JP2004193244A - Ase light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ASE light source whose output is stable over a wide band and the whole band. <P>SOLUTION: A first ASE light source device 2 is provided with a 3dB coupler 10. The stimulation light of a stimulation light source device 8 is inputted from one port 10a between first and second input/output ports at one end side of the 3dB coupler 10, and output ASE light of a second ASE light source device 3 is inputted from the other port 10b. Third and fourth input/output ports 10c and 10d at the other end side of the 3dB coupler are optically connected by an optical fiber loop 11 constituting an optical fiber loop mirror 9 and are closed. A part of the optical fiber loop 11 is composed of a rare earth added optical fiber 12 generating ASE light by using stimulation light of the stimulation light source device 8. Synthesized light of output ASE light is synthesized in the optical fiber loop 11 and is outputted from one port 10b between the first and second input/output ports, and is taken outside from an optical connection path 7 between the first ASE light source device 2 and the second ASE light source device 3 by an ASE light take-out device 4. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ASE light source, and more particularly, to an ASE light source capable of outputting broadband ASE.
[0002]
[Prior art]
In recent years, with the increase in communication capacity, wavelength division multiplexing (WDM: Wavelength Division Multiplexing) optical fiber communication systems for multiplexing and transmitting optical signals of different wavelengths within a single-core optical fiber have been actively studied. In WDM optical fiber transmission, the transmission capacity can be increased by increasing the number of optical signals of different wavelengths to be multiplex-transmitted in an optical fiber. Therefore, in wavelength-division multiplexed optical fiber communication, if transmission is possible in a wide wavelength band, the number of wavelengths of optical signals can be increased, leading to an increase in capacity. For these reasons, there is a demand for the development of a wideband optical fiber communication system and a wideband optical component for a WDM system used therefor.
[0003]
On the other hand, when pumping light is input to the amplification optical fiber, the energy level of the laser element added to the inside of the optical fiber is temporarily increased by exciting the amplification optical fiber, and the energy level becomes stable again. It is known that when returning to the above, light in the amplification band of the optical fiber is output by performing energy emission. This light is called spontaneous emission (ASE) light. The light source that outputs the ASE light is the ASE light source, which has a feature that it has a wide band and a high output.
[0004]
Therefore, ASE light sources have begun to be used as light sources for evaluation of loss wavelength characteristics, polarization mode dispersion, polarization dependent loss, etc. of optical components for WDM systems. However, since the bandwidth of the optical fiber communication system has been increasing day by day, an ASE light source having a wider bandwidth is desired.
[0005]
[Patent Document 1]
Patent No. 2756510 [Patent Document 2]
JP 2001-185790 A
[Problems to be solved by the invention]
As a method of manufacturing a broadband ASE light source, there is a change in a host glass and an additive of an optical fiber for optical amplification. The former is to change the host glass of the optical fiber for optical amplification as described in Patent Documents 1 and 2, that is, to use a fluoride glass, a tellurite glass, or the like instead of the conventional quartz glass. In the latter case, as described in Patent Document 2, the additive of the optical fiber for optical communication is changed, that is, erbium is added to generate ASE light in the C band (1530 nm to 1565 nm). To add another laser element to generate ASE light such as S band (1460 nm to 1530 nm) or L band (1565 nm to 1625 nm). Further, as a method of manufacturing an ASE light source having a wider band, there is a method of multiplexing ASE light with a wavelength-multiplexing multiplexer and manufacturing one ASE light source that outputs the multiplexed light.
[0007]
In a multi-wavelength wavelength-multiplexed optical device, input light in a plurality of wavelength bands from a plurality of optical fibers is multiplexed into a single-core optical fiber and multiplexed light is output. In some cases, there is a wavelength at which the light is not output or the output becomes unstable due to a change in environmental temperature or the like even if the light is output. Therefore, according to the above method, light is not output near the boundary wavelength of each wavelength band, or the output becomes unstable even if output. This indicates that accurate measurement cannot be performed near the boundary of the multiplexing in the evaluation of the loss of the optical components and the like, which is a disadvantage as a light source.
