Optical amplifier and optical amplification method

Abstract

The invention relates to the technical field of optical communication, and particularly provides an optical amplifier and an optical amplification method.The optical amplifier comprises a polarization beam splitting assembly and a bidirectional optical amplification chip, and a first transmission optical path and a second transmission optical path exist between the polarization beam splitting assembly and the optical amplification chip; a first polarization control structure is arranged on the first transmission light path, and a second polarization control structure is arranged on the second transmission light path; according to the light amplification method, a first polarization control structure and a second polarization control structure are used for controlling polarization states of input light and output light in a cooperative manner; any polarized light can be amplified, the low noise and any polarization gain effect of the semiconductor optical amplifier are achieved, the amplified light is adjusted into one beam of output light through the polarization control structure and the polarization beam splitting assembly again, and the light amplification effect is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical communications, and in particular to an optical amplifier and an optical amplification method. Background Art

[0002] Semiconductor optical amplifiers (SOAs) are often used in optical fiber communication systems to enhance the intensity of light. Light will be lost when it is transmitted in an optical fiber, and the magnitude of the loss is proportional to the transmission distance. The main function of SOAs is to amplify weak light to compensate for the loss in optical fiber transmission and extend the optical transmission distance.

[0003] At present, semiconductor optical amplifier (SOA) chips still have problems such as polarization sensitivity and saturation gain limit. Although there are ways to optimize chips on the market to solve the SOA polarization sensitivity problem, the chip R&D technology is difficult, the process cycle is long, and the R&D cost is high, so this method is not ideal.

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an optical amplifier and an optical amplification method for solving the problems that need to be solved urgently in the technical field. Summary of the invention

[0005] The reason why semiconductor optical amplifier chips are polarization sensitive at present is that the chip has different amplification effects on different polarized light, which makes certain polarization directions more susceptible to amplifier noise, thereby increasing the overall noise factor. In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an optical amplifier and an optical amplification method, which are used to solve the application problems of single polarization gain chips in the prior art and polarization gain adjustment of polarization gain sensitive chips, and to optimize the chip to solve the problems of high technical difficulty, long process cycle and high R&D cost of SOA polarization sensitivity.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides an optical amplifier, including a polarization beam splitting component and a bidirectional optical amplifier chip, wherein a first transmission optical path and a second transmission optical path are provided between the polarization beam splitting component and the bidirectional optical amplifier chip; a first polarization control structure is provided on the first transmission optical path, and a second polarization control structure is provided on the second transmission optical path; the first polarization control structure includes a first Faraday rotator and a first wave plate; the second polarization control structure includes a second Faraday rotator and a second wave plate;

[0007] The polarization beam splitter assembly is provided with a first port, a second port, a third port, and a fourth port, wherein the first port is used to receive incident light, the second port is used to output one of the two input lights with orthogonal polarization directions and transmit the light to the first polarization control structure; the third port is used to output the other of the two input lights with orthogonal polarization directions and transmit the light to the second polarization control structure, and the fourth port is used to output the amplified light;

[0008] The second port of the polarization beam splitting component, the first polarization control structure, the bidirectional optical amplifier chip, the polarization control structure, and the third port of the polarization beam splitting component are combined to form a series optical path.

[0009] In one embodiment of the present invention, the two beams of polarized light output by the polarization beam splitter component have orthogonal polarization states, one of which will enter the series optical path in the forward direction from the second port, and enter the polarization beam splitter component from the third port after being amplified and polarization adjusted; the other beam of polarized light will enter the series optical path in the reverse direction from the third port, and enter the polarization beam splitter component from the second port after being amplified and polarization adjusted.

[0010] In one embodiment of the present invention, a second reflector is arranged between the second polarization control structure and the bidirectional optical amplifier chip; the second reflector is composed of two triangular mirrors with 90° reflection surfaces, and the two triangular mirror reflection surfaces are arranged opposite to each other, so that the second reflector has a 180° reflection surface, thereby realizing light transmission between the second polarization control structure and the bidirectional optical amplifier chip; a first reflector is arranged between the polarization beam splitting component and the second polarization control structure, and the first reflector has a 90° reflection surface, which is used to realize light transmission between the polarization beam splitting component and the second polarization control structure.

[0011] In one embodiment of the present invention, lenses are provided on both the first transmission optical path and the second transmission optical path, and the lenses are distributed at the bidirectional optical transmission end of the bidirectional optical amplifier chip.

