A fiber optical amplifier

Abstract

The present invention provides a fiber optic amplifier, comprising an optical circulator having at least four ports, wherein the first port of the optical circulator receives signal light; and an optical composite component having a first pump light port, a second pump light port, a first signal light port, and a second signal light port. The first pump light port receives the first pump light, a first erbium-doped fiber is connected between the first signal light port and the second port of the optical circulator, a second erbium-doped fiber is connected between the second signal light port and the third port of the optical circulator, and the second pump light port receives the second pump light. The optical composite component comprises a filter and a reflector. The filter reflects the first pump light to the first signal light port, the filter also reflects the second pump light to the second signal light port, and the reflector reflects the incident signal light back along its original path. The present invention can reduce the length of the erbium-doped fiber used and reduce the volume of the fiber optic amplifier.

Description

Technical Field

[0001] The present invention relates to a fiber optic amplifier, in particular to an erbium-doped fiber amplifier with two-stage amplification or an erbium-doped fiber amplifier that mixes single-stage amplification and two-stage amplification. Background Art

[0002] Erbium Doped Fiber Application Amplifier (EDFA) is an important optical device in optical fiber systems and is a common optical device for amplifying the optical power of signal light.

[0003] Existing erbium-doped fiber amplifiers (EDFAs) can receive both signal light and pump light, boosting the signal light's optical power by simultaneously channeling the pump and signal light into a single optical fiber. The signal light's optical power amplification factor is related to the length of the EDFA. To increase signal light power amplification, longer EDFAs are often used, which increases the size and production cost of the EDFA.

[0004] Chinese invention patent application publication number CN115579725A discloses a MOPA laser system, which is equipped with a seed light source, a pump source, an isolator, a circulator, a combiner, a gain fiber, a wavelength division multiplexer, and a first reflector and a second reflector. The signal light of the system can pass through the gain fiber twice to increase the optical power of the signal light.

[0005] However, because the signal and pump light are combined in a beam combiner before passing through the gain fiber, a wavelength division multiplexer (WDM) is required in the subsequent stage to separate the combined optical signal into signal and pump light, and two reflectors are required to reflect the signal and pump light, respectively. This system uses many optical components, especially the WDM and the first and second reflectors, which makes the entire laser system more complex. Furthermore, an optical circulator is also required, which hinders the miniaturization of the laser system and increases production costs.

[0006] On the other hand, since the system only performs one-stage amplification on the signal light, that is, the signal light and the pump light are coupled only once, when the optical power of the initially incident signal light is low, amplifying the signal light only once is often not enough to meet the needs of the subsequent stage. Sometimes, the signal light after the first stage amplification needs to be amplified again, that is, two-stage amplification is required.

[0007] The current approach is to design a two-stage parallel erbium-doped fiber amplifier, for example, using two of the above-mentioned laser systems, and inputting the optical signal output by the first-stage laser system into the second-stage laser system. However, this approach will result in the use of more components in the optical system, a larger volume, and higher production costs. Summary of the Invention

[0008] The object of the present invention is to provide a fiber optic amplifier which is small in size and low in production cost and can perform secondary amplification on signal light.

[0009] In order to achieve the above-mentioned objectives, the present invention provides a fiber optic amplifier including an optical circulator, which has at least four ports, and the first port of the optical circulator receives signal light; and the fiber optic amplifier also includes an optical composite device assembly, which has a first pump light port, a second pump light port, a first signal light port and a second signal light port, the first pump light port receives the first pump light, a first erbium-doped fiber is connected between the first signal light port and the second port of the optical circulator, a second erbium-doped fiber is connected between the second signal light port and the third port of the optical circulator, and the second pump light port receives the second pump light; the optical composite device assembly has a filter and a reflector, the filter reflects the first pump light to the first signal light port, the filter also reflects the second pump light to the second signal light port, and the reflector reflects the incident signal light along the original path.

[0010] As can be seen from the above scheme, the signal light incident from the first signal light port is coupled with the first pump light incident from the first pump light port, achieving a first-stage amplification of the signal light's optical power. After passing through the optical circulator and the first erbium-doped fiber, the signal light, after the first stage of amplification, can be incident on the second signal light port, where it is again coupled with the second pump light. After passing through the second erbium-doped fiber, the signal light can be amplified to a second stage of optical power. The amplified signal light can then be emitted from the fourth port of the optical circulator.

[0011] A preferred solution is that the optical composite device assembly is a four-port optical hybrid device, which is provided with a filter, a polarization state rotator and a reflector. The first pump light and the second pump light are both reflected by the filter, and the signal light incident from the first signal light port and the second signal light port is both reflected by the reflector. After the signal light passes through the polarization state rotator twice, the polarization direction of the signal light is rotated by 90°.

