JP2744465B2 - Light tap - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical tap used in an optical LAN or the like, for branching and extracting signal light in the middle of a transmission path.

(Prior Art) FIG. 2 is a configuration diagram of an optical fiber transmission system using a conventional optical tap.

In FIG. 2, reference numeral 1 denotes a 1.5 μm band light source, which emits light having a wavelength in a 1.5 μm band (1.51 to 1.57 μm). Reference numeral 2 denotes a transmission path optical fiber through which light having a wavelength in the 1.5 μm band from the light source 1 is propagated. Reference numeral 3 denotes an optical tap, which is constituted by a 2 × 2 optical star coupler 3a.

This optical star coupler 3a is propagated through the optical fiber 2.
1.5 μm band wavelength light is incident on one incident end and splits into two,
One branch light is emitted as a tap output from one emission end, and the other branch light is emitted from the remaining emission end to the transmission path optical fiber 4 of the next stage. A light receiving element 5 receives the tap output from the optical tap 3.

In such a configuration, 1.
After being transmitted through the optical fiber 2, the wavelength light in the 5 μm band is incident on one incident end of the optical star coupler 3a and is branched into two. One of the branched lights is emitted from one emission end, propagates to the transmission path optical fiber 4 at the next stage, and is received by the light receiving element 5. On the other hand, the other branched light is emitted from the remaining emission end as a tap output.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional optical tap, the optical power of the wavelength in the 1.5 μm band is subjected to optical branch loss in the 2 × 2 optical star coupler 3a for each optical tap. There is a disadvantage that the number of tap points is restricted.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide an optical tap having a simple configuration, capable of compensating for an optical branch loss, and increasing the number of tap points in a transmission system.

(Means for Solving the Problems) To achieve the above object, in claim (1), an excitation light source for emitting excitation light, and a 1.5 μm band wavelength light transmitted through the excitation light and an optical fiber are provided. An optical star coupler that splits the multiplexed light and emits the split light, a rare-earth element-doped optical fiber amplifier that receives one split light of the optical star coupler and amplifies the 1.5 μm band wavelength light. With.

Further, in claim (2), a combined light of a pump light source for emitting pump light, a 1.5 μm band wavelength light transmitted through an optical fiber, and the pump light is incident, and the 1.5 μm band wavelength light is emitted. And a 1.5 μm band wavelength light amplified by the rare earth element-doped optical fiber amplifier and the pumping light by the pumping light source, and the combined light is branched and emitted. An optical star coupler was provided.

(Operation) According to claim (1), the 1.5 μm-band wavelength light transmitted through the optical fiber and the pump light from the pump light source are incident on the optical star coupler and multiplexed. The optical star coupler emits the combined light, for example, into two branches.

Next, one of the branched lights is incident on a rare earth element-doped optical fiber amplifier. As a result, the rare earth element-doped optical fiber amplifier is in an excited state, and amplifies light having a wavelength in the 1.5 μm band. By this amplifying action, the optical loss due to the optical fiber and the optical branch loss due to the optical star coupler are compensated. Next, the 1.5 μm-band wavelength light that has undergone the amplifying action is sent to the next-stage transmission line optical fiber.

On the other hand, the other branched light by the optical star coupler is emitted as a tap output and received at the tap point.

According to claim (2), the multiplexed light of the 1.5 μm-band wavelength light and the excitation light transmitted through the optical fiber is incident on the rare-earth element-doped optical fiber amplifier. As a result, the rare-earth-doped optical fiber amplifier is in an excited state, and 1.
Amplifies light in the 5 μm band. By this amplifying action, the optical loss due to the optical fiber and the optical branch loss due to the next-stage optical star coupler are compensated.

Next, the 1.5 μm band light having undergone the amplification action is incident on an optical star coupler and multiplexed with pumping light from a pumping light source. The optical star coupler emits the combined light, for example, into two branches.

Next, one of the branched lights is sent to the transmission path optical fiber at the next stage.

On the other hand, the other branched light by the optical star coupler is emitted as a tap output, and is examined at the tap point.

(Embodiment) FIG. 1 is a configuration diagram showing a first embodiment of an optical fiber transmission system using an optical tap according to the present invention, and the same components as those in FIG. Is represented by That is, reference numeral 1 denotes a 1.5 μm band light source and a 1.5 μm band light source (1.51 to 1.57 μm).
m) is emitted. 2 is an optical fiber for a transmission line,
Light having a wavelength of 1.5 μm band is propagated by the light source 1.

10 is an optical tap, which is an excitation light source 11 and a 2x2 optical star coupler 1
2 and a rare earth element-doped optical fiber amplifier 13.

The excitation light source 11 has, for example, an oscillation wavelength of 1.48 μm band (1.41 to 1.41 μm).
1.49 μm) and emits excitation light at a predetermined intensity (several tens mW).

2x2 optical star coupler 12 propagated through optical fiber 2
The 1.5 μm band wavelength light is incident on one incident end, and the excitation light from the excitation light source 11 is incident on the remaining incident ends, respectively, and multiplexed. Emit.

The rare-earth element-doped optical fiber amplifier (hereinafter, referred to as an optical fiber amplifier) 13 is configured by adding a rare-earth element, for example, erbium (hereinafter, referred to as Er) to an optical fiber at a predetermined concentration. The optical fiber amplifier 13 has one end connected to one output end of the optical star coupler 12 and the other end connected to one end of the optical fiber 4 for a transmission path. Based on this, the wavelength light in the 1.5 μm band is amplified and sent to the optical fiber 4.