[0012] In one embodiment of the present invention, the first polarization control structure is used to control the polarization state of the light on the first transmission optical path, so as to output forward polarized light from the second port and output reverse polarized light from the third port; the forward polarized light passes through the first polarization control structure without changing its polarization, and the reverse polarized light passes through the structure with its polarization angle reduced by 1 / 2π+gπ(g∈N 0 );

[0013] The first polarization control structure is used to control the polarization state of the light on the first transmission optical path. After the forward polarized light output from the second port passes through the first polarization control structure, the polarization remains unchanged, and the main value angle of the polarization angle of the amplified reverse polarized light entering the second port is controlled to be the same as the main value angle of the polarization angle when it is output from the third port; the second polarization control structure is used to control the polarization state of the light on the second transmission optical path, and the polarization angle increases by π+kπ(k∈N 0 ), the reverse polarization angle increases by 1 / 2π+gπ(g∈N 0 );

[0014] The second polarization control structure is used to control the reverse polarized light output from the third port to have the same polarization angle as the forward polarized light when entering the bidirectional optical amplifier chip, and to control the principal value angle of the polarization angle of the amplified forward polarized light to be the same as that before amplification when entering the polarization beam splitting component;

[0015] The first polarization control structure and the second polarization control structure respectively control the bidirectional optical amplifier chip to perform low-noise amplification on any polarized light of the input optical amplifier by setting the first Faraday rotator and the first wave plate, the second Faraday rotator and the second wave plate to rotate the polarization angle of the transmitted light.

[0016] In one embodiment of the present invention, the first wave plate and the second wave plate are set to rotate the polarization of the transmitted light at angles γ and φ respectively, and the first Faraday rotator is set to rotate the polarization of the transmitted light at angle δ 1 The second Faraday rotator rotates the polarization of the transmitted light by an angle of δ 2 ;

[0017] The first polarization control structure and the second polarization control structure are respectively provided with a first Faraday rotator and a first wave plate, a second Faraday rotator and a second wave plate to rotate the polarization angle of the transmitted light so that the following equations are all established:

[0018] δ 1 =δ 2 =1 / 4π+(nm)·π, n∈N 0 ;

[0019] γ=1 / 4π+(n+m)·π,n∈N 0 ,m∈N 0 ;

[0020] φ=3 / 4π+(r+n)·π,r∈N 0 , n∈N 0 .

[0021] In one embodiment of the present invention, the light transmission efficiency of the polarization beam splitter is set to t 0 , the light transmission efficiency of the first polarization control structure is t 1 , the light transmission efficiency of the second polarization control structure is t 2 ; Set the gain of the bidirectional optical amplifier chip to g 0 ; Set the power of the input light to P In ; Set the input light to be divided into two orthogonal polarized lights with energies aP x ,bP y ; Set the power of the output light after the input light gain to P out ; Set the gain of the bidirectional optical amplifier chip for the forward input light and the reverse input light in the same polarization state to g respectivelyx , g y ; Set the gain of the optical amplifier for forward polarized light to be G x , G y ; Set the optical amplifier gain to G t ; The PDG is the polarization-dependent gain of the optical amplifier; the difference between the polarization rotation angle of the transmitted light and the polarization rotation angle in the ideal state is set to β 1 ;

[0022] The optical amplifier controls the polarization angle of the input light by setting a polarization control structure to achieve low PDG amplification of any polarized light by the optical amplifier, and the following equations are all established: In =a·P x +b·P y ;

[0023] P out =|cosβ 1 ∣·g x ·t 0 ·t 1 ·t 2 ·a·P x +|sin(1 / 2π-β 1 )∣·t 0 ·t 1 ·t 2 ·g y ·b·P y ;

[0024]

[0025] PDG=G y -G x =g y -g x ;

[0026] G t =G x =G y =|cosβ 1 ∣·g x ·t 0 ·t 1 ·t 2 , ifg y =g x ;

[0027] A light amplification method, comprising the above-mentioned light amplifier, comprises the following steps:

[0028] S1. Use a polarization beam splitting component to split light with any polarization into two polarized lights with orthogonal polarizations. One of the lights is transmitted through the first transmission optical path and passes through the first polarization control structure in the forward direction, and the polarization angle increases by β 1 , β 1 ∈[0, 1 / 2π]; the other light is transmitted through the second transmission optical path and passes through the second polarization control structure in the reverse direction, and the polarization angle decreases by 1 / 2π - β 1 , β 1 ∈[0, 2π]; at this time, the polarization states of the two polarized lights are the same;