[0012] It can be seen that using a four-port optical hybrid device as an integrated optical composite device component can miniaturize the structure of the optical composite device component, thereby making the structure of the entire fiber optical amplifier very compact, meeting the product layout requirements in a small space and having a wider range of application scenarios.

[0013] A further solution is that the four-port optical hybrid device also includes a four-wire pigtail, in which two pump optical fibers and two signal optical fibers are arranged; a collimating lens is arranged at one end of the four-wire pigtail, a filter is arranged at the end of the four-wire pigtail away from the collimating lens, and a reflector is arranged at the end of the filter away from the collimating lens.

[0014] As can be seen, the filter reflects the first and second pump lights of specific wavelengths, coupling the first pump light with the signal light incident from the first signal light port, and the second pump light with the signal light incident from the second signal light port. This reflective design allows the signal light to pass through the erbium-doped fiber twice. For the same optical power amplification factor, the length of the erbium-doped fiber can be reduced by half, thereby reducing the size and production cost of the fiber optical amplifier.

[0015] A further solution is that a polarization state rotation device is further provided between the filter and the reflector, and the polarization direction of the signal light is rotated by 45 degrees along the same rotation direction each time the signal light passes through the polarization state rotation device.

[0016] It can be seen from this that after the signal light passes through a polarization rotation device such as a Faraday rotator twice, the polarization direction will be rotated 90°, that is, the polarization states of the incident signal light and the outgoing signal light are perpendicular to each other, which can effectively avoid interference caused by the birefringence effect.

[0017] A further solution is that the optical composite device assembly includes a first two-port optical hybrid device and a second two-port optical hybrid device, the first pump light port and the first signal light port are arranged in the first two-port optical hybrid device, and the second pump light port and the second signal light port are arranged in the second two-port optical hybrid device.

[0018] It can be seen that by providing two independent two-port optical hybrid devices, mutual interference between signal lights incident from two signal light ports can be avoided, thereby improving the working stability of the fiber optical amplifier.

[0019] A further solution is that the first two-port optical hybrid device further includes a first filter and a first reflector sequentially arranged along the optical path; the second two-port optical hybrid device further includes a second filter and a second reflector sequentially arranged along the optical path.

[0020] It can be seen that each two-port optical hybrid device is equipped with independent filters, polarization rotators, and reflectors. Corresponding filters can be set for pump lights of different wavelengths, thereby improving the filtering effect of the pump light, better coupling effect between the pump light and the signal light, and better increasing the optical power of the signal light.

[0021] A further solution is that the first port of the optical circulator is connected to a first light splitting and photoelectric detection hybrid device; and / or the fourth port of the optical circulator is connected to a second light splitting and photoelectric detection hybrid device.

[0022] It can be seen that by connecting the splitter and photoelectric detection hybrid devices at both ends of the optical circulator, the optical power of the incident signal light can be detected, and the optical power of the signal light after optical power amplification can be detected to monitor the optical power amplification of the signal light.

[0023] A further solution is that a first splitting and photoelectric detection hybrid module and a second splitting and photoelectric detection hybrid module are provided in the optical circulator, the first splitting and photoelectric detection hybrid module is connected to the signal light incident port of the optical circulator, and the second splitting and photoelectric detection hybrid module is connected to the signal light output port of the optical circulator.

[0024] It can be seen that integrating the splitting and photoelectric detection hybrid devices in the optical circulator can meet the needs of optical power monitoring and at the same time make the structure of the fiber optical amplifier more compact, which is conducive to the miniaturization of the fiber optical amplifier.

[0025] A further solution is that the optical circulator includes a four-port optical ring module and a three-port optical ring module, and the optical composite device assembly is connected to the second port and the third port of the four-port optical ring module.

[0026] It can be seen that the two independently working optical ring modules are respectively provided in the optical circulator, which can meet the requirements of the first-level amplification and the second-level amplification of the signal light.

[0027] A further solution is that the first port of the three-port optical ring module receives the signal light, and the second port of the three-port optical ring module is connected to a third two-port optical hybrid device through a third section of erbium-doped optical fiber. The third two-port optical hybrid device includes a third filter and a third reflector arranged in sequence along the optical path. The third filter reflects the pump light incident from one port of the third two-port optical hybrid device to the signal light port, and the reflector reflects the incident signal light along the original path.

[0028] As can be seen, the three-port optical ring module is connected to the third two-port optical hybrid device, which couples the incident signal light with the pump light, thus achieving a single-stage amplification of the signal light. In this way, the fiber optical amplifier can amplify the signal light in either a single or two-stage manner, allowing users to flexibly select the signal light amplification factor as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FIG. 1 is a structural diagram of a first embodiment of a fiber optical amplifier according to the present invention.

[0030] Figure 2 FIG. 1 is a structural diagram of an optical composite device assembly in a first embodiment of a fiber optic amplifier according to the present invention.