[0008]
Therefore, an object of the present invention is to provide an ASE light source having a stable output over a wide band and all bands in view of the above problem.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, an ASE light source according to the present invention includes a first ASE light source device, a second ASE light source device, and an ASE light extraction device. The first ASE light source device includes a 3 dB coupler provided with first and second input / output ports on one end and third and fourth input / output ports on the other end, respectively. An excitation light source device optically connected to one of the two input / output ports and an optical fiber loop mirror. The second ASE light source device has an output port optically connected to the other of the first and second input / output ports. The optical fiber loop mirror includes an optical fiber loop for optically connecting the third and fourth input / output boats in a closed state. At least a part of the optical fiber loop is composed of a rare earth-doped optical fiber. The rare-earth-doped optical fiber generates ASE light by spontaneous emission using excitation light of the excitation light source device input from one of the first and second input / output ports. The ASE light extraction device is a multiplexed light of the output ASE light of the first and second ASE light source devices that is multiplexed in the optical fiber loop and output from the other of the first and second input / output ports. From the optical connection path between the first ASE light source device and the second ASE light source device.
[0010]
The ASE light source of the present invention produces the following effects. The fiber loop mirror device provided with a 3 dB coupler has a characteristic that light input via the 3 dB coupler is output from the same input port of the 3 dB coupler as at the time of input. For this reason, in the present invention in which at least a part of the optical fiber loop constituting the optical fiber loop mirror is composed of the rare earth doped optical fiber, the ASE light input into the optical fiber loop mirror and the ASE light generated in the optical fiber loop mirror are generated. The ASE light is multiplexed in the optical fiber loop mirror and output from the 3 dB coupler. At that time, the ASE light input to the optical fiber loop mirror is only output from the optical fiber loop after being input to the optical fiber loop, so that no attenuation occurs in the entire band.
[0011]
Therefore, even if the ASE light generated as the first and second ASE light source devices is configured to be in contact with each other, the entire wavelength band of the ASE light output from the first and second ASE light source devices is attenuated. They can be multiplexed without causing multiplexing.
[0012]
In this case, it is preferable that the second ASE light source device is configured as follows. That is, the second ASE light source device combines the third and fourth ASE light source devices in which the bands of the generated ASE light are not in contact with each other and the output ASE light of the third and fourth ASE light source devices. It is preferable to have a wavelength-multiplexed wave device for outputting to the first ASE light source device.
[0013]
Then, the output ASE lights output from the third and fourth light source devices do not touch each other at their band ends. Therefore, even if these ASE lights are multiplexed by the wavelength division multiplexer, they are multiplexed. There is no band in which the effect of attenuation occurs in the later combined ASE light. Therefore, by combining such a second ASE light source device and the above-described first ASE light source device, ASE lights whose band ends are in contact with each other can be multiplexed without causing the influence of attenuation.
[0014]
Preferably, the ASE light extraction device is an optical circulator, so that the combined ASE light can be extracted from the ASE light source without attenuating. Moreover, at this time, the ASE light output from the second ASE light source device can be taken into the first ASE light source device without being attenuated.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
First, Embodiment 1 of the present invention will be described.
[0016]
The ASE light source 1 according to the first embodiment includes a first ASE light source device 2, a second ASE light source device 3, and an ASE light extraction device 4. The first ASE light source device 2 is a device that generates C band (1530 nm to 1565 nm) ASE light, and the second ASE light source device 3 is a device that generates S band (1460 nm to 1530 nm) ASE light. is there. In this way, the bands are arranged such that the band ends are in contact with each other.
[0017]
The first ASE light source device 2 includes an input / output port 5 which also serves as an input end and an output end of the ASE light. The second ASE light source device 3 includes an output port 6 for ASE light. The input / output port 5 and the output port 6 are optically connected by an optical connection path 7 composed of a communication optical fiber.
[0018]
The ASE light extraction device 4 includes an optical circulator. The ASE light extraction device 4 is provided in the middle of the optical connection path 7. The ASE light extraction device 4 has three input / output ports 4a, 4b, 4c. The input / output ports 4a to 4c have the following characteristics. Light input to the input / output port 4a is selectively output to the input / output port 4b. Light input to the input / output port 4b is selectively output to the input / output port 4c. Light input to the input / output port 4c is selectively output to the input / output port 4a.