[0029] S2. The light transmitted through the first transmission optical path adjusts its polarization through the first polarization control structure, thereby controlling the polarization state of one of the polarized lights entering the bidirectional optical amplification chip; the light transmitted through the second transmission optical path adjusts its polarization through the second polarization control structure, thereby controlling the polarization state of the other polarized light entering the bidirectional optical amplification chip;

[0030] S3. After the two lights are uniformly gain-amplified by the bidirectional optical amplification chip, they are transmitted through each other's transmission optical paths, that is, the light transmitted through the first transmission optical path and entering the bidirectional optical amplification chip enters the second transmission optical path, and after the polarization state is adjusted again by the second control structure, it enters the polarization beam splitting component (1); the light transmitted through the second transmission optical path and entering the bidirectional optical amplification chip enters the first transmission optical path, and after the polarization state is adjusted again by the first control structure, it reaches the polarization beam splitting component; the two polarized lights are adjusted to two orthogonal polarized lights perpendicular to the original polarization state;

[0031] S4. The polarization beam splitting component combines the two amplified polarized lights into one light and outputs it from other ports.

[0032] As described above, the optical amplifier and the optical amplification method of the present invention have the following beneficial effects:

[0033] The present invention uses a polarization beam splitting component, an optical amplification chip, a Faraday rotator, a wave plate, a mirror, and a lens as basic components, and combines and designs the above basic components to form an optical amplifier, so that the SOA can achieve low-noise and uniform gain for light with any polarization under relatively simple structural and technological conditions, effectively reducing the technical difficulty and R & D cost, shortening the process cycle, and having good market application prospects; the present invention adjusts the polarization direction of light through the cooperation of the polarization beam splitting component with the first polarization control structure and the second polarization control structure, separates the input light into two lights with different polarization directions, amplifies them respectively and then combines them into one light for output, enabling the semiconductor optical amplifier to amplify light with any polarization, achieving the low-noise and arbitrary polarization gain effects of the semiconductor optical amplifier, and the amplified light will be adjusted into one output light by the polarization control structure and the polarization beam splitting component again, effectively improving the amplification effect of light. Description of the Drawings

[0034] Figure 1 Shown is a schematic diagram of the structure of the optical amplifier disclosed in the present invention.

[0035] Figure 2 Shown is a schematic diagram of the structure of the optical amplifier disclosed in Example 2.

[0036] Figure 3 Shown is a schematic diagram of the structure of the optical amplifier disclosed in Example 3.

[0037] Figure 4 Shown is a schematic diagram of the structure of the optical amplifier disclosed in Example 4.

[0038] Figure 5 Shown is a schematic diagram of the structure of the optical amplifier disclosed in Example 5.

[0039] Component number description

[0040] Polarization beam splitting component 1; optical amplifier chip 2; first Faraday rotator 3; first wave plate 4; second Faraday rotator 5; second wave plate 6; second reflector 7; lens 8; third wave plate 9; lens 8; first polarization control structure 11; second polarization control structure 12; first port 13; second port 14; third port 15; fourth port 16; first reflector 10. DETAILED DESCRIPTION

[0041] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0042] See also Figures 1 to 5 It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0043] Embodiment 1. This embodiment provides an optical amplifier, including a polarization beam splitting component 1 and a bidirectional optical amplification chip 2. The polarization beam splitting component 1 includes a multilayer dielectric film stack or a birefringent crystal, wherein the multilayer dielectric film stack is a multilayer metal oxide film system, which refers to a multilayer structure formed by alternating deposition of two or more metal oxides, and can be prepared by physical vapor deposition PVD or chemical vapor deposition CVD and other methods; the polarization beam splitting component 1 is equipped with a first reflector 10 for reflecting the separated light beam.

