CN113078535B - All-fiber structure switchable C/L waveband amplified spontaneous radiation light source system - Google Patents

Abstract

The invention discloses an all-fiber structure switchable C/L-band amplified spontaneous emission light source system, which is characterized in that it comprises a C-band generating device and an L-band generating device, and the pump light enters the C-band generating device or the L-band generating device through a first optical switch. The L-band generating device realizes C/L/C+L-band switching. The advantages are that the switching structure used in the present invention is simple, and compared with the current tunable ASE light source, the structure is simpler and the stability is strong, and the function of switching the wavelength band can be realized while reducing the cost.

Description

An all-fiber structure switchable C/L band amplified spontaneous emission light source system

technical field

The invention relates to the field of optical fiber communication technology and optical fiber sensing technology, in particular to a switchable L and C+L band amplified spontaneous emission (ASE) light source.

Background technique

In recent years, with the popularization of various communication products, the requirements for communication capacity have become higher and higher. Gradually, the previous C-band broadband light source has been unable to meet people's demand for bandwidth, and people immediately put their eyes on the C-band. longer L-band. At present, the leading idea of realizing broadband and ultra-wideband amplification is still the method of combining amplifiers in each band. In the study of erbium-doped fiber broadband ASE light sources with various structures, researchers found that without adding a gain flattening filter (GFF), the output spectrum of the C+L-band broadband ASE light source is mostly uneven. There is a peak around 1535nm, which is due to the properties of erbium ions. If this problem is not solved, the gain power difference between the peak of the output spectrum and other positions will be very large, which will seriously affect the overall available bandwidth and flatness of the output spectrum. Also in the field of ASE light source, the output power of C-band is often higher, and the power of C+L-band is lower, and the application field of L-band is constantly expanding. It will greatly improve the application field of ASE light source. Therefore, it is of great practical value to design a simple tuning device to tune the laser band between C, L, C+L bands.

SUMMARY OF THE INVENTION

Therefore, in order to realize the ASE light source that can switch between C, L, C+L bands without adding GFF, the present invention provides a novel switchable L, C+L band amplified spontaneous emission (ASE) light source. Based on the working principle of amplifying spontaneous radiation, mature commercial fiber amplifiers and the more commonly used single-mode fiber core pump structure are used, and the gain characteristics of erbium-doped fibers are used respectively. Er ³⁺ ions absorb the pump light to form a population inversion process, which in turn produces amplified spontaneous emission (ASE) light output. By adjusting the optical switch channel, the switching of the working band can be realized, and finally the ASE optical output with stable output power, good spectral flatness and switchable band can be realized. Its technical solution is,

An all-fiber structure switchable C/L-band amplified spontaneous emission light source system, comprising a C-band generating device and an L-band generating device, and pump light enters the C-band generating device or the L-band generating device through a first optical switch; the L-band generating device; The wave band generation device includes a first wavelength division multiplexer, an optical isolator and an optical circulator, and the pump light sequentially passes through the first wavelength division multiplexer, the first section of low erbium-doped fiber and the first fiber mirror, and then is converted by the first wave The demultiplexer enters the optical isolator and the optical circulator in turn. After being output by the optical circulator, it enters the second section of low-erbium-doped fiber and the second fiber mirror in turn. The second fiber mirror returns to the optical circulator, and the optical ring The C-band generating device includes a second wavelength division multiplexer, a third fiber mirror and a third section of low erbium-doped fiber, and the pump light sequentially passes through the second The wavelength division multiplexer, the third section of low erbium-doped fiber, and the third fiber reflection mirror enter the second wavelength division multiplexer from the third fiber reflection mirror and then enter the first fiber coupler to output C-band light.

Further, it also includes a second fiber coupler and a third fiber coupler, a second optical switch is arranged between the two, and the pump light enters the C-band generating device through the second fiber coupler, and enters the C-band generation device through the third fiber coupler. The L-band generating device; the pump light realizes switching among the L-band light, the C-band light, and the C+L-band light through the first optical switch and the second optical switch.

