obtained by said third branching means, and a control means for controlling at least one of said excitation source and said return means on the basis of light power detected by said light detection means, wherein:

• said first branching means is constituted as a light coupler;
• and said return means is constituted by a light coupler for making the resulting light branch obtained by said first branching means branch into two directions, and an adjusting means for adjusting light power of the resulting two-directional light branches obtained by said light coupler and returning the adjusted two-directional light branches in reverse directions through said light coupler.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said amplified light output passed through said first branching means branch, a third branching means for making a part of the resulting light branch obtained by said second branching means further branch, a first light detection means for detecting light through said third branching means, a second light detection means for detecting the resulting light branch obtained by said third branching means through a filter, and a control means for controlling at least one of said excitation source and said return means on the basis of detected light power, wherein:

• each of said first and second branching means is constituted as a light coupler;
• said light filter is constituted by a low-pass filter or a high-pass filter;
• and said return means is constituted by a light coupler for making the resulting light branch obtained by said first branching means branch into two directions, and an adjusting means for adjusting light power of the resulting two-directional light branches obtained by said light coupler and returning the adjusted two-directional light branches in reverse directions through said light coupler.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said light output passed through said first branching means branch, a light detection means for detecting the resulting light branch obtained by said second branching means, and a control means for controlling at least one of said excitation source and said return means on the basis of light power detected by said light detection means, wherein:

• said first branching means is constituted as a light coupler;
• and said return means is constituted by an adjusting means for adjusting light power of the resulting light branch obtained by said first branching means, and a reflection means for reflecting the light adjusted by said adjusting means in a reverse direction and returning the reflected light in a reverse direction through said adjusting means.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said amplified light output passed through said first branching means branch, a light detection means for detecting the resulting light branch obtained by said second branching means, a third branching means for making a part of said signal light input branch to said light amplification medium, a light detection means for detecting the resulting light branch obtained by said third branching means, and a control means for controlling at least one of said excitation source and said return means on the basis of light power from said light detection means, wherein:

• said first branching means is constituted as a light coupler;
• and said return means includes an adjusting means for adjusting light power of the resulting light branch obtained by said first branching means, and a reflection means for reflecting the light adjusted by said adjusting means in a reverse direction and returning the reflected light in a reverse direction through said adjusting means.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said amplified light output passed through said first branching means branch, a light detection means for detecting the resulting light branch obtained by said second branching means, and a control means for controlling at least one of said excitation source and said return means on the basis of light power detected by said light detection means, wherein said control means includes a comparator for detecting a deviation of light power detected by said first detection means from a predetermined reference value as an error signal, and a selector for selecting said error signal as a suppression control signal to said return means or as an excitation control signal to said excitation source, on the basis of the polarity of said error signal from said comparator.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said amplified light output through said first branching means branch, a light detection means for detecting the resulting light branch obtained by said second branching means, a third branching means for making a part of said signal light input branch to said light amplification medium, a light detection means for detecting the resulting light branch obtained by said third branching means, and a control means for controlling at least one of said excitation source and said return means on the. basis of light power detected by said light detection means, wherein said control means includes a comparator for detecting a deviation of light power detected by said first detection means from a predetermined reference value as an error signal and transmitting said error signal as an excitation control signal to said excitation source, a comparator for detecting a deviation of light power detected by said second detection means from a predetermined reference value as an error signal, and a selector for determining, on the basis of the polarity of said error signal from said comparator, whether a suppression control signal is to be transmitted to said return means or not.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said amplified light output passed through said first branching means branch, a third branching means for making a part of the resulting light branch obtained by said second branching means further branch, a light detection means for detecting light through said third branching means, a second light detection means for detection through said third branching means through a light filter, and a control means for controlling at least one of said excitation source and said return means on the basis of light power from said first light detection means and light power from said second light detection means, wherein said control means is constituted by a comparator for detecting a deviation of light power detected by said first detection means from a predetermined reference value as an error signal and transmitting said error signal as an excitation control signal to said excitation source, a comparator for detecting a deviation of light power detected by said second detection means from a predetermined reference value as an error signal, and a selector for determining, on the basis of the polarity of said error signal from said comparator, whether a suppression control signal is to be transmitted to said return means or not.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said return light from said return means to said first branching means branch, a first light detection means for detecting the resulting light branch obtained by said second branching means, a third branching means for making a part of the resulting return light returned to said light amplification medium and amplified by said light amplification medium branch, a second light detection means for detecting the resulting light branch obtained by said third branching means, and a control means for controlling at least one of said excitation source and said return means on the basis of light power detected by said first light detection means and light power detected by said second light detection means.