[0019]
In the ASE light extraction device 4 having such characteristics, the input / output port 4 a is optically connected to the output port 6 of the second ASE light source device 3. The input / output port 4b is optically connected to the input / output port 5 of the first ASE light source device 2. The input / output port 4c functions as an output port of the ASE light source 1.
[0020]
The second ASE light source device 3 may have any configuration. For example, the second ASE light source device 3 includes an excitation light source device that generates excitation light in a band suitable for generating S-band ASE light, and a spontaneous emission using the excitation light generated by the excitation light source device. A rare earth-doped optical fiber for generating S-band ASE light.
[0021]
The first ASE light source device 2 has an excitation light source device 8, an optical fiber loop mirror 9, and a 3 dB coupler 10. The 3 dB coupler 10 has a first input / output port 10a and a second input / output port 10b on one end, and a third input / output port 10c and a fourth input / output port 10d on the other end. Is provided.
[0022]
The excitation light source device 8 generates excitation light in a band (for example, 0.98 μm or 1.48 μm) suitable for generating C-band ASE light. An output port 8a of the excitation light source device 8 is optically connected to a first input / output port 10a. The input / output port 5 of the first ASE light source device 2 is optically connected to the second input / output port 10b.
[0023]
The optical fiber loop mirror 9 has an optical fiber loop 11. Both ends of the optical fiber loop 11 are optically connected to a third input / output port 10c and a fourth input / output port 10d, respectively. The third input / output port 10c and the fourth input / output port 10d are optically connected while being closed by the optical fiber loop 11. The central portion of the optical fiber loop 11 is doped with a rare earth element (for example, erbium) suitable for C-band optical amplification, and forms a rare earth-doped optical fiber 12. The rare earth-doped optical fiber 12 generates C-band ASE light by spontaneous emission using the excitation light generated by the excitation light source device 8. In the middle of the optical fiber loop 11, a polarization controller (Polarization Controller) 13 is provided. The polarization controller 13 is provided to stabilize the output of the optical fiber loop 11. The polarization controller 13 is provided at a fiber portion of the optical fiber loop 11 other than the rare-earth-doped optical fiber 12.
[0024]
Next, an operation of generating ASE light by the ASE light source 1 will be described. First, in the second ASE light source device 3, S-band ASE light is generated. The S-band ASE light is output from the output port 6 and input to the input / output port 4a of the ASE light extraction device 4. The ASE light extraction device 4 outputs the ASE light input to the input / output port 4a from the input / output port 4b. The S-band ASE light output from the input / output port 4b of the ASE light extraction device 4 is input to the input / output port 5 of the first ASE light source device 2, and further input to the second input / output port 10b of the 3dB coupler 10. Is done. The S-band ASE light input to the second input / output port 10b is split and output from the third input / output port 10c and the fourth input / output port 10d due to the characteristics of the 3dB coupler 10. At this time, the demultiplexed output of the S-band ASE light is distributed by 50% for each output according to the characteristics of the 3 dB coupler 10, and is output from the third input / output port 10c and the fourth input / output port 10d. The split outputs of the S-band ASE light output from the third input / output port 10c and the fourth input / output port 10d are input to the optical fiber loop 11 from both ends of the optical fiber loop 11, respectively. Each split output is output from the end of the optical fiber loop 11 that is different from that at the time of input, after propagating through the optical fiber loop 11. The S-band ASE light output from the optical fiber loop 11 is input to the 3 dB coupler 10 from the third input / output port 10c or the fourth input / output port 10d different from the output time.
[0025]
The optical fiber loop mirror 9, which is optically connected so that the third and fourth input / output ports 10c and 10d at one end are closed by the optical fiber loop 11, receives the light input to the 3dB coupler 10 at the same port as when inputting. Has the characteristic of outputting from Therefore, the S-band ASE light input to the 3 dB coupler 10 again after circulating through the optical fiber loop 11 is output from the same second input / output port 10b as when input.
[0026]
At this time, the excitation light generated by the excitation light source device 8 is input to the 3 dB coupler 10 from the first input / output port 10a. The pump light input to the first input / output port 10a is split and output from the third input / output port 10c and the fourth input / output port 10d due to the characteristics of the 3 dB coupler 10. At this time, the demultiplexed output of the pump light is distributed by 50% for each output according to the characteristics of the 3 dB coupler 10, and is output from the third input / output port 10c and the fourth input / output port 10d. The split output of the pump light output from the third input / output port 10c and the fourth input / output port 10d is input to the optical fiber loop 11 from both ends of the optical fiber loop 11, respectively.
