JPH0590671A - Optical fiber amplifier by duplex excitation - Google Patents

Abstract

PURPOSE:To miniaturize a device and improve performance thereof, and to reduce cost by dividing one semiconductor laser beams for excitation into two by an optical branching apparatus, a branching ratio of which is varied, and using one beams for forward excitation and the other beams for reverse excitation. CONSTITUTION:Input rays 1 are amplified by employing one semiconductor laser 4 for duplex excitation. That is, excitation rays from the semiconductor laser 4 for duplex excitation with a drive power-supply temperature regulator 5 are passed through an isolator 3, and branched by an optical branching apparatus 21. One of excitation rays branched is multiplexed with input rays 1 by a photosynthesizer 2, and input rays 1 and excitation rays are projected to a laser medium 7 through an isolator 6. The other of excitation rays branched by the optical branching apparatus 21 is projected to the laser medium 7 through a photosynthesizer 9 and an isolator 8. Input rays 1 amplified by the laser medium 7 is output as output rays 10 through the isolator 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber amplifier by bidirectional pumping, which is applied to optical communication and optical measurement.

[0002]

2. Description of the Related Art In a conventional optical fiber-amplifier,
When a high gain is obtained by bidirectionally exciting the laser medium, one semiconductor laser is used for each of forward and backward pumping. (See Yoshida et al. "Development of optical fiber-amplifier" OQE 90-79, 1990) The oscillation wavelength of the pumping semiconductor laser used is mainly 1.48 .mu.m, and as shown in FIG. In the amplifier, since the bidirectional pumping is performed by using two semiconductor lasers, the size of the device is increased and the cost is increased.

Further, the gain of the conventional optical fiber amplifier depends on the wavelength of the pumping light, but the oscillation wavelength of the semiconductor laser is different for each laser element, so that two semiconductor lasers to be used are used. It was necessary to select the laser element so that the wavelengths of 1 and 2 are both excitation wavelengths that give the maximum gain.

A conventional optical fiber amplifier system using bidirectional pumping is shown in the flow chart of FIG. That is, the input light 1 is incident on the optical multiplexer 2, and the optical multiplexer 2 passes from the semiconductor laser 4 for forward pumping, which has passed through the isolator 3 and is controlled by the driving power source temperature controller 5. The excitation light and the input light 1 are multiplexed. The input light 1 and the excitation light pass through the isolator 6 and enter the laser medium 7. On the other hand, the reverse excitation semiconductor laser 12 controlled by the driving power source temperature controller 13
The excitation light from the optical path passes through the isolator 11 and the optical multiplexer 9
Then, it enters the laser medium 7 through the isolator 8.
The input light 1 amplified by the laser medium 7 is an isolator.
It is output as output light 10 through the filter 8.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is bidirectional pumping in an optical fiber-amplifier which is compact and has high performance, and which can reduce cost. The purpose is to provide the law.

[0006]

The present invention has been made in order to solve the above-mentioned technical problems. One pumping semiconductor laser light is divided into two by an optical branching device having a variable branching ratio. Then, an optical fiber-amplifier by bidirectional pumping is provided, in which one beam is used for forward pumping and the other beam is used for backward pumping.

[0007]

According to the configuration of the bidirectional pumping optical fiber amplifier of the present invention, one pumping semiconductor laser light is divided into two by the optical branching device, one light beam is forward pumped, and the other light beam is forwarded. Used for reverse excitation. Therefore, since the wavelengths used for pumping in the forward direction and the wavelength used in the reverse direction are exactly the same, it is sufficient to select one semiconductor laser that oscillates at the pumping wavelength at which the optical fiber amplifier gives the maximum gain. Becomes

In the optical fiber amplifier by bidirectional pumping according to the present invention, for example, by using a semiconductor laser that oscillates at a wavelength of 0.98 μm, which has a high gain efficiency with respect to an Er ³⁺ -doped optical fiber, After the laser light is branched for the direction pumping, there is no decrease in the gain due to the decrease in the optical output. This means that, for example, the gain efficiency is 10.2 dB / mW in the case of wavelength 0.98 μm pumping, and the wavelength 1.48 μm.
In the case of m excitation, it becomes 5.1 dB / mW.

Further, by using an optical branching device whose branching ratio can be changed, it is possible to arbitrarily set the ratio of the optical output used for the forward pumping and the backward pumping. Therefore, the most efficient excitation can be performed.

Next, the optical fiber amplifier by bidirectional pumping according to the present invention will be specifically described with reference to the accompanying drawings, but the present invention is not limited thereto.

[0011]

Embodiment 1 FIG. 2 shows a flow diagram of a processing process in an optical fiber amplifier by bidirectional pumping according to the present invention. That is, the input light 1 is transferred to one bidirectional pumping semiconductor laser.
Amplify using the 4. That is, the excitation light from the bidirectional excitation semiconductor laser 4 including the driving power source temperature controller 5 is
After passing through the isolator 3, it is branched by the optical branching device 21. One of the split excitation lights is multiplexed with the input light 1 by the optical multiplexer 2, and the input light 1 and the excitation light pass through the isolator 6 and enter the laser medium 7. The other side of the pumping light split by the optical splitter 21 is the optical multiplexer 9 and the isolator 8.
It enters the laser medium 7 through the laser beam. The input light 1 amplified by the laser medium 7 passes through the isolator 8 and is output as output light 10.

[0012]

As described above, the above-mentioned effects are obtained by the bidirectional pumping method in the optical fiber amplifier according to the present invention. Summarizing them, the following remarkable technical effects are obtained. That is, firstly, by providing bidirectional pumping using one pumping semiconductor laser, there is provided an optical fiber amplifier by bidirectional pumping which enables downsizing of the device, high efficiency, and cost reduction. Secondly, since the wavelengths used for forward and backward pumping are exactly the same, if one optical fiber-amplifier oscillates at the pumping wavelength that gives the maximum gain, one semiconductor laser can be selected. , Could provide an optical fiber amplifier with good bidirectional pumping.

Thirdly, since the branching ratio is variable, the ratio of pumping light powers used for forward and backward pumping can be arbitrarily set, and the optical fiber capable of the most efficient pumping can be set.
Provide an amplifier. Fourth, the above-mentioned small-sized, high-performance, low-cost optical fiber-amplifier is further used for optical communication,
It can be further applied to optical measurement.

[Brief description of drawings]

FIG. 1 is a flowchart showing a bidirectional pumping method in a conventional optical fiber amplifier.

FIG. 2 is a flowchart showing a bidirectional pumping method in the optical fiber amplifier according to the present invention.

[Explanation of symbols]

 1 Input Light 2, 9 Optical Multiplexer 4, 12 Excitation Semiconductor Laser 21 Optical Brancher 3, 6, 8, 11 Isolator 7 Laser Medium 5, 13 Drive Power Temperature Controller 10 Output Light

Claims (1)

[Claims] 1. A semiconductor laser light for pumping is divided into two by an optical branching device having a variable branching ratio, and one light beam is used for forward pumping and the other light beam is used for backward pumping. Fiber Optic Amplifier with Directional Pumping.