A light amplification apparatus comprising, as main constituent elements, a light amplification medium for providing an amplified light output upon excitation thereof, and an excitation source for exciting said light amplification medium so as to provide said amplified light output, and further comprising a first branching means for making a part of said amplified light output of said light amplification medium branch, a return means for returning the resulting light branch obtained by said first branching means to said light amplification medium through said first branching means in a direction reverse to the direction of said amplified light output, a second branching means for making a part of said return light from said return means to said first branching means branch, a first light detection means for detecting the resulting light branch obtained by said second branching means, a third branching means for making a part of the resulting return light returned to said light amplification medium and amplified by said light amplification medium branch, a second light detection means for detecting the resulting light branch obtained by said third branching means, and a control means for controlling at least one of said excitation source and said return means on the basis of light power detected by said first light detection means and light power detected by said second light detection means, wherein said control means is constituted by a divider for calculating a ratio of light power between light power detected by said first light detection means and light power detected by said second light detection means, a comparator for detecting a deviation of the ratio of light power obtained by said divider from a predetermined reference value as an error signal, and a selector for selecting said error signal as a suppression control signal to said return means or as an excitation control signal to said excitation source on the basis of the polarity of said error signal from said comparator.

A light amplification apparatus comprising:

• a light amplification medium for providing an amplified light output upon excitation thereof;
• an excitation source for exciting the light amplification medium so as to provide the amplified light output;
• branching means for making a part of the amplified light output of the light amplification medium branch;
• and
• return means for returning the resulting light branch obtained by the branching means to the light amplification medium in a direction reverse to a direction of the amplified light output.

A method of controlling a light amplification medium in a light amplification apparatus, the light amplification apparatus including the light amplification medium and an excitation source for exciting the light amplification medium so as to provide an amplified light output, the method comprising the steps of:

• making a part of the amplified light output of the light amplification medium branch;
• amplifying the resulting light branch based on a prediction of a light surge;
• and
• returning the amplified light branch to the light amplification medium in a direction reverse to a direction of the amplified light output.

A light amplification apparatus comprising:

• a light amplification medium for providing an amplified light output upon excitation thereof;
• an excitation source for exciting the light amplification medium so as to provide the amplified light output;
• first branching means for making a part of the amplified light output of the light amplification medium branch;
• return means for returning the resulting light branch obtained by the first branching means to the light amplification medium through the first branching means in a direction reverse to a direction of the light output;
• second branching means for making a part of the amplified light output which has passed through the first branching means branch;
• first light detection means for detecting the resulting light branch obtained by the second branching means;
• third branching means for making a part of a light input introduced into the light amplification medium branch;
• second light detection means for detecting the resulting light branch obtained by the third branching means;
• and
• control means for controlling at least one of the excitation source and the return means based on a light power detected by the first light detection means and a light power detected by the second light detection means.

A light amplification apparatus comprising:

• a light amplification medium for providing an amplified light output upon excitation thereof;
• an excitation source for exciting the light amplification medium so as to provide the amplified light output;
• branching means for making a part of the amplified light output of the light amplification medium branch;
• and
• return means for returning at least the resulting light branch obtained by the branching means to the light amplification medium in a direction reverse to a direction of the amplified light output based on a prediction of a light surge.

A light amplification apparatus comprising:

• a light amplification medium for providing an amplified light output upon excitation thereof;
• an excitation source for exciting the light amplification medium so as to provide the amplified light output;
• branching means for making a part of the amplified light output of the light amplification medium branch;
• and
• return means for amplifying the resulting light branch obtained by the branching means based on a prediction of a light surge, and returning the amplified light branch to the light amplification medium in a direction reverse to a direction of the amplified light output.

A light amplification apparatus comprising:

• a light amplification medium for providing an amplified light output upon excitation thereof;
• an excitation source for exciting the light amplification medium so as to provide the amplified light output;
• first branching means for making the amplified part of a light output of the light amplification medium branch;
• return means for returning the resulting light branch obtained by the first branching means to the light amplification medium in a direction reverse to a direction of the amplified light output;
• second branching means for making a part of the amplified light output of the light amplification medium branch;
• light detection means for detecting the resulting light branch obtained by the second branching means;
• and
• control means for controlling at least one of the excitation source and the return means based on a light power detected by the light detection means.

A light amplification apparatus comprising:

• a light amplification medium for providing an amplified light output upon excitation thereof;
• an excitation source for exciting the light amplification medium so as to provide the amplified light output;
• first branching means for making the amplified part of a light output of the light amplification medium branch;
• return means for returning the resulting light branch obtained by the first branching means to the light amplification medium through the first branching means in a direction reverse to a direction of the amplified light output;
• second branching means for making a part of the amplified light output which has passed through the first branching means branch;
• light detection means for detecting the resulting light branch obtained by the second branching means;
• and
• control means for controlling at least one of the excitation source and the return means based on a light power detected by the light detection means.