[0027]
Each split output of the pump light propagates through the rare-earth-doped optical fiber 12 in the optical fiber loop 11 to cause spontaneous emission by the rare earth. As a result, C band ASE light is generated in the rare earth doped optical fiber 12. In this case, the pumping light is supplied to the rare-earth-doped optical fiber 12 from both ends, and spontaneous emission based on bidirectional pumping occurs. As a result, ASE light is generated with high efficiency and about twice as large as that in unidirectional pumping.
[0028]
The C-band ASE light generated in the rare-earth-doped optical fiber 12 in this manner is radiated toward both ends of the rare-earth-doped optical fiber 12 and then from both ends of the rare-earth-doped optical fiber 12 together with the S-band ASE light. Is output.
[0029]
The C-band ASE light output from both ends of the rare-earth-doped optical fiber 12 together with the S-band ASE light is input to the 3 dB coupler 10 from the third input / output port 10c or the fourth input / output port 10d of the 3dB coupler 10. .
[0030]
As a characteristic of the 3 dB coupler 10, the ASE light of the C band input to the 3dB coupler 10 is split into 50% outputs and output from the first input / output port 10a and the second input / output port 10b. . At this time, the S-band ASE light is selectively output from the second input / output port 10b as described above. Therefore, of the ASE light of the C band output from the 3 dB coupler 10, the demultiplexed output output from the first input / output port 10a is not combined with the ASE light of the S band and is not coupled to the excitation light source device 8 side. Is output to On the other hand, the demultiplexed output output from the second input / output port 10b is input to the ASE light extraction device 4 in a state where it is combined with the S-band ASE light. At this time, almost 100% of the S band ASE light at the time of output from the second ASE light source device 3 is combined with the C band ASE light. At this time, the ASE light of the S band and the ASE light of the C band are multiplexed without any attenuation at the band edges even though their band edges are in contact with each other.
[0031]
The S-band ASE light and the C-band ASE light input to the input / output port 4b of the ASE light extraction device 4 in the multiplexed state in this way depend on the characteristics of the ASE light extraction device 4 (optical circulator). , Almost 100% of which is output from the input / output port 4c of the ASE light extraction device 4 to the outside.
[0032]
In the first embodiment described above, the first ASE light source device 2 generates C-band ASE light, and the second ASE light source device 3 generates S-band ASE light. However, the first ASE light source device 2 may generate S-band ASE light, and the second ASE light source device 3 may generate C-band ASE light. Alternatively, one ASE light source device may generate L-band ASE light, and the other ASE light source device may generate C-band ASE light. In short, the first ASE light source device 2 and the second ASE light source device 3 may individually generate the ASE light having the bands that are in contact with the band edges.
[0033]
Next, a second embodiment of the present invention will be described. The ASE light source 20 of this embodiment is characterized in that a second ASE light source device 21 is provided instead of the second ASE light source device 3 of the first embodiment. The other components are basically the same as in the first embodiment. Therefore, those components are denoted by the same reference numerals as in Embodiment 1 (FIG. 1), and detailed description will be omitted.
[0034]
The second ASE light source device 21 includes a third ASE light source device 22, a fourth ASE light source device 23, and a wavelength-multiplexed wave device 24.
[0035]
The third ASE light source device 22 is a device that generates ASE light in the S band (1465 nm to 1530 nm). The fourth ASE light source device 23 is a device that generates ASE light of the L band (1565 nm to 1625 nm). The wavelength-multiplexed wave device 24 is a device that wavelength-multiplexes the S-band ASE light generated by the third ASE light source device 22 and the L-band ASE light generated by the fourth ASE light source device 23. It is.
[0036]
As shown in FIG. 3, due to its characteristics, the wavelength-multiplexed wave filter 24 has a poor transmission band 25 having poor transmission characteristics at both ends of the wavelength in the S band region and outside both ends of the band in the L band region, as shown in FIG. Is inevitable.