[0044] There are a first transmission optical path and a second transmission optical path between the polarization beam splitting component 1 and the bidirectional optical amplifier chip 2, and lenses 8 are provided on the first transmission optical path and the second transmission optical path, and the lenses 8 are distributed at the bidirectional optical transmission end of the bidirectional optical amplifier chip 2. A first polarization control structure 11 is provided on the first transmission optical path, and a second polarization control structure 12 is provided on the second transmission optical path; the first polarization control structure 11 includes a first Faraday rotator 3 and a first wave plate 4, and the first wave plate 4 is set as a 1 / 8 wave plate, that is, the first wave plate 4 has a deflection angle of 360°*1 / 8, that is, a deflection angle of 45°; the second polarization control structure 12 includes a second Faraday rotator 5 and a second wave plate 6; the second wave plate 6 is set as a 3 / 8 wave plate, that is, the second wave plate 6 has a deflection angle of 360°*3 / 8, that is, a deflection angle of 135°; the polarization beam splitting component 1 is provided with a first port 1 3. The second port 14, the third port 15, and the fourth port 16. The first port 13 is used to receive incident light, the second port 14 is used to output one of the two input lights with orthogonal polarization directions, and transmit the light to the first polarization control structure 11; the third port 15 is used to output the other of the two input lights with orthogonal polarization directions, and transmit the light to the second polarization control structure 12, and the fourth port 16 is used to output the amplified light; the second port 14 of the polarization beam splitting assembly, the first polarization control structure 11, the bidirectional optical amplifier chip 2, the polarization control structure 12, and the third port 15 of the polarization beam splitting assembly 1 are combined to form a series optical path.

[0045] The amplification of polarized light by the semiconductor optical amplifier is calculated using the following formula:

[0046] P in =a·P x +b·P y ;

[0047] P out =a·t 0 ·t 1 ·t 2 ·g 0 ·P x +b·t 0 ·t 1 ·t 2 ·g 0 ··P y ;

[0048] t 0 is the light transmission efficiency of polarization beam splitter 1, t 1 is the light transmission efficiency of the first polarization control structure 11, t 2 is the light transmission efficiency of the second polarization control structure 12, g 0 is the optical gain of bidirectional optical amplifier chip 2, and the input optical power is P in, the output optical power is P out ;aP x ,bP y are the energies of the input light divided into two orthogonal polarized lights; the output light power P out =t 0 ·t 1 ·t 2 ·g 0 ·P in , the light input into the optical amplifier can be amplified with arbitrary polarization.

[0049] When the polarization rotation angle of the light by the polarization control structure is in a non-ideal state; when the light passes through the first polarization control structure 11 in the forward direction, the polarization angle increases by β 1 +gπg∈N 0 , β 1 ∈[0,1 / 2π], the polarization angle decreases by 1 / 2π-β after reverse transmission 1 +dπd∈N 0 , β 1 ∈[0,1 / 2π], when the light passes through the second polarization control structure 12 in the reverse direction, the polarization angle decreases by 1 / 2π-β 1 +eπe∈N 0 , β 1 ∈[0,1 / 2π], the polarization angle increases by π-β after passing through in the forward direction 1 +fπf∈N 0 , β 1 ∈[0,1 / 2π]; at this time, the gain effect of the optical amplifier chip on light is:

[0050] P In =a·P x +b·P y ;

[0051] P out =cosβ 1 ·g x ·t 0 ·t 1 ·t 2 ·a·P x +cosβ 1 ·t 0 ·t 1 ·t 2 ·g y ·b·P y ,θ∈[0,2π];

[0052]

[0053] where t 0 is the light transmission efficiency of polarization beam splitter 1, t 1is the light transmission efficiency of the first polarization control structure 11, t 2 is the light transmission efficiency of the second polarization control structure 12, g 0 is the gain of the bidirectional optical amplifier chip 2, P In is the power of the input light, aP x ,bP y are the energy of the input light split into two orthogonal polarized lights, P out is the power of the output light after the input light is gained, β 1 g is the angle of polarization rotation after the light passes through the first polarization control structure 11 in the forward direction and the angle of polarization rotation after the light passes through the second polarization control structure 12 in the reverse direction; x , g y are the gains of the forward input light and the reverse input light of the bidirectional optical amplifier chip 2 under the same polarization state; G x , G y are the gains of the optical amplifier for two beams of orthogonal polarization light;

[0054] At this time, the PGR of the optical amplifier to the input light is:

[0055] PGR=G y -G x =g y -g x ;

[0056] When the chip has equal gains for forward input light and reverse input light in the same polarization state, that is, g x =g y When , the effect of the polarization control structure on the optical amplifier is:

[0057] PDR = 0;

[0058] G t =G x =G y = cosβ 1 ·g x ·t 0 ·t 1 ·t 2 ;

[0059] The G t is the gain of the optical amplifier to light.