[0031] Figure 3 FIG. 1 is a structural diagram of a two-port optical hybrid device in the first embodiment of the fiber optical amplifier of the present invention.

[0032] Figure 4 FIG. 1 is a structural diagram of a second embodiment of a fiber optical amplifier according to the present invention.

[0033] Figure 5 FIG. 1 is a structural diagram of a third embodiment of a fiber optical amplifier according to the present invention.

[0034] Figure 6 FIG. 4 is a structural diagram of a fourth embodiment of a fiber optical amplifier according to the present invention.

[0035] Figure 7 FIG. 1 is a structural diagram of a fifth embodiment of a fiber optical amplifier according to the present invention.

[0036] Figure 8 FIG. 1 is a structural diagram of a sixth embodiment of a fiber optical amplifier according to the present invention.

[0037] Figure 9 FIG. 1 is a structural diagram of a seventh embodiment of a fiber optical amplifier according to the present invention.

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0039] The fiber optic amplifier of the present invention has erbium-doped optical fiber, so it can be an erbium-doped optical fiber amplifier. The fiber optic amplifier has an optical circulator, which can achieve two-stage amplification of the optical power of the incident signal light, or optionally one-stage amplification. The length of the erbium-doped optical fiber used in the fiber optic amplifier is relatively short, which is conducive to the miniaturization of the fiber optic amplifier.

[0040] First embodiment:

[0041] See also Figure 1 This embodiment has an optical circulator 150 and an optical composite device assembly 110 . The optical composite device assembly 110 is a four-port optical hybrid device. In addition, the fiber optical amplifier further includes a two-port optical hybrid device 160 .

[0042] The optical circulator 150 of this embodiment integrates a four-port optical ring module and a three-port optical ring module. The four-port optical ring module and the three-port optical ring module operate independently and can share some internal optical components. The four-port optical ring module has four ports: a first port 151, a second port 152, a third port 153, and a fourth port 154. Optical signals within the four-port optical ring module can only be transmitted in one direction. That is, an optical signal incident from the first port 151 can only be emitted from the second port 152, an optical signal incident from the second port 152 can only be emitted from the third port 153, and an optical signal incident from the third port 153 can only be emitted from the fourth port 154.

[0043] The optical composite device assembly 110 of this embodiment also has four ports: a first pump light port 111, a second pump light port 114, a first signal light port 112, and a second signal light port 113. The first pump light port 111 is connected to a first pump light source 135 via an optical fiber and receives the first pump light emitted by the first pump light source 135. The second pump light port 114 is connected to a second pump light source 137 via an optical fiber and receives the second pump light emitted by the second pump light source 137. Preferably, the wavelength of the first pump light generated by the first pump light source 135 and the wavelength of the second pump light generated by the second pump light source 137 are the same. Of course, the wavelength of the first pump light may also be different from the wavelength of the second pump light. For example, the wavelength of the first pump light may be 980 nm, while the wavelength of the second pump light may be 1480 nm.

[0044] A first erbium-doped fiber 136 is connected between the first signal light port 112 and the second port 152 of the four-port optical ring module of the optical circulator 150, and a second erbium-doped fiber 138 is connected between the second signal light port 113 and the third port 153 of the four-port optical ring module of the optical circulator 150. Preferably, the first erbium-doped fiber 136 is fused to the first signal light port 112, and the second erbium-doped fiber 138 is fused to the second signal light port 113.

[0045] The first port 151 of the four-port optical ring module of the optical circulator 150 is also connected to the first splitter and photoelectric detection hybrid device 148, which has a splitter and a photodetector. After the signal light is incident on the first splitter and photoelectric detection hybrid device 148, the splitter divides the signal light into two parts. About 5% of the signal light is incident on the photodetector and is used to detect the optical power of the incident signal light. About 95% of the signal light will continue to be transmitted and incident on the first port 151. The signal light passing through the first port 151 can only be emitted from the second port 152 and incident on the first signal light port 112 after passing through the first erbium-doped optical fiber 136.

[0046] See also Figure 2 The four-port optical hybrid device of this embodiment includes a quad-fiber pigtail 120, a collimating lens 125, a filter 130, a polarization rotator 140, and a reflector 145. The quad-fiber pigtail 120 includes a capillary tube, within which are disposed four optical fibers: a pump fiber 121, a pump fiber 122, and a signal fiber 123, and a signal fiber 124. The pump fibers 121 and 122 are connected to the first pump optical port 111 and the second pump optical port 114, respectively. The signal fibers 123 and 124 are connected to the first signal optical port 112 and the second signal optical port 113, respectively.

[0047] The collimating lens 125 is disposed at one end of the quad-fiber pigtail 120. The pump light emitted from the pump fibers 121 and 122 or the signal light emitted from the signal fibers 123 and 124 passes through the collimating lens 125. The collimating lens 125 can be a beam expander lens, a gradient index lens, a spherical lens, or an aspherical lens.