Further, generating the L-band light includes the following steps:

S1. The pump light is generated by a laser diode, and the pump light enters the third fiber coupler through the first optical switch, and then enters the first wavelength division multiplexer, the first section of low erbium-doped fiber and the third fiber coupler in turn. an optical fiber reflector, which enters the optical isolator through the first wavelength division multiplexer from the first fiber reflector;

The S2.C-band light enters the optical circulator through the optical isolator, and after being output by the optical circulator, enters the second section of low erbium-doped fiber and the second optical fiber reflector in turn, and enters the optical circulator from the second fiber reflector;

S3. The L-band light enters the first fiber coupler through the optical circulator, and the L-band light is output from the first fiber coupler.

Further, generating the C-band light includes the following steps:

S1. The pump light is generated by a laser diode, and the pump light enters the second fiber coupler through the first optical switch, and is selected by the second optical switch to enter the second wavelength division multiplexer, the third section of low erbium-doped fiber and the second optical fiber in turn. Three fiber optic mirrors, the third fiber optic mirror passes through the second wavelength division multiplexer;

S2.C-band light enters the first fiber coupler through the second wavelength division multiplexer, and outputs C-band light.

Further, generating C+L band light includes the following steps:

S1. The pump light is generated by a laser diode, and the pump light enters the second fiber coupler and the third fiber coupler simultaneously through the first optical switch;

S2. Part of the pump light from the second fiber coupler enters the third fiber coupler through the second optical switch, and the other part enters the second wavelength division multiplexer; the third fiber coupler sequentially enters the first wavelength division multiplexer , The first section of low erbium-doped fiber and the first fiber reflector, the first fiber reflector enters the optical isolator through the first wavelength division multiplexer, the C-band light enters the optical circulator through the optical isolator, and the optical circulator After output, it enters the second section of low-doped erbium fiber and the second fiber mirror in turn, and the second fiber mirror enters the optical circulator; at the same time, the pump light output from the second wavelength division multiplexer passes through the third section of low-doped fiber in turn. The erbium fiber and the third fiber reflector are output by the third fiber reflector through the second wavelength division multiplexer;

S3. The light from the optical circulator and the light from the second wavelength division multiplexer are coupled by the first fiber coupler to output C+L segment light.

Further, the switching method of the C-band and L-band ASE light output light is:

The pump light is switched on by the first light switch, and the second light switch is always turned off. The first light switch determines whether the pump light first passes through the L-band generating device or the C-band generating device;

When passing through the L-band generating device first, no pump light is injected into the C-band generating device, so the output light is L-band ASE light;

When passing through the C-band generating device first, the pump light is injected into the C-band generating device, and the L-band generating device has no pump light injection to realize the ASE light output in the C-band, thereby realizing the switching of the C-band and L-band ASE light output light.

Further, the switching method of the C+L-band and L-band ASE light output light is:

The pump light is switched through the first optical switch, and the first optical switch determines whether the pump light first passes through the second fiber coupler or the third fiber coupler;

When passing through the third fiber coupler first, it bypasses the second fiber coupler, so that no pump light is injected into the second part, so the output light is L-band ASE light;

When passing through the second fiber coupler first, the pump light is divided into two paths. At this time, the second light is turned on, and one path pumps the L-band generating device and the other pumping the C-band generating device, and finally the first fiber couples. The output is coupled at the device to realize the ASE light output in the C+L band, so as to realize the switching of the ASE light output light in the L and C+L bands.

The switching method of C+L-band and C-band ASE light output light is:

The pump light path enters the second fiber coupler through the first optical switch, and is switched by the second optical switch. The second optical switch determines whether the pump light passes through the third fiber coupler and the second wavelength division multiplexer at the same time or not. Enter the second wavelength division multiplexer alone;

Enter the third fiber coupler and the second wavelength division multiplexer at the same time to realize the C+L-band ASE optical output; enter the second wavelength division multiplexer alone to realize the C-band ASE optical output, so as to achieve C and C+ Switching of L-band ASE optical output light

Further, the amplified spontaneous emission light source system is an all-fiber structure, which can switch C/L/C+L bands.

beneficial effect

Compared with the prior art, the beneficial effects of the present invention are:

1) Using the method of band combination, the LD pump optical path is changed by optical switching, so that a single LD can generate C and L band light, and then select the output optical band. And without adding a gain flattening filter, its spectral flatness is high;

2) The switching structure used in the present invention is simple, and compared with the current tunable ASE light source, the structure is simpler and the stability is strong, and the function of switching the wavelength band can be realized while reducing the cost.