[0060] The polarization beam splitter component 1 outputs two beams of polarized light with orthogonal polarization states, one of which will enter the series optical path in the forward direction from the second port 14, and enter the polarization beam splitter component 1 from the third port 15 after being amplified and polarization adjusted; the other polarized light will enter the series optical path in the reverse direction from the third port 15, and enter the polarization beam splitter component 1 from the second port 14 after being amplified and polarization adjusted.

[0061] A second reflector 7 is arranged between the second polarization control structure 12 and the bidirectional optical amplifier chip 2. The second reflector 7 is composed of a reflector with a 180° reflective surface, or the second reflector 7 is composed of two triangular mirrors with 90° reflective surfaces. The two triangular mirror reflective surfaces are arranged opposite to each other, so that the second reflector 7 has a 180° reflective surface, thereby realizing light transmission between the second polarization control structure 12 and the bidirectional optical amplifier chip; a first reflector 10 is arranged between the polarization beam splitting component 1 and the second polarization control structure 12. The first reflector 10 has a 90° reflective surface, which is used to realize light transmission between the polarization beam splitting component 1 and the second polarization control structure 12.

[0062] The first polarization control structure 11 is used to control the polarization state of the light on the first transmission optical path, so as to output forward polarized light from the second port 14 and output reverse polarized light from the third port 15; the forward polarized light passes through the first polarization control structure 11 without polarization change, and the reverse polarized light passes through the first polarization control structure 11 with a polarization angle reduced by 1 / 2π+gπg∈N 0 The first polarization control structure 11 is used to control the forward polarized light output from the second port 14 to remain polarized after passing through the first polarization control structure 11, and to control the principal value angle of the polarization angle of the amplified reverse polarized light when entering the second port 14 to be the same as the principal value angle of the polarization angle when output from the third port 15; the second polarization control structure 12 is used to control the polarization state of the light on the second transmission optical path, and the polarization angle of the light passing through the second polarization control structure 12 in the forward direction increases by π+kπk∈N 0 , the reverse polarization angle increases by 1 / 2π+gπg∈N 0 The second polarization control structure is used to control the reverse polarized light output from the third port 15 to have the same polarization angle as the forward polarized light when entering the bidirectional optical amplifier chip 2, and to control the principal value angle of the polarization angle of the amplified forward polarized light to be the same as that before amplification when entering the polarization beam splitting component 1; the first polarization control structure 11 and the second polarization control structure 12 respectively control the bidirectional optical amplifier chip 2 to perform low-noise amplification on any polarized light of the input optical amplifier by setting the first Faraday rotator 3 and the first wave plate 4, the second Faraday rotator 5 and the second wave plate 6 to rotate the polarization angle of the transmitted light.

[0063] The first wave plate 4 and the second wave plate 6 are set to rotate the polarization of the transmitted light at angles of γ and φ respectively, and the first Faraday rotator 3 is set to rotate the polarization of the transmitted light at angles of δ 1 The second Faraday rotator 5 rotates the polarization of the transmitted light by an angle of δ 2 The first polarization control structure 11 and the second polarization control structure 12 are respectively provided with the first Faraday rotator 3 and the first wave plate 4, the second Faraday rotator 5 and the second wave plate 6 to rotate the polarization angle of the transmitted light so that the following equations are all established:

[0064] 1δ 1 =δ 2 =1 / 4π+nm·π, n∈N 0 ;

[0065] 2γ=1 / 4π+n+m·π,n∈N 0 ,m∈N 0 ;

[0066] 3φ=3 / 4π+r+n·π,r∈N 0 , n∈N 0 .

[0067] The light transmission efficiency of the polarization beam splitter 1 is set to t 0 , the light transmission efficiency of the first polarization control structure 11 is t 1 , the light transmission efficiency of the second polarization control structure 12 is t 2 ; Set the bidirectional optical amplifier chip 2 to light gain g 0 ; Set the power of the input light to P In ; Set the input light to be divided into two orthogonal polarized lights with energies aP x ,bP y ; Set the power of the output light after the input light gain to P out ; Set the bidirectional optical amplifier chip 2 to the same polarization state of the forward input light and the reverse input light gain are g x , g y ; Set the gain of the optical amplifier for forward polarized light to be G x , G y ; Set the optical amplifier gain to G t ; The PDG is the polarization-dependent gain of the optical amplifier; the difference between the polarization rotation angle of the transmitted light and the polarization rotation angle in the ideal state is set to β 1 The optical amplifier controls the polarization angle of the input light by setting a polarization control structure to realize low PDG amplification of any polarized light by the optical amplifier, and the following equations are all established:

[0068] 1P In =a·P x +b·P y ;

[0069] 2P out =|cosβ 1 ∣·g x ·t 0 ·t 1 ·t 2 ·a·P x +|sin1 / 2π-β1 ∣·t 0 ·t 1 ·t 2 ·g y ·b·P y ;

[0070]

[0071] 5PDG=G y -G x =g y -g x ;

[0072] 6G t =G x =G y =|cosβ 1 ∣·g x ·t 0 ·t 1 ·t 2 , ifg y =g x .