[0048] A filter 130 is provided at one end of the collimating lens 125 away from the quad-fiber pigtail 120. The filter 130 reflects optical signals of a specific wavelength, while optical signals of other wavelengths can pass through the filter 130. In this embodiment, the filter 130 reflects the first pump light and the second pump light, while the optical signals emitted from the signal optical fibers 123 and 124 can pass through the filter 130. The reflected pump light will be incident on the signal optical fiber. For example, the pump light emitted from the pump optical fiber 121 is reflected to the signal optical fiber 124 after passing through the filter 130, and the pump light emitted from the pump optical fiber 122 is reflected to the signal optical fiber 123 after passing through the filter 130. Figure 2 shown.

[0049] The filter 130 can be a flat plate or a thin plate with a wedge angle, preferably a thin plate with a wedge angle. The thin plate with a wedge angle can reflect the pump light to the corresponding signal fiber and avoid interference with the signal light. The signal light can pass through the filter 130 and be incident on the polarization rotator 140.

[0050] In this embodiment, the polarization rotator 140 is positioned at the end of the filter 130 away from the collimating lens 125. It comprises a Faraday rotator with a magnetic ring 141 positioned outside the plate. When the signal light passes through the Faraday rotator, the polarization state of the signal light rotates in a direction that follows the right-hand rule. By controlling the magnetic field strength of the magnetic ring 141, the polarization direction of the signal light can be rotated 45°. The polarization-rotated signal light is then incident on the reflector 145.

[0051] In this embodiment, the reflector 145 is a convex lens having a convex surface 146. Convex surface 146 is located at the end face near the polarization rotator 140. A reflective coating is applied to the flat surface 147 of the reflector 145, which is the end face away from the polarization rotator 140. After passing through the collimating lens 125, the signals emitted from the signal fibers 123 and 124 intersect at the front focal point of the convex lens. After entering the convex surface 146, the light signals are refracted and parallelized. The reflective coating on flat surface 147 reflects the signal light, returning it to its original path. Specifically, the signal light emitted from the signal fiber 123 is reflected back to the signal fiber 123, and the signal light emitted from the signal fiber 124 is reflected back to the signal fiber 124.

[0052] The returning signal light passes through the polarization rotation device 140 again, where its polarization direction is rotated 45° in the same direction. Specifically, when the signal light first passes through the Faraday rotator, its polarization direction is rotated 45° in a direction that follows the right-hand rule. After being reflected, the signal light passes through the Faraday rotator again, and again in a direction that follows the right-hand rule. Therefore, after passing through the Faraday rotator twice, the polarization state of the signal light has rotated 90° compared to when it was not incident on the Faraday rotator. Therefore, the polarization directions of the reflected signal light and the incident signal light are perpendicular to each other. This prevents interference between the incident and reflected signal light due to birefringence, ensuring that the optical signals emitted from signal fibers 123 and 124 are not distorted.

[0053] In this embodiment, the signal light is incident from the second port 152 of the four-port optical ring module of the optical circulator 150 through the first erbium-doped fiber 136 to the first signal light port 112. After being coupled with the first pump light, the first stage of optical power amplification is achieved. The signal light is emitted from the first signal light port 112, passes through the first erbium-doped fiber 136, and returns to the second port 152. The signal light is then emitted from the third port 153 of the four-port optical ring module of the optical circulator 150, passes through the second erbium-doped fiber 138, and is incident on the second signal light port 113 of the optical composite device assembly 110. The signal light after the first stage of amplification is coupled with the second pump light to achieve the second stage of optical power amplification. The amplified signal light passes through the second erbium-doped fiber 138 again and returns to the third port 153. Finally, the signal light is emitted from the fourth port 154 of the four-port optical ring module of the optical circulator 150.

[0054] from Figure 1 It can be seen that the fourth port 154 of the four-port optical ring module of the optical circulator 150 is connected to the second splitting and photoelectric detection hybrid device 149, which has a splitter and a photodetector for detecting the optical power of the optical signal after two-stage optical power amplification.

[0055] Because the signal light undergoes two passes through the erbium-doped fiber at each stage of optical power amplification, the signal light's optical power is boosted during these passes. Compared to conventional fiber optic amplifiers, this embodiment can save half the length of the erbium-doped fiber to achieve the same optical power boost. Furthermore, the signal light can undergo two stages of amplification within the optical composite device assembly 110, effectively boosting the signal light's optical power. These two stages of amplification can share the same filters 130, reflectors 145, and other components, resulting in a more compact fiber optic amplifier.

[0056] In addition, this embodiment can also achieve a first-stage amplification of optical signals. The three-port optical ring module of the optical circulator 150 has three ports: a first port 155, a second port 156, and a third port 157. Optical signals can only be transmitted in one direction within the three-port optical ring module. That is, an optical signal incident from the first port 155 can only be emitted from the second port 156, and an optical signal incident from the second port 156 can only be emitted from the third port 157.

