Single-fiber reflective polarization-maintaining fiber amplifier

Abstract

The application relates to a polarization maintaining fiber amplifier, in particular to a single-fiber reflection type polarization maintaining fiber amplifier, which comprises a polarization beam splitter PBS, a first Faraday optical rotator, a second Faraday optical rotator, an input polarization maintaining fiber collimator, a first polarization maintaining fiber collimator, a second polarization maintaining fiber collimator and a gain amplification unit, the input polarization maintaining fiber collimator is connected with an input polarization maintaining fiber, the input polarization maintaining fiber collimator is aligned with port 3 of the polarization beam splitter PBS, and a first Faraday optical rotator is arranged between the input polarization maintaining fiber collimator and the port 3 of the polarization beam splitter PBS; port 1 of the polarization beam splitter PBS is aligned with the first polarization maintaining fiber collimator, the first polarization maintaining fiber collimator is connected with an input end of the gain amplification unit, and an output end of the gain amplification unit is connected with the second polarization maintaining fiber collimator; the technical scheme can effectively overcome the defect that the optical signal cannot be amplified and returned along the same optical fiber in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to polarization maintaining fiber amplifier, in particular to single fiber reflection type polarization maintaining fiber amplifier. BACKGROUND

[0002] In polarization maintaining fiber system, the promotion of laser power usually depends on polarization maintaining fiber amplifier. The conventional polarization maintaining fiber amplifier has two fiber ports of input end and output end, that is, the optical signal can only transmit from the input end to the output end. However, in some specific application occasions, the optical signal needs to be amplified and returned along the same fiber, and the existing polarization maintaining fiber amplifier basically does not have this function. SUMMARY

[0003] (I) Technical problems to be solved

[0004] In view of the above defects existing in the prior art, the single fiber reflection type polarization maintaining fiber amplifier is provided, which can effectively overcome the defect that the optical signal cannot be amplified and returned along the same fiber after amplification.

[0005] (II) Technical scheme

[0006] In order to achieve the above purpose, the technical scheme is as follows:

[0007] The single fiber reflection type polarization maintaining fiber amplifier comprises a polarization beam splitter PBS, a first Faraday optical rotator, a second Faraday optical rotator, an input polarization maintaining fiber collimator, a first polarization maintaining fiber collimator, a second polarization maintaining fiber collimator and a gain amplification unit. The input polarization maintaining fiber collimator is connected with an input polarization maintaining fiber. The input polarization maintaining fiber collimator is aligned with port 3 of the polarization beam splitter PBS, and a first Faraday optical rotator is arranged between the input polarization maintaining fiber collimator and port 3 of the polarization beam splitter PBS.

[0008] Port 1 of the polarization beam splitter PBS is aligned with the first polarization maintaining fiber collimator. The first polarization maintaining fiber collimator is connected with the input end of the gain amplification unit. The output end of the gain amplification unit is connected with the second polarization maintaining fiber collimator. The second polarization maintaining fiber collimator is aligned with port 2 of the polarization beam splitter PBS, and a second Faraday optical rotator is arranged between the second polarization maintaining fiber collimator and port 2 of the polarization beam splitter PBS.

[0009] Preferably, the included angle between the slow axis of the input polarization maintaining fiber and the optical axis of the polarization beam splitter PBS is 45°. The first Faraday optical rotator is a 45° Faraday optical rotator. The second Faraday optical rotator is a 90° Faraday optical rotator.

[0010] Preferably, the gain amplification unit includes a pump laser, a wavelength division multiplexer WDM and a gain fiber, the input end of the wavelength division multiplexer WDM is connected to the pump laser and the first polarization-maintaining fiber collimator, and the output end of the wavelength division multiplexer WDM is connected to the second polarization-maintaining fiber collimator through the gain fiber.

[0011] Preferably, a beam splitter TAP is provided between the gain fiber and the second polarization-maintaining fiber collimator, the input end of the beam splitter TAP is connected to the gain fiber, one output end of the beam splitter TAP is connected to a photodetector, and the other output end of the beam splitter TAP is connected to the second polarization-maintaining fiber collimator.