3) The present invention uses an all-fiber structure, which is stable in structure and is not easily disturbed by the external environment, and uses a fiber mirror to reflect the ASE light for secondary amplification, thereby improving the pumping efficiency.

Description of drawings

Figure 1 is a schematic diagram of the C, L, C+L band switchable ASE light source system;

Figure 2 is the output L-band spectrogram;

Figure 3 is the output C+L band spectrogram;

Figure 4 is a schematic diagram of a C and L band switchable ASE light source system;

1. The first optical fiber mirror (OFR) 2, the first low-doped erbium fiber (EDF) 3, the first wavelength division multiplexer (WDM) 4, the optical isolator (ISO) 5, the second low-doped fiber Erbium fiber 6, second fiber reflector (OFR) 7, optical circulator (OC) 8, 1 × 2 first fiber coupler 9, third fiber reflector (OFR) 10, third segment of low erbium-doped fiber ( EDF) 11, second wavelength division multiplexer (WDM) 12, first 1×2 optical switch (Optical Switch) 13, 976nm laser diode (LD) 14, second 1×2 fiber coupler 15, third 1 ×2 fiber couplers; 16. The second optical switch.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. Preferred embodiments of the invention are shown in the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided so that a thorough and complete understanding of the present disclosure will be provided.

The structure of the ASE light source provided in this example based on L, C or C+L band switching based on optical switch regulation is shown in Figure 1, which includes three parts: the first part is the L-band generating device, which consists of a first fiber mirror 1, a first Section LED 2, first wavelength division multiplexer (980/1550) 3, optical isolator 4, second section LED 5, second fiber mirror 6, optical circulator 7, first 1 × 2 fiber couplers are composed of 8. The second part is the C-band generation device, which consists of a third fiber mirror 9, a third section of low erbium-doped fiber 10, and a second wavelength division multiplexer 11. The third part is a pump light and band switching device, consisting of The first 1×2 optical switch 12 , the 976 nm laser diode 13 , the second 1×2 optical fiber coupler 14 , the third 1×2 optical fiber coupler 15 , and the second optical switch 16 are composed.

The pump light includes a 976 nm laser diode and a pigtail, the center wavelength of the 976 nm laser diode is 976 nm, is single-mode pumping, and the average power is greater than 300 mW, and the pigtail is a single-mode fiber.

The split ratios of the first 1×2 fiber coupler 8 , the second 1×2 fiber coupler 14 , and the third 1×2 fiber coupler 15 are all 50:50, and are highly transparent to the S+C+L band.

The models of the first wavelength division multiplexer 3 and the second wavelength division multiplexer 11 are both 976/1550. The first wavelength division multiplexer and the second wavelength division multiplexer have two output ends, and three end ends. fiber, in which the pigtail is a single-mode fiber, one end is 1550 end, and one end is 976 end.

The first section of low erbium doped fiber 2 and the second section of low erbium doped fiber 5 are MP980 fibers from OFS, whose core and cladding are 7 μm/125 μm respectively, and are reflected by the first fiber mirror 1 and the second fiber. The mirror 7 significantly improves the secondary absorption efficiency of the L-band and shortens the length of the EDF used.

The length of the first low erbium-doped fiber (EDF) described in this embodiment is 13.3 m, and the absorption rate at 976 nm is 6 dB/m.

The length of the second EDF described in this embodiment is 90 m, and the absorption rate at 976 nm is 6 dB/m.

The third EDF described in this example has a length of 7.5 m and an absorption rate of 6 dB/m at 976 nm.

The center wavelength of the first fiber optic mirror and the second fiber optic mirror described in this embodiment is 1570 nm, the bandwidth is 100 nm, and the transmittance is ≥90%.

The optical fiber circulator 8 described in this embodiment has a center wavelength of 1580 nm and is highly transparent in the S+C+L band.

When the optical switch described in this embodiment is turned off, its transmittance is -30 dB.