[0057] The second port 156 is connected to a two-port optical hybrid device 160 through an erbium-doped optical fiber 193. The two-port optical hybrid device 160 has two ports, namely a first port 161 and a second port 162. Figure 3 The two-port optical hybrid device 160 includes a pigtail 170, a collimating lens 175, a filter 180, a polarization rotator 181, and a reflector 185, which are arranged in sequence along the optical path. The pigtail 170 includes a capillary tube, within which are disposed two optical fibers: a pump fiber 171 and a signal fiber 172. The pump fiber 171 is connected to the first port 161, and the signal fiber 172 is connected to the second port 162.

[0058] A collimating lens 175 is disposed at one end of the pigtail 170. The pump light emitted from the pump fiber 171 and the signal light emitted from the signal fiber 172 both pass through the collimating lens 175. A filter 180 is disposed at the end of the collimating lens 175 away from the pigtail 170. This filter 180 reflects the pump light emitted from the pump fiber 171, while allowing the optical signal emitted from the signal fiber 172 to pass through the filter 180. Specifically, the pump light emitted from the pump fiber 171 passes through the filter 180 and is reflected to the signal fiber 172.

[0059] After passing through filter 180, the signal light will pass through polarization rotator 181, which includes a Faraday rotator and a magnetic ring 182. The polarization direction of the signal light will be rotated 45° when passing through polarization rotator 181. The signal light passing through polarization rotator 181 will be incident on reflector 185. In this embodiment, reflector 185 is a plane reflector with a reflective film 187 coated on its end face near polarization rotator 181. Reflector 185 is used to reflect the signal light back along its original path, that is, to signal fiber 172, thereby achieving coupling between the signal light and the pump light. Of course, reflector 185 can also be wedge-shaped, roof-shaped, concave, or convex lens-shaped, that is, it can correct the shape of the optical path parallel to the central axis.

[0060] The signal light reflected by the reflector 185 will again pass through the polarization rotation element 181, where its polarization direction will be rotated by 45° in the same direction. This will cause the polarization state of the signal light to be rotated by 90° compared to when it was not incident on the Faraday rotator. This can avoid the problem of signal light interference caused by birefringence between the incident signal light and the reflected signal light.

[0061] When only one level of signal light amplification is required, the signal light undergoes optical power detection through the first optical splitter and photoelectric detection hybrid device 191, then enters the first port 155 of the three-port optical ring module of the optical circulator 150 and exits from the second port 156. After passing through the erbium-doped fiber 193, the signal light enters the second port 162 of the two-port optical hybrid device 160. The signal light is coupled with the pump light entering from the first port 161. After the coupling, the signal light passes through the erbium-doped fiber 193 and enters the second port 156 again, exiting from the third port 157. The third port 157 is connected to the second optical splitter and photoelectric detection hybrid device 192, which is used to detect the optical power of the signal light after optical power amplification.

[0062] In this way, users can flexibly choose to amplify the optical signal in one stage or two stages. The structure of the fiber optic amplifier is very compact, which can meet the requirements of installation and use in limited space.

[0063] Second embodiment:

[0064] See also Figure 4The fiber optical amplifier of this embodiment includes an optical circulator 250, an optical composite device assembly, and a two-port optical hybrid device 260. The optical circulator 250 integrates a four-port optical ring module and a three-port optical ring module. The four-port optical ring module and the three-port optical ring module operate independently and can share some optical components. The four-port optical ring module has a first port 251, a second port 252, a third port 253, and a fourth port 254. The three-port optical ring module has a first port 255, a second port 256, and a third port 257.

[0065] Unlike the first embodiment, in this embodiment, the optical composite device assembly includes a first two-port optical hybrid device 210 and a second two-port optical hybrid device 220. The structure of the first two-port optical hybrid device 210 is the same as that of the two-port optical hybrid device 160 of the first embodiment, and the structure of the second two-port optical hybrid device 220 is also the same as that of the two-port optical hybrid device 160 of the first embodiment. Therefore, the first two-port optical hybrid device 210 is provided with a first filter, a first polarization rotator, and a first reflector, which are sequentially arranged along the optical path. The second two-port optical hybrid device 220 is provided with a second filter, a second polarization rotator, and a second reflector, which are sequentially arranged along the optical path.

[0066] The first two-port optical hybrid device 210 has a first pump light port 211 and a first signal light port 212. The first pump light port 211 receives the first pump light generated by the first pump light source 235 via an optical fiber. The first signal light port 212 is connected to the second port 252 of the four-port optical ring module of the optical circulator 250 via a first erbium-doped fiber 236. The second two-port optical hybrid device 220 has a second pump light port 221 and a second signal light port 222. The second pump light port 221 receives the second pump light generated by the second pump light source 237 via an optical fiber. The second signal light port 222 is connected to the third port 253 of the four-port optical ring module of the optical circulator 250 via a second erbium-doped fiber 238.