[0012] Preferably, all connecting optical fibers in a single-fiber reflective polarization-maintaining fiber amplifier are single-mode polarization-maintaining fibers, and the single-mode polarization-maintaining fiber adopts a panda-type polarization-maintaining fiber, the panda eye connection direction of the panda-type polarization-maintaining fiber is the slow axis of the polarization-maintaining fiber, and the panda eye connection direction perpendicular to the panda eye of the panda-type polarization-maintaining fiber is the fast axis of the polarization-maintaining fiber.

[0013] (3) Beneficial effects

[0014] Compared with the existing technology, the single-fiber reflective polarization-maintaining fiber amplifier provided by the present invention can effectively amplify the optical signal in the single-fiber state, and can guide the amplified optical signal back along the original path from the input polarization-maintaining fiber, which is convenient for use in specific application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0016] Figure 1 It is a schematic diagram of the structure and working principle of the present invention;

[0017] Figure 2 This is a physical picture of the polarization beam splitter PBS in the present invention. DETAILED DESCRIPTION

[0018] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] Single-fiber reflective polarization-maintaining fiber amplifier, such as Figure 1 As shown, it includes a polarization beam splitter PBS, a first Faraday rotator, a second Faraday rotator, an input polarization-maintaining fiber collimator, a first polarization-maintaining fiber collimator, a second polarization-maintaining fiber collimator and a gain amplifier unit. The input polarization-maintaining fiber collimator is connected to the input polarization-maintaining fiber. The input polarization-maintaining fiber collimator is aligned with port 3 of the polarization beam splitter PBS, and a first Faraday rotator is provided between the input polarization-maintaining fiber collimator and port 3 of the polarization beam splitter PBS.

[0020] Port 1 of the polarization beam splitter PBS is aligned with the first polarization-maintaining fiber collimator, the first polarization-maintaining fiber collimator is connected to the input end of the gain amplifier unit, the output end of the gain amplifier unit is connected to the second polarization-maintaining fiber collimator, the second polarization-maintaining fiber collimator is aligned with port 2 of the polarization beam splitter PBS, and a second Faraday rotator is provided between the second polarization-maintaining fiber collimator and port 2 of the polarization beam splitter PBS.

[0021] In the technical solution of the present application, the angle between the slow axis of the input polarization-maintaining optical fiber and the optical axis of the polarization splitting crystal inside the polarization beam splitter PBS is 45°, the first Faraday rotator is a Faraday rotator with 45° optical rotation, and the second Faraday rotator is a Faraday rotator with 90° optical rotation.

[0022] like Figure 1 As shown, the gain amplification unit includes a pump laser, a wavelength division multiplexer (WDM), and a gain fiber. The pump laser provides excitation energy to the gain fiber through the wavelength division multiplexer (WDM). The input end of the wavelength division multiplexer (WDM) is connected to the pump laser and the first polarization-maintaining fiber collimator. The output end of the wavelength division multiplexer (WDM) is connected to the second polarization-maintaining fiber collimator through the gain fiber.

[0023] like Figure 1 As shown, a beam splitter TAP is provided between the gain fiber and the second polarization-maintaining fiber collimator. The input end of the beam splitter TAP is connected to the gain fiber, one output end of the beam splitter TAP is connected to a photodetector, and the other output end of the beam splitter TAP is connected to the second polarization-maintaining fiber collimator.

[0024] In the technical solution of the present application, all connecting optical fibers in the single-fiber reflective polarization-maintaining fiber amplifier are single-mode polarization-maintaining fibers. The single-mode polarization-maintaining fiber adopts a panda-type polarization-maintaining fiber. The panda eye connection direction of the panda-type polarization-maintaining fiber is the slow axis of the polarization-maintaining fiber, and the panda eye connection direction perpendicular to the panda-type polarization-maintaining fiber is the fast axis of the polarization-maintaining fiber.

[0025] The pump laser provides excitation energy to the gain fiber through a wavelength division multiplexer (WDM), one input end of the wavelength division multiplexer (WDM) is connected to a first polarization maintaining fiber collimator of port 1 of a polarization beam splitter (PBS), the gain fiber is connected to a beam splitter (TAP), a small part of the amplified optical signal enters a photoelectric detector for power monitoring after being split, and another part of the amplified optical signal passes through a second polarization maintaining fiber collimator and is connected to port 2 of the polarization beam splitter (PBS). Figure 1 The dashed line in the figure represents the optical signal transmission trajectory, Figure 1 The bold short line in the figure represents the polarization direction of the optical signal at each position.