Generating L-band light includes the following steps:

S1. The pump light is generated by the 976 nm laser diode 13, and the pump light enters the third 1×2 fiber coupler 15 through the first 1×2 optical switch 12. At this time, the second optical switch 16 is turned off, and the light is transmitted by the third 1×2 optical switch 12. The ×2 fiber coupler 15 sequentially enters the first wavelength division multiplexer 3, the first section of low-Erbium-doped fiber 2 and the first fiber mirror 1, and is reflected by the first fiber-optic mirror 1 and then passes through the first section of low-Erbium-doped fiber Optical fiber 2, then enters optical isolator 4 through first wavelength division multiplexer 3;

The S2.C-band light enters the optical circulator 7 through the optical isolator 4, and after being output by the optical circulator 7, enters the second section of the low-erbium-doped fiber 5 and the second fiber reflection mirror 6 in turn, and the second fiber reflection mirror 6 again Enter the optical circulator 7;

S3. The L-band light enters the first 1×2 fiber coupler 8 through the optical circulator 7 , and the L-band light is output from the first 1×2 fiber coupler 8 .

Generating C-band light includes the following steps:

S1. The pump light is generated by the laser diode 13, and the pump light enters the second 1×2 fiber coupler 14 through the first 1×2 optical switch 12. At this time, the second optical switch 16 is turned off, and the light is transmitted by the second 1×2 optical switch 12. The fiber coupler 14 and the second optical switch 16 sequentially enter the second wavelength division multiplexer 11, the third section of the low erbium-doped fiber 10 and the third fiber mirror 9, and the third fiber mirror 9 passes through the second wavelength division multiplexer. user 11;

The S2.C-band light enters the first 1×2 fiber coupler 8 through the second wavelength division multiplexer 11, and outputs the C-band light.

Generating C+L band light includes the following steps:

S1. The pump light is generated by the laser diode 13, and the pump light enters the second 1×2 fiber coupler 14 and the third 1×2 fiber coupler 15 simultaneously through the first 1×2 optical switch 12. At this time, the second light switch 16 is open;

S2. Part of the pump light from the second optical fiber coupler 14 enters the third optical fiber coupler 15 through the second optical switch 16, and the other part enters the second wavelength division multiplexer 11; The wavelength division multiplexer 3, the first section of the low erbium-doped fiber 2 and the first fiber reflection mirror 1, the first fiber reflection mirror 1 enters the optical isolator 4 through the first wavelength division multiplexer 3, and the C-band light passes through the optical isolator 4. The isolator 4 enters the optical circulator 7, and after being output by the optical circulator 7, it enters the second section of the low erbium-doped fiber 5 and the second fiber mirror 6 in turn, and the second fiber mirror 6 enters the optical circulator 7; The C-band light output by the second wavelength division multiplexer 11 sequentially passes through the third segment of the low erbium-doped fiber 10 and the third fiber reflection mirror 9, and is output by the third fiber reflection mirror 9 through the second wavelength division multiplexer 11;

S3. The light from the optical circulator 7 and the light from the second wavelength division multiplexer 11 are coupled by the first 1×2 fiber coupler 8 to output the C+L segment light.

Embodiment 1, realize the switching method of L and C+L band as follows:

The pump beam emitted by the pump light in this embodiment enters the first section of the low-erbium-doped fiber and the second section of the low-erbium-doped fiber in the first part through the first wavelength division multiplexer for pumping to form L Band output.

The pump beam emitted by the pump light in this embodiment enters the first low erbium-doped fiber through the first wavelength division multiplexer and the second wavelength division multiplexer of the second part, respectively, and the third low erbium-doped fiber. The erbium-doped fiber is pumped to form the output in the C+L band.

In the third part, the pump light path is switched by the first optical switch 12 . The first optical switch 12 determines whether the pump light first passes through the second 1×2 fiber coupler 14 or the third 1×2 fiber coupler 15 . When passing through the third 1×2 fiber coupler 15 first, it bypasses the second 1×2 fiber coupler 14 , so that no pump light is injected in the second part, so the output light is L-band ASE light. When passing through the second 1×2 fiber coupler 14 first, the pump light is divided into two paths. At this time, the second light switch 16 is turned on, one path pumps the L-band generation device, and the other path pumps the C-band generation device, and finally The output is coupled at the first 1×2 fiber coupler 8 to realize the output of the ASE light in the C+L band, so as to achieve the effect of switching the output light of the ASE light in the L and C+L bands.