Reference numeral 21 denotes an optical filter, which receives the other branched light from the optical star coupler 12 and transmits only the 1.5 μm band light, and blocks other wavelength light, ie, the 1.48 μm excitation light and spontaneous emission light. I do.

Reference numeral 22 denotes a light receiving element which receives light having a wavelength of 1.5 μm band transmitted through the optical filter 21.

 Next, the operation of the above configuration will be described.

The 1.5 μm wavelength light emitted from the light source 1 is transmitted to the optical fiber 4. 1. This optical fiber 4
Light having a wavelength in the 5 μm band reaches the optical tap 10, enters one input end of the optical star coupler 12, and is branched into two.

On the other hand, excitation light of a wavelength of 1.48 μm by the excitation light source 11 is incident on the remaining incident end of the optical star coupler 12.
The optical star coupler 12 multiplexes these incident lights, splits the multiplexed light into two, and makes one of the split lights into one end of the optical fiber amplifier 13.

The optical fiber amplifier 13 is brought into an excited state by the incidence of the pump light, whereby the light having a wavelength in the 1.5 μm band is subjected to an amplifying action. By this amplifying action, the optical loss of the 1.5 μm wavelength light by the optical fiber 2 and the optical branch loss by the optical star coupler 12 are compensated. Next, the 1.5 μm band wavelength light subjected to the amplification action is sent to the transmission line optical fiber 4 at the next stage.

On the other hand, the other branched light by the optical star coupler 12 is emitted as a tap output and is incident on the optical filter 21. The optical filter 21 transmits only light having a wavelength in the 1.5 μm band, and blocks excitation light and spontaneous emission light of the optical fiber amplifier 13. As a result, the light receiving element 22 receives only the 1.5 μm wavelength light, converts the light into an electric signal, and then processes the electric signal by a processor (not shown).

As described above, according to the first embodiment, the 1.5 μm wavelength light transmitted through the optical fiber 2 and the pump light
With the pumping light by the optical star coupler 12, split the combined light into two, and split one of the split lights into an optical fiber amplifier.
After being amplified at 13, it is sent to the optical fiber 4 of the next stage, and the other branch light by the optical star coupler 12 is configured to be a tap output. An optical tap that can compensate for the loss and the optical branch loss due to the optical star coupler 12 and can increase the number of tap points in the system is realized.

FIG. 3 is a configuration diagram showing a second embodiment of the optical fiber transmission system using the optical tap according to the present invention.

The difference between the second embodiment and the first embodiment is that an excitation light source 23 similar to the excitation light source 11 and a 2 × 2 optical star coupler 24 are provided on the light source 1 side, and the optical star coupler 24 has a wavelength of 1.5 μm. Band wavelength light and pump light are multiplexed, and this multiplexed light is
And an optical fiber amplifier 13a is arranged on one side of the input end of the optical star coupler 12 on the optical tap 10 side to amplify the 1.5 μm band wavelength light transmitted through the optical fiber 2. After that, the optical star coupler 12 multiplexes the pump light with the pump light, further divides the multiplexed light to obtain an optical tap output, and sends out the 1.5 μm band wavelength light to the next stage optical fiber 4. It is to be configured.

Even in such a configuration, the same effect as in the first embodiment can be obtained.

(Effect of the Invention) As described above, according to claim (1), the pump light source that emits the pump light is combined with the 1.5 μm band light transmitted through the optical fiber. An optical star coupler that splits the combined light and emits the combined light, and a rare earth element-doped optical fiber amplifier that receives one branched light of the optical star coupler and amplifies the 1.5 μm band wavelength light. An optical tap is constituted, and in claim (2), an excitation light source for emitting excitation light and 1.5 μm transmitted through an optical fiber are provided.
The combined light of the m-band wavelength light and the pump light is incident, and the 1.5 μm
Rare-element-doped optical fiber amplifier for amplifying band wavelength light, 1.5 μm-band wavelength light amplified by the rare earth element-doped optical fiber amplifier, and pump light from the pump light source are combined, and the combined light is branched. And an optical tap having an optical star coupler that emits the light, the optical loss due to the optical fiber and the optical branching loss due to the optical star coupler can be compensated with a simple configuration, and the number of tap points in the system can be reduced. There is an advantage that it can be increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an optical fiber transmission system using an optical tap according to the present invention, FIG. 2 is a configuration diagram of an optical fiber transmission system using a conventional optical tap, and FIG. FIG. 4 is a configuration diagram showing a second embodiment of the optical fiber transmission system using the optical tap according to the present invention. In the figure, 1 ... 1.5 μm band light source, 2,4 ... optical fiber for transmission line, 12,24 ... 2x2 optical star coupler, 11,23 ... excitation light source, 13,13a ... Er (rare earth element) Additive optical fiber amplifier, 21 ... Optical filter, 22 ... Light receiving element.

Claims (2)

(57) [Claims] 1. An optical star coupler that combines an excitation light source that emits excitation light, a 1.5 μm band wavelength light transmitted through an optical fiber, and the excitation light, and branches and emits the combined light. One branch light of the optical star coupler is incident, and the 1.5 μm
An optical tap comprising: a rare earth element-doped optical fiber amplifier for amplifying light in a wavelength band. 2. A rare earth element which receives a pump light source for emitting pump light, a combined light of 1.5 μm band wavelength light and pump light transmitted through an optical fiber, and amplifies the 1.5 μm band wavelength light. Element-doped optical fiber amplifier, and amplified by the rare earth element-doped optical fiber amplifier 1.
An optical tap, comprising: an optical star coupler that multiplexes light having a wavelength in the 5 μm band and pumping light from the pumping light source, and branches and outputs the combined light.