[0067] After the initial incident signal light undergoes optical power detection by the first optical splitter and photodetection hybrid device 248, it enters the first port 251. The signal light passing through the first port 251 can only be emitted from the second port 252, and after passing through the first erbium-doped fiber 236, it enters the first signal light port 212. After coupling with the first pump light, the signal light exits the first signal light port 212, enters the second port 252, and then exits from the third port 253. After passing through the second erbium-doped fiber 238, it enters the fourth port 254, and after undergoing optical power detection by the second optical splitter and photodetection hybrid device 249, it is finally emitted. In this way, the incident and outgoing signal light undergoes two stages of amplification, significantly increasing the optical power of the signal light.

[0068] The first port 255 of the three-port optical ring module of the optical circulator 250 is connected to a first light splitting and photodetection hybrid device 291. The second port 256 is connected to a two-port optical hybrid device 260 via an erbium-doped fiber 293. The two-port optical hybrid device 260 has two ports: a first port 261 and a second port 262. The structure of the two-port optical hybrid device 260 is the same as that of the two-port optical hybrid device 160 of the first embodiment and will not be further described. The third port 257 of the three-port optical ring module of the optical circulator 250 is connected to the second light splitting and photodetection hybrid device 292.

[0069] If only one-stage amplification of the signal light is required, the signal light is incident on the first port 255 after passing through the first spectrometer and photoelectric detection hybrid device 291, and passes through the erbium-doped fiber 293 and the two-port optical hybrid device 260, and then passes through the erbium-doped fiber 293 again and is emitted from the third port 257. The optical signal after optical power amplification is detected by the second spectrometer and photoelectric detection hybrid device 292.

[0070] Third embodiment:

[0071] See also Figure 5 This embodiment includes an optical circulator 350 and an optical composite device assembly 310. Unlike the first embodiment, the optical circulator 350 of this embodiment is only equipped with a four-port optical ring module and does not include a three-port optical circulator module. The optical circulator 350 has a first port 351, a second port 352, a third port 353, and a fourth port 354.

[0072] The structure of the optical composite device assembly 310 is the same as that of the optical composite device assembly 110 of the first embodiment, and includes a first pump light port 311, a first signal light port 312, a second signal light port 313, and a second pump light port 314. The first pump light port 311 receives first pump light generated by a first pump light source 335 via an optical fiber. The first signal light port 312 is connected to a second port 352 of an optical circulator 350 via a first erbium-doped fiber 336. The second pump light port 314 receives second pump light generated by a second pump light source 337 via an optical fiber. The second signal light port 314 is connected to a third port 353 of the optical circulator 350 via a second erbium-doped fiber 338.

[0073] After the initial incident signal light undergoes optical power detection by the first optical splitter and photodetection hybrid device 348, it enters the first port 351 of the optical circulator 350. The signal light passing through the first port 351 can only be emitted from the second port 352, and after passing through the first erbium-doped fiber 336, it enters the first signal light port 312. After coupling with the first pump light, the signal light exits the first signal light port 312, enters the second port 352, and then exits from the third port 353. After passing through the second erbium-doped fiber 338, it enters the fourth port 354, and after undergoing optical power detection by the second optical splitter and photodetection hybrid device 349, it is finally emitted. In this way, the incident and outgoing signal light undergoes two stages of amplification, significantly increasing the optical power of the signal light.

[0074] Fourth embodiment:

[0075] See also Figure 6 The fiber optical amplifier of this embodiment includes an optical circulator 450 and an optical composite device assembly, wherein the optical circulator 450 is only provided with a four-port optical ring module, which has a first port 451, a second port 452, a third port 453 and a fourth port 454.

[0076] The optical composite device assembly includes a first two-port optical hybrid device 410 and a second two-port optical hybrid device 420. The structure of the first two-port optical hybrid device 410 is the same as that of the two-port optical hybrid device 160 of the first embodiment, and the structure of the second two-port optical hybrid device 420 is also the same as that of the two-port optical hybrid device 160 of the first embodiment, and thus will not be repeated.

[0077] The first two-port optical hybrid device 410 has a first pump light port 411 and a first signal light port 412. The first pump light port 411 receives the first pump light generated by the first pump light source 435 via an optical fiber. The first signal light port 412 is connected to the second port 452 of the optical circulator 450 via a first erbium-doped fiber 436. The second two-port optical hybrid device 420 has a second pump light port 421 and a second signal light port 422. The second pump light port 421 receives the second pump light generated by the second pump light source 437 via an optical fiber. The second signal light port 422 is connected to the third port 453 of the optical circulator 450 via a second erbium-doped fiber 438.