Embodiment 2, realize the switching of L and C band, the method is as follows:

The pump beam emitted by the pump light in this embodiment enters the first section of the low-erbium-doped fiber and the second section of the low-erbium-doped fiber in the first part through the first wavelength division multiplexer for pumping to form L Band output.

The pump beam emitted by the pump light described in this embodiment enters the first section of the low erbium-doped fiber through the second wavelength division multiplexer in the second part for pumping to form the C-band output.

The length of the first erbium-doped fiber EDFL described in this embodiment is 13.3 m, and the absorption rate at 976 nm is 6 dB/m.

The length of the second erbium-doped fiber EDFL described in this embodiment is 90 m, and the absorption rate at 976 nm is 6 dB/m.

The length of the third erbium-doped fiber EDFL described in this embodiment is 7.5 m, and the absorption rate at 976 nm is 6 dB/m.

The optical fiber mirror described in this embodiment has a center wavelength of 1570 nm, a bandwidth of 100 nm, and a transmittance of ≥90%.

The optical fiber circulator described in this embodiment has a center wavelength of 1580 nm and is highly transparent in the S+C+L band.

When the optical switch described in this embodiment is turned off, its transmittance is -30 dB.

In the third part, the pump light path is switched by the first 1×2 optical switch 12, and the second optical switch 16 is always turned off. The first 1×2 optical switch 12 determines whether the pump light first passes through the L-band generator or the C-band generator. Band generation device. When passing through the L-band generating device first, no pump light is injected into the C-band generating device, so the output light is L-band ASE light. When passing through the C-band generating device first, the pump light is injected into the C-band generating device, and the L-band generating device is not injected with pump light, so as to realize the ASE light output in the C-band. So as to achieve the effect of switching C and L band ASE light output light.

Embodiment 3 realizes the switching method of C and C+L band as follows:

The pump light path enters the second 1×2 fiber coupler 14 through the first 1×2 optical switch 12, and is switched by the second optical switch 16. The second optical switch 16 determines that the pump light passes through the third 1× 2 fiber coupler 15 and second wavelength division multiplexer 11. Enter the third 1×2 optical fiber coupler 15 and the second wavelength division multiplexer 11 at the same time to realize the ASE light output of the C+L band, enter the second wavelength division multiplexer 11 separately, and pass through the C band generation device to realize the C band. ASE light output, so as to achieve the effect of switching the C and C+L band ASE light output light.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included within the protection scope of this application.

Claims (7)

1. A full-optical-fiber-structure switchable C/L waveband amplified spontaneous emission light source system is characterized by comprising a C waveband generating device and an L waveband generating device, wherein pumping light enters the C waveband generating device or the L waveband generating device through a first optical switch; the L-band generating device comprises a first wavelength division multiplexer, an optical isolator and an optical circulator, pump light sequentially passes through the first wavelength division multiplexer, a first section of low erbium-doped optical fiber and a first optical fiber reflector, then sequentially enters the optical isolator and the optical circulator through the first wavelength division multiplexer, is output by the optical circulator, sequentially enters a second section of low erbium-doped optical fiber and a second optical fiber reflector, returns to the optical circulator through the second optical fiber reflector, and is output to the first optical fiber coupler through the optical circulator to output L-band light; the C-band generating device comprises a second wavelength division multiplexer, a third optical fiber reflector and a third section of low erbium-doped optical fiber, and pump light sequentially passes through the second wavelength division multiplexer, the third section of low erbium-doped optical fiber and the third optical fiber reflector, enters the second wavelength division multiplexer from the third optical fiber reflector, then enters the first optical fiber coupler and outputs C-band light;

the pump light enters the C-band generating device through the second optical fiber coupler and enters the L-band generating device through the third optical fiber coupler; the pump light realizes the switching among the L-waveband light, the C-waveband light and the C + L-waveband light through the first optical switch and the second optical switch.