[0073] The present invention adopts a polarization beam splitting component 1, a bidirectional optical amplifier chip 2, a Faraday rotator 3, a wave plate 4, a reflector, and a lens 8 as basic components, and the above basic components are designed in combination to form an optical amplifier, so that the SOA can achieve low noise and uniform gain for light of arbitrary polarization under relatively simple structure and process conditions, effectively reducing technical difficulty and R&D costs, shortening the process cycle, and having good market application prospects.

[0074] Embodiment 2: This embodiment provides an optical amplification method, including the optical amplifier described in Embodiment 1, comprising the following steps:

[0075] S1, using the polarization beam splitter 1 to split the light of arbitrary polarization into two polarized lights with orthogonal polarizations, wherein one of the light beams is transmitted through the first transmission optical path in the forward direction and then passes through the first polarization control structure 11, and the polarization angle increases by β 1 , β 1 ∈[0,1 / 2π]; another beam of light is transmitted through the second transmission optical path, and the polarization angle is reduced by 1 / 2π-β after passing through the second polarization control structure 12 in the reverse direction 1 , β 1 ∈[0,2π]; at this time, the polarization states of the two polarized lights are the same;

[0076] S2, the light transmitted by the first transmission optical path is polarized by the first polarization control structure 11, thereby controlling the polarization state of one of the polarized lights entering the bidirectional optical amplifier chip 2; the light transmitted by the second transmission optical path is polarized by the second polarization control structure 12, thereby controlling the polarization state of the other polarized light entering the bidirectional optical amplifier chip 2;

[0077] S3, the two beams of light are uniformly amplified by the bidirectional optical amplifier chip 2 and then transmitted from the other party's transmission optical path, that is, the light entering the bidirectional optical amplifier chip 2 through the first transmission optical path enters the second transmission optical path, and enters the polarization splitting component (1) after adjusting the polarization state again through the second control structure; the light entering the bidirectional optical amplifier chip 2 through the second transmission optical path enters the first transmission optical path, and enters the polarization splitting component 1 after adjusting the polarization state again through the first control structure; the two beams of polarized light are adjusted to be two beams of orthogonal polarized light perpendicular to the original polarization state;

[0078] S4, the polarization beam splitter 1 combines the two amplified polarized lights into one beam and outputs it from other ports.

[0079] There are multiple implementation methods for the design of the semiconductor optical amplifier, by changing the polarization rotation angle of the Faraday rotator and the wave plate, increasing the number of wave plates to control the polarization direction, and setting a reflector between each optical element to form a closed-loop optical path through phase reflection between the optical paths. The relationship between the polarization displacements of the three optical elements can be obtained from the above formula, and then the relationship between the first polarization control structure 11 and the second polarization control structure 12 to the polarization rotation angle of the transmitted light can be obtained.

[0080] Specifically, the Faraday rotator can rotate the polarization of forward light by a fixed angle, and rotate the polarization of light passing through it in the reverse direction by a fixed angle;

[0081] The wave plate can deflect the bidirectional polarization of light passing through it in the same direction by a fixed angle;

[0082] When the first wave plate 4 in the first polarization control structure 11 cooperates with the second wave plate 6 in the second polarization control structure 12, the polarization direction angle of the light passing through the first Faraday rotator 3 and the first wave plate 4 in the forward direction is f·π, f∈N0; and the polarization direction of the light passing through in the reverse direction will be 1 / 4π+f+gπ, f∈N 0 , g∈N 0 ;

[0083] When the second Faraday rotator 5 cooperates with the second wave plate 6, the polarization direction angle of the light passing through the second Faraday rotator 5 and the second wave plate 6 in the forward direction is m·π, m∈N0; and the polarization direction of the light passing through in the reverse direction is 1 / 2π+n·π, n∈N0;

[0084] The input light is split into two polarized lights with completely identical polarization directions before entering the bidirectional optical amplifier chip 2 .