[0078] The initially incident signal light undergoes optical power detection by the first optical splitter and photodetector hybrid device 448 before entering the first port 451. The signal light passing through the first port 451 can only exit from the second port 452, passing through the first erbium-doped fiber 436 and entering the first signal light port 412. After coupling with the first pump light, the signal light exits from the first signal light port 412 and enters the second port 452. It then exits from the third port 453, passes through the second erbium-doped fiber 438 and enters the fourth port 454. After optical power detection is performed by the second optical splitter and photodetector hybrid device 449, the signal light is finally exited. In this way, the signal light undergoes two stages of amplification, significantly increasing its optical power.

[0079] Fifth embodiment:

[0080] See also Figure 7 This embodiment includes an optical circulator 550 and an optical composite device assembly 510. The optical composite device assembly 510 of this embodiment has the same structure as the optical composite device assembly 110 of the first embodiment, and has a first pump light port 511, a first signal light port 512, a second signal light port 513, and a second pump light port 514. The first pump light port 511 receives first pump light generated by a first pump light source 535 via an optical fiber. The first signal light port 512 is connected to the second port 552 of the optical circulator 350 via a first erbium-doped fiber 536. The second pump light port 514 receives second pump light generated by a second pump light source 537 via an optical fiber. The second signal light port 514 is connected to the third port 553 of the optical circulator 550 via a second erbium-doped fiber 538.

[0081] The optical circulator 550 of this embodiment is a four-port optical ring module having a first port 551, a second port 552, a third port 553, and a fourth port 554. Unlike the third embodiment, the optical circulator 550 of this embodiment further integrates a first and a second optical splitting and photodetection hybrid modules. It can be understood that this embodiment integrates the first and second optical splitting and photodetection hybrid devices 348 and 349 of the third embodiment into the optical circulator 550.

[0082] The first optical splitter and photoelectric detection hybrid device 348 receives the signal light input from the first port 551 and detects the optical power of the signal light. The detected signal light enters the four-port optical ring module and exits from the second port 552 of the optical circulator 550. After passing through the first erbium-doped fiber 536, it is incident on the first signal light port 512. The signal light exiting from the second signal light port 513 passes through the second erbium-doped fiber 538 and enters the third port 553 of the optical circulator 550. The optical power is detected by the second optical splitter and photoelectric detection hybrid module before it is finally emitted from the fourth port 554. It can be seen that in this embodiment, the first port 551 is the signal light input port of the optical circulator, and the fourth port is the signal light output port of the optical circulator.

[0083] In this way, the structure of the fiber optic amplifier is made more compact, which is conducive to miniaturization of the fiber optic amplifier.

[0084] Sixth embodiment:

[0085] See also Figure 8 The fiber optical amplifier of this embodiment includes an optical circulator 650 and an optical composite device assembly, wherein the optical circulator 650 is a four-port optical ring module having a first port 651, a second port 652, a third port 653 and a fourth port 654.

[0086] The optical composite device assembly includes a first two-port optical hybrid device 610 and a second two-port optical hybrid device 620. The structure of the first two-port optical hybrid device 610 is the same as that of the two-port optical hybrid device 160 of the first embodiment, and the structure of the second two-port optical hybrid device 620 is also the same as that of the two-port optical hybrid device 160 of the first embodiment.

[0087] The first two-port optical hybrid device 610 has a first pump light port 611 and a first signal light port 612. The first pump light port 611 receives the first pump light generated by the first pump light source 635 via an optical fiber. The first signal light port 612 is connected to the second port 652 of the optical circulator 650 via a first erbium-doped fiber 636. The second two-port optical hybrid device 620 has a second pump light port 621 and a second signal light port 622. The second pump light port 621 receives the second pump light generated by the second pump light source 637 via an optical fiber. The second signal light port 622 is connected to the third port 653 of the optical circulator 650 via a second erbium-doped fiber 638.

[0088] Unlike the fourth embodiment, the optical circulator 650 of this embodiment further integrates a first light splitting and photodetection hybrid module and a second light splitting and photodetection hybrid module. It can be understood that this embodiment integrates the first light splitting and photodetection hybrid device 448 and the second light splitting and photodetection hybrid device 449 of the fourth embodiment into the optical circulator 650. This makes the structure of the fiber optical amplifier more compact, facilitating miniaturization of the fiber optical amplifier.

[0089] Seventh embodiment:

[0090] See also Figure 9 The fiber optical amplifier of this embodiment includes an optical circulator 750 and an optical composite device assembly. The optical circulator is a three-port optical ring module having a first port 751, a second port 752, and a third port 753. Furthermore, a first optical splitting and photoelectric detection hybrid module and a second optical splitting and photoelectric detection hybrid module are integrated within the optical circulator 750.