2. The switchable C/L band amplified spontaneous emission light source system of claim 1, wherein the generating of the L band light comprises the following steps:

s1, pump light is generated by a laser diode, enters a third optical fiber coupler through a first optical switch, sequentially enters a first wavelength division multiplexer, a first section of low erbium-doped optical fiber and a first optical fiber reflector through the third optical fiber coupler, and enters an optical isolator through the first wavelength division multiplexer through the first optical fiber reflector;

s2.C waveband light enters the optical circulator through the optical isolator, is output by the optical circulator, sequentially enters the second section of low erbium-doped optical fiber and the second optical fiber reflector, and enters the optical circulator through the second optical fiber reflector;

and S3, the L-band light enters the first optical fiber coupler through the optical circulator, and the first optical fiber coupler outputs the L-band light.

3. The switchable C/L band amplified spontaneous emission light source system of claim 1, wherein the generating of the C band light comprises the following steps:

s1, pump light is generated by a laser diode, enters a second optical fiber coupler through a first optical switch, and enters a second wavelength division multiplexer, a third section of low erbium-doped optical fiber and a third optical fiber reflector in sequence through selection of the second optical switch, and passes through the second wavelength division multiplexer by the third optical fiber reflector;

and S2, the C-band light enters the first optical fiber coupler through the second wavelength division multiplexer and is output.

4. The switchable C/L band amplified spontaneous emission light source system of claim 1, wherein the generation of C + L band light comprises the following steps:

s1, pump light is generated by a laser diode and enters a second optical fiber coupler and a third optical fiber coupler simultaneously through a first optical switch;

s2, pumping light passes through a second optical fiber coupler, one part of the pumping light passes through a second optical switch to enter a third optical fiber coupler, and the other part of the pumping light enters a second wavelength division multiplexer; the light of C wave band enters the optical circulator through the optical isolator, and after being output by the optical circulator, the light enters the second section of low erbium-doped optical fiber and the second optical fiber reflector in sequence, and enters the optical circulator through the second optical fiber reflector; meanwhile, the pump light output by the second wavelength division multiplexer sequentially passes through the third section of low erbium-doped fiber and the third fiber reflector, and is output by the third fiber reflector through the second wavelength division multiplexer;

and S3, coupling the light from the optical circulator and the light from the second wavelength division multiplexer through the first optical fiber coupler and then outputting C + L section light.

5. The switchable C/L band spontaneous emission light source system of claim 1, wherein the pump light is switched by a first light switch, and the second light switch is always turned off, and the first light switch determines whether the pump light first passes through the L band generating device or the C band generating device;

when the light passes through the L-band generating device, no pumping light is injected into the C-band generating device, so that the output light is L-band ASE light;

when the pump light passes through the C-band generation device, the pump light is injected into the C-band generation device, the L-band generation device is not injected with the pump light, the ASE light output of the C-band is realized, and the switching of the output light of the ASE light of the C, L bands is realized.

6. The switchable C/L band spontaneous emission light source system of claim 1, wherein the pump light is switched by a first optical switch, and the first optical switch determines whether the pump light first passes through the second fiber coupler or the third fiber coupler;

when the light passes through the third optical fiber coupler, the light bypasses the second optical fiber coupler, so that no pump light is injected into the second part, and the output light is L-waveband ASE light;

when the pumping light passes through the second optical fiber coupler, the pumping light is divided into two paths, at the moment, the second light is switched on, one path of pumping L-waveband generating device and the other path of pumping C-waveband generating device are finally coupled and output at the first optical fiber coupler, the output of ASE light of C + L waveband is realized, and the switching of the output light of the ASE light of L and C + L wavebands is realized.

7. The switchable C/L band amplified spontaneous emission light source system of claim 1, wherein the pump light path enters the second fiber coupler through the first optical switch and is switched by the second optical switch, and the second optical switch determines whether the pump light simultaneously passes through the third fiber coupler and the second wavelength division multiplexer or enters the second wavelength division multiplexer separately;

simultaneously enters a third optical fiber coupler and a second wavelength division multiplexer to realize ASE optical output of C + L wave band; and the light enters the second wavelength division multiplexer independently to realize the output of the ASE light of the C waveband, so that the switching of the output light of the ASE light of the C and C + L wavebands is realized.

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