[0085] The bidirectional optical amplifier chip 2 is used to amplify two input light beams with the same polarization direction with the same gain without degrading the gain and noise index indicators.

[0086] The output light from the bidirectional optical amplifier chip 2 passes through the second wave plate 6, the second Faraday rotator 5 and the first wave plate 4, the first Faraday rotator 3 respectively in sequence, and the polarization states of the two beams are adjusted to two output lights with orthogonal polarization directions.

[0087] In the two output light paths in the closed loop, the polarization direction of the output light from the first Faraday rotator 3 to the polarization beam splitter 1 cannot be transmitted through the polarization beam splitter 1 and is reflected.

[0088] Of the two output light beams in the closed loop, the polarization direction of the output light from the second Faraday rotator 5 to the polarization beam splitter 1 can now pass through the polarization beam splitter 1 and coincide with the path of the other polarized light beam, and are combined into one output light beam.

[0089] Example 3, please refer to Figure 3 Based on the embodiments 1 and 2, this embodiment provides an optical amplifier, comprising a polarization beam splitting component 1, a bidirectional optical amplifier chip 2 and a second reflector 7. The polarization beam splitting component 1 is equipped with a first reflector for reflecting the separated light beams; a lens 8 is provided on the bidirectional optical transmission end of the optical amplifier chip 2. The polarization control structure 11 and the polarization control structure 12 are attached to the polarization beam splitting component 1.

[0090] There are a first transmission optical path and a second transmission optical path between the polarization beam splitting component 1 and the bidirectional optical amplifier chip 2, and a second reflector 7 is arranged at the ends of the first transmission optical path and the second transmission optical path at the same time; the polarization beam splitting component is used to separate the non-polarized input light into two beams of light with orthogonal polarization; a first polarization control structure 11 is arranged on the first transmission optical path, and the first polarization control structure 11 includes a first Faraday rotator 3 and a first wave plate 4, and the first wave plate 4 is set to a 1 / 8 wave plate, that is, the first wave plate 4 has a deflection angle of 360°*1 / 8, that is, a deflection angle of 45°; the first polarization control structure 11 uses the Faraday rotator 3 to control the non-polarized state of the optical path The reversibility of the first wave plate 4 and the reverse reversibility of the optical path control the polarization state of the transmitted light; a second polarization control structure 12 is arranged on the second transmission optical path, and the second polarization control structure 12 includes a second Faraday rotator 5 and a second wave plate 6, and the second wave plate 6 is set as a 3 / 8 wave plate, that is, the second wave plate 6 has a deflection angle of 360°*3 / 8, that is, a deflection angle of 135°. The second polarization control structure 12 uses the non-reversibility of the second Faraday rotator 5 and the reverse reversibility of the second wave plate 6 to the optical path to control the polarization state of the transmitted light; the output light then passes through the polarization separation component 1 to combine the two amplified polarized lights into one beam of light and output it.

[0091] The first Faraday rotator 3 and the second Faraday rotator 5 are the same 1 / 8 Faraday rotator, which is attached to the end faces of the second port 14 and the third port 15 of the polarization beam splitting component 1, the second wave plate 6 is attached to the 1 / 8 Faraday rotator located in the second port 14 area, and the first wave plate 4 is attached to the 1 / 8 Faraday rotator located in the third port 15 area; the first port 13 of the polarization beam splitting component 1 is coupled with the 1 / 8 Faraday rotator, the second wave plate 6, the second reflector 7, the lens 8, the bidirectional optical amplifier chip 2, the lens 8, the first wave plate 4, and the third port 15 of the polarization beam splitting component 1 in sequence to form a closed-loop optical path.