[0037]
The S-band and the C-band or the C-band and the L-band, which are in contact with the band edge, can be considered to be in contact with each other by sharing the poor transmission band 25 in view of the transmission characteristics of the wavelength division multiplexer 24. The expression that the band ends of the ASE light are in contact with each other used in defining the present invention means that the poor transmission band 25 is shared and comes into contact with each other, and only the structure where the ends of both bands are in direct contact with each other. It does not indicate.
[0038]
On the other hand, the S band and the L band are wavelength bands separated from each other in band (S band: 1460 nm to 1530 nm, L band: 1565 nm to 1625 nm), and the poor transmission region 25 of one band is the other. Does not overlap with the poor transmission band 25 of the band.
[0039]
For such a reason, the S-band ASE light generated by the third ASE light source device 22 and the L-band ASE light generated by the fourth ASE light source device 23 are combined by the wavelength-multiplexed wave device 24. Even if the waves are waved, they can be combined without unnecessary attenuation of the ASE light of each band.
[0040]
Next, an operation of generating ASE light by the ASE light source 20 will be described. First, in the third ASE light source device 22 and the fourth ASE light source device 23, S-band ASE light and L-band ASE light are respectively generated. The generated S-band ASE light and L-band ASE light are optically multiplexed in the wavelength division multiplexer 24. At this time, the wavelength division multiplexer 24 optically multiplexes the ASE optical bands of both bands without any influence. Hereinafter, the combined light of the S-band ASE light and the L-band ASE light is referred to as S + L combined light.
[0041]
The S + L multiplexed light is output from the output port 6 of the second ASE light source device 21 and input to the input / output port 4a of the ASE light extraction device 4. The ASE light extraction device 4 outputs the S + L multiplexed light input to the input / output port 4a from the input / output port 4b. The S + L multiplexed light output from the input / output port 4b of the ASE light extraction device 4 is input to the input / output port 5 of the first ASE light source device 2, and further input to the second input / output port 10b of the 3dB coupler 10. . The S + L multiplexed light input to the second input / output port 10b is split and output from the third input / output port 10c and the fourth input / output port 10d due to the characteristics of the 3dB coupler 10. At this time, the demultiplexed output of the S + L multiplexed light is distributed by 50% for each output according to the characteristics of the 3 dB coupler 10, and is output from the third input / output port 10c and the fourth input / output port 10d. The demultiplexed outputs of the S + L multiplexed light output from the third input / output port 10c and the fourth input / output port 10d are input to the optical fiber loop 11 from both ends of the optical fiber loop 11, respectively. Then, after the respective demultiplexed outputs have propagated through the optical fiber loop 11, they are output from the end of the optical fiber loop 11 different from that at the time of input. The S + L multiplexed light output from the optical fiber loop 11 is input to the 3 dB coupler 10 from the third input / output port 10c or the fourth input / output port 10d different from the output time.
[0042]
The S + L multiplexed light input to the 3 dB coupler 10 again after circulating through the optical fiber loop 11 is output from the same second input / output port 10b as the input.
[0043]
At this time, in the rare-earth-doped optical fiber 12, as described in the first embodiment, spontaneous emission occurs using the excitation light supplied from the excitation light source device 8, and as a result, C-band ASE light is generated.
[0044]
The C-band ASE light generated in the rare-earth-doped optical fiber 12 in this manner is radiated toward both ends of the rare-earth-doped optical fiber 12 and then output from both ends of the rare-earth-doped optical fiber 12 together with the S + L multiplexed light. You.
[0045]
The C-band ASE light output from both ends of the rare-earth-doped optical fiber 12 together with the S + L multiplexed light is input to the 3 dB coupler 10 from the third input / output port 10c or the fourth input / output port 10d of the 3dB coupler 10.