[0026] The working principle of the technical scheme of the present application is briefly described below taking the input optical signal as a slow axis light as an example:

[0027] Since the angle between the slow axis of the input polarization maintaining fiber and the optical axis of the polarization beam splitter (PBS) internal polarization splitting crystal is 45°, the polarization direction of the input optical signal is parallel to the optical axis of the polarization beam splitter (PBS) internal polarization splitting crystal after passing through the first Faraday rotator with 45° optical rotation;

[0028] After being split by the polarization beam splitter (PBS), the optical signal is reflected to port 1, enters the gain amplification unit through the first polarization maintaining fiber collimator, the optical signal power is amplified and polarization maintaining transmission, and the polarization direction always remains horizontal;

[0029] After passing through the second Faraday rotator with 90° optical rotation after the second polarization maintaining fiber collimator, the polarization direction becomes vertical, so that the optical signal is transmitted through the polarization beam splitter (PBS) internal polarization splitting crystal and is shot to port 3;

[0030] After encountering the first Faraday rotator with 45° optical rotation, the polarization direction is changed to 45° due to the counterclockwise rotation of 45°, which is parallel to the slow axis of the input polarization maintaining fiber, so that the optical signal can return from the input polarization maintaining fiber, and the entire amplification process is completed.

[0031] The above embodiments are only used to illustrate the technical scheme of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical scheme recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements will not make the essence of the corresponding technical scheme deviate from the spirit and scope of the technical scheme of the embodiments of the present application.

Claims

1. Single-fiber reflective polarization-maintaining fiber amplifier, characterized by: The optical fiber collimator comprises a polarization beam splitter (PBS), a first Faraday rotator, a second Faraday rotator, an input polarization-maintaining fiber collimator, a first polarization-maintaining fiber collimator, a second polarization-maintaining fiber collimator, and a gain amplifier unit. The input polarization-maintaining fiber collimator is connected to the input polarization-maintaining fiber. The input polarization-maintaining fiber collimator is aligned with port 3 of the polarization beam splitter (PBS), and a first Faraday rotator is provided between the input polarization-maintaining fiber collimator and port 3 of the polarization beam splitter (PBS). Port 1 of the polarization beam splitter PBS is aligned with a first polarization-maintaining fiber collimator, the first polarization-maintaining fiber collimator is connected to the input end of a gain amplifier unit, the output end of the gain amplifier unit is connected to a second polarization-maintaining fiber collimator, the second polarization-maintaining fiber collimator is aligned with port 2 of the polarization beam splitter PBS, and a second Faraday rotator is provided between the second polarization-maintaining fiber collimator and port 2 of the polarization beam splitter PBS; The gain amplification unit includes a pump laser, a wavelength division multiplexer (WDM) and a gain fiber. The input end of the wavelength division multiplexer (WDM) is connected to the pump laser and the first polarization-maintaining fiber collimator. The output end of the wavelength division multiplexer (WDM) is connected to the second polarization-maintaining fiber collimator through the gain fiber. A beam splitter TAP is provided between the gain fiber and the second polarization-maintaining fiber collimator, the input end of the beam splitter TAP is connected to the gain fiber, one output end of the beam splitter TAP is connected to a photodetector, and the other output end of the beam splitter TAP is connected to the second polarization-maintaining fiber collimator; The angle between the slow axis of the input polarization-maintaining optical fiber and the optical axis of the polarization splitting crystal inside the polarization beam splitter PBS is 45°, the first Faraday rotator is a Faraday rotator with 45° optical rotation, and the second Faraday rotator is a Faraday rotator with 90° optical rotation; All connecting optical fibers in a single-fiber reflective polarization-maintaining fiber amplifier are single-mode polarization-maintaining fibers. The single-mode polarization-maintaining fibers adopt panda-type polarization-maintaining fibers. The panda eye connection direction of the panda-type polarization-maintaining fibers is the slow axis of the polarization-maintaining fibers, and the panda eye connection direction perpendicular to the panda eye connection direction of the panda-type polarization-maintaining fibers is the fast axis of the polarization-maintaining fibers.

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