[0091] The optical composite device assembly of this embodiment is a two-port optical hybrid device 710. The structure of optical hybrid device 710 is identical to that of the two-port optical hybrid device 160 of the first embodiment and is not further described. Optical hybrid device 710 has a pump light port 711 and a signal light port 712. Pump light port 711 is connected to a pump light source 737 via an optical fiber, while signal light port 712 is connected to a second port 752 of an optical circulator 750 via an erbium-doped optical fiber 738.

[0092] The optical circulator 750 of this embodiment also integrates a first spectrometer and photoelectric detection hybrid module and a second spectrometer and photoelectric detection hybrid module. The first spectrometer and photoelectric detection hybrid module is connected to the first port 751 as the signal light incident port, and the second spectrometer and photoelectric detection hybrid module is connected to the third port 75 as the signal light output port.

[0093] Of course, the above scheme is only a preferred embodiment of the present invention. There are more changes in actual application, such as changes in the internal structure of the optical composite device component, or changes in the internal structure of the optical circulator, etc. These changes should also be included in the scope of protection of the claims of the present invention.

Claims

1. A fiber optical amplifier, comprising: An optical circulator, wherein the optical circulator has at least four ports, and a first port of the optical circulator receives signal light; Characterized in that the fiber optical amplifier further comprises: An optical composite device assembly having a first pump light port, a second pump light port, a first signal light port, and a second signal light port, wherein the first pump light port receives a first pump light, a first erbium-doped optical fiber is connected between the first signal light port and the second port of the optical circulator, a second erbium-doped optical fiber is connected between the second signal light port and the third port of the optical circulator, and the second pump light port receives a second pump light; The optical composite device assembly includes a filter, a polarization state rotator, and a reflector. The filter reflects the first pump light to the first signal light port, and the filter also reflects the second pump light to the second signal light port. The reflector reflects the incident signal light along the original path. After the signal light passes through the polarization state rotator twice, the polarization direction is rotated by 90°.

2. The fiber optical amplifier according to claim 1, wherein: The optical composite device assembly is a four-port optical hybrid device, in which a filter and a reflector are provided. The first pump light and the second pump light are both reflected by the filter, and the signal light incident from the first signal light port and the second signal light port are both reflected by the reflector.

3. The fiber optical amplifier according to claim 2, wherein: The four-port optical hybrid device further comprises a four-wire pigtail, wherein the four-wire pigtail is provided with two pump optical fibers and two signal optical fibers; A collimating lens is provided at one end of the four-wire pigtail, the filter is provided at one end of the collimating lens away from the four-wire pigtail, and the reflector is provided at one end of the filter away from the collimating lens.

4. The fiber optical amplifier according to claim 3, wherein: A polarization state rotation device is further provided between the filter and the reflector. Each time the signal light passes through the polarization state rotation device, the polarization direction is rotated by 45° along the same rotation direction.

5. The fiber optical amplifier according to claim 1, wherein: The optical composite device assembly includes a first two-port optical hybrid device and a second two-port optical hybrid device, the first pump light port and the first signal light port are arranged in the first two-port optical hybrid device, and the second pump light port and the second signal light port are arranged in the second two-port optical hybrid device.

6. The fiber optical amplifier according to claim 5, wherein: The first two-port optical hybrid device further includes a first filter, a first polarization state rotation device and a first reflector which are sequentially arranged along the optical path; The second two-port optical hybrid device further includes a second filter, a second polarization state rotation device and a second reflector which are sequentially arranged along the optical path.

7. The fiber optical amplifier according to any one of claims 1 to 6, wherein: The first port of the optical circulator is connected to a first light splitting and photoelectric detection hybrid device; and / or The fourth port of the optical circulator is connected to a second light splitting and photoelectric detection hybrid device.

8. The fiber optical amplifier according to any one of claims 1 to 6, wherein: The optical circulator is provided with a first spectrometer and photoelectric detection hybrid module and a second spectrometer and photoelectric detection hybrid module. The first spectrometer and photoelectric detection hybrid module is connected to the signal light incident port of the optical circulator, and the second spectrometer and photoelectric detection hybrid module is connected to the signal light output port of the optical circulator.

9. The fiber optical amplifier according to any one of claims 1 to 6, wherein: The optical circulator includes a four-port optical ring module and a three-port optical ring module, and the optical composite device assembly is connected to the second port and the third port of the four-port optical ring module.

10. The fiber optical amplifier according to claim 9, wherein: The first port of the three-port optical ring module receives signal light, and the second port of the three-port optical ring module is connected to a third two-port optical hybrid device through a third section of erbium-doped optical fiber. The third two-port optical hybrid device includes a third filter, a third polarization state rotation device, and a third reflector arranged in sequence along the optical path. The third filter reflects the pump light incident from one port of the third two-port optical hybrid device to the signal light port, and the reflector reflects the incident signal light along the original path.

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