[0046]
The C-band ASE light input to the 3 dB coupler 10 is split into 50% output and output to the first input / output port 10 a and the second input / output port 10 b as characteristics of the 3 dB coupler 10. At this time, the S + L multiplexed light is selectively output from the second input / output port 10b as described above. Therefore, of the C-band ASE light output from the 3 dB coupler 10, the demultiplexed output output from the first input / output port 10a is output to the pump light source device 8 side without being multiplexed with the S + L multiplexed light. Is done. On the other hand, the demultiplexed output output from the second input / output port 10b is input to the ASE light extraction device 4 in a state where it is multiplexed with the S + L multiplexed light. At this time, almost 100% of the S + L multiplexed light at the time of output from the second and third ASE light source devices 3 and 21 is multiplexed with the C-band ASE light, that is, S + L + C multiplexed light. Also, at this time, the S + L multiplexed light and the ASE light of the C band are multiplexed without any attenuation at the band edges even though their band edges are in contact with each other.
[0047]
In this multiplexed state, almost 100% of the S + L + C multiplexed light input to the input / output port 4b of the ASE light extraction device 4 is ASE light extraction due to the characteristics of the ASE light extraction device 4 (optical circulator). It is output to the outside from the input / output port 4c of the device 4.
[0048]
In the second embodiment described above, the S-band ASE light is generated by the third ASE light source device 22 and the L-band ASE light is generated by the fourth ASE light source device 23. Needless to say.
[0049]
The C-band ASE light and the L-band ASE light can be multiplexed by the wavelength-multiplexing multiplexer 22 with almost no unnecessary attenuation. Therefore, one of the third ASE light source device 22 and the fourth ASE light source device 23 generates C-band ASE light, and the other generates L-band ASE light. Then, the first ASE light source device 2 may be configured to generate S-band ASE light and combine it with C + L combined light.
[0050]
In each of the above-described embodiments, the ASE light extraction device 4 is configured by an optical circulator. However, the ASE light extraction device 4 may be configured by a 3 dB coupler, although the efficiency is slightly reduced.
[0051]
【The invention's effect】
As described above, according to the present invention, an ASE light source having a stable output over a wide band and the entire band can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of an ASE light source according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an ASE light source according to a second embodiment of the present invention.
FIG. 3 is a diagram showing transmission characteristics of a wavelength multiplexing wave device.
[Explanation of symbols]
Reference Signs List 1 ASE light source 2 First ASE light source device 3 Second ASE light source device 4 ASE light extraction device 4a, 4b, 4c Input / output port 5 Input / output port 6 Output port 7 Optical connection path 8 Excitation light source device 8a Excitation light output port Reference Signs List 9 optical fiber loop mirror 10 3dB coupler 10a first input / output port 10b second input / output port 10c third input / output port 10d fourth input / output port 11 optical fiber loop 12 rare earth doped optical fiber 20 ASE light source 21st 2 ASE light source device 22 3rd ASE light source device 23 4th ASE light source device 24 Wavelength multi-wavelength device 25 Transmission poor band

Claims (4)

A first ASE light source device, a second ASE light source device, and an ASE light extraction device;
The first ASE light source device includes a 3 dB coupler provided with first and second input / output ports on one end and third and fourth input / output ports on the other end, respectively. An excitation light source device optically connected to one of the two input / output ports, and an optical fiber loop mirror.
The second ASE light source device has an output port optically connected to the other of the first and second input / output ports,
The optical fiber loop mirror includes an optical fiber loop for optically connecting the third and fourth input / output boats in a closed state, and at least a part of the optical fiber loop is formed of a rare earth-doped optical fiber. The rare-earth-doped optical fiber generates ASE light by spontaneous emission using excitation light of the excitation light source device input from one of the first and second input / output ports,
The ASE light extraction device is a multiplexed light of the output ASE light of the first and second ASE light source devices that is multiplexed in the optical fiber loop and output from the other of the first and second input / output ports. From the optical connection path between the first ASE light source device and the second ASE light source device.
An ASE light source, characterized in that: The ASE light source according to claim 1,
In the first and second ASE light source devices, band ends of ASE light to be generated are in contact with each other.
An ASE light source, characterized in that: The ASE light source device according to claim 2,
The second ASE light source device includes:
Third and fourth ASE light source devices in which the band ends of the generated ASE light are not in contact with each other;
A wavelength multi-wavelength combiner that combines output ASE lights of the third and fourth ASE light source devices and outputs the multiplexed ASE light to the first ASE light source device;
An ASE light source comprising: The ASE light source device according to any one of claims 1 to 3,
The ASE light extraction device is an optical circulator,
An ASE light source, characterized in that:

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