[0092] The input light is split by the polarization beam splitting assembly 1 into two polarized lights with orthogonal polarization directions. The light output from the third port 15 is defined as polarized light one, and the light output from the second port 14 is defined as second polarized light. After the polarized light one is output from the third port 15, it passes through the 1 / 8 Faraday rotator and the second wave plate 4, and its polarization direction will be the same as the original polarization direction. After the second polarized light is output from the second port 14, it passes through the 1 / 8 Faraday rotator and the first wave plate 6, and its polarization direction will be perpendicular to the original polarization direction. At this time, the polarization directions of the first polarized light and the second polarized light are the same. The polarized light one and the polarized light two have the same polarization direction before entering the lens 8. After the second polarized light is reflected by the two triangular mirrors, it is refracted by the lens 8 and enters the bidirectional optical amplifier chip 2 to be amplified. After the second polarized light is output from the 1 / 8 wave plate, it is refracted by the lens 8 and enters the bidirectional optical amplifier chip 2 to be amplified. The amplified polarized light 1 is defined as the first polarized light, and the amplified polarized light 2 is defined as the second polarized light; the second polarized light is output from the bidirectional optical amplifier chip 2, passes through the lens 8, reaches the first wave plate 4, passes through the first wave plate 4 and the 1 / 8 Faraday rotator, and enters the polarization beam splitter component 1 from the third port 15, at which time the polarization direction is perpendicular to the polarization direction of the second polarized light; the second polarized light is output from the bidirectional optical amplifier chip 2, passes through the lens 8, and is reflected by two triangular mirrors to the second wave plate 6, and is adjusted in polarization direction by the second wave plate 6 and the 1 / 8 Faraday rotator, and then enters the polarization beam splitter component 1 from the second port 15. 4 enters the polarization beam splitter 1, at which time the polarization direction of the second polarized light is perpendicular to the polarization direction of the first polarized light; the polarization directions of the first polarized light and the second polarized light entering the polarization beam splitter 1 are perpendicular to each other; the polarization direction of the first polarized light cannot pass through the polarization beam splitter 1, and is output from the fourth port 16 after being reflected by the reflective surface on the polarization beam splitter; the polarization direction of the second polarized light can pass through the polarization beam splitter 1 and be output from the port 16; the path of the gain polarized first polarized light after being reflected completely overlaps with the gain polarized second polarized light, and they are combined into a beam of output light.

[0093] Example 4, please refer to Figure 4 Based on Example 3, this embodiment adds a third wave plate 9, and the third wave plate 9 is a 1 / 8 wave plate. The third wave plate 9 is attached to the fourth port 16 of the polarization beam splitting component, and can rotate the polarization state of the amplified light by 1 / 4π, thereby realizing polarization-maintaining amplification of the light.

[0094] Example 5, please refer to Figure 5 Based on Examples 1 and 2, this embodiment provides an optical amplifier, including a polarization beam splitting component 1, a bidirectional optical amplifier chip 2 and a second reflector 7. The polarization beam splitting component 1 is equipped with a first reflector 10 for reflecting the separated light beams; a lens 8 is provided on the bidirectional optical transmission end of the optical amplifier chip 2.

[0095] There are a first transmission optical path and a second transmission optical path between the polarization beam splitting component 1 and the bidirectional optical amplifier chip 2, and a second reflector 7 is arranged at the ends of the first transmission optical path and the second transmission optical path at the same time; the polarization beam splitting component is used to separate the non-polarized input light into two beams of light with orthogonal polarization; a first polarization control structure 11 is arranged on the first transmission optical path, and the first polarization control structure 11 includes a first Faraday rotator 3 and a first wave plate 4, and the first wave plate 4 is set to be a 1 / 8 wave plate, that is, the first wave plate 4 has a deflection angle of 360°*1 / 8, that is, a deflection angle of 45°; the first polarization control structure 11 uses the Faraday rotator 3 to control the non-polarized input light of the optical path. The second transmission optical path is provided with a second polarization control structure 12, which includes a second Faraday rotator 5 and a second wave plate 6. The second wave plate 6 is set as a 3 / 8 wave plate, that is, the second wave plate 6 has a deflection angle of 360°*3 / 8, that is, a deflection angle of 135°. The second polarization control structure 12 controls the polarization state of the transmitted light by utilizing the non-reversibility of the second Faraday rotator 5 and the reverse reversible characteristics of the second wave plate 6 to the optical path; the output light is then combined into one beam of light after the two amplified polarized lights through the polarization separation component 1 and output.

[0096] The first Faraday rotator 3 and the second Faraday rotator 5 are the same 1 / 8 Faraday rotator, which corresponds to the second port 14 and the third port 15 of the polarization beam splitter 1 at the same time. The second wave plate 6 is attached to the 1 / 8 Faraday rotator located in the area of ​​the second port 14, and the first wave plate 4 is attached to the 1 / 8 Faraday rotator located in the area of ​​the third port 15. The polarization control structure 11 and the polarization control structure 12 are fixed together. The second reflector 7 is composed of two triangular mirrors with a 90° reflection surface. The two triangular mirror reflection surfaces are arranged oppositely, so that the second reflector 7 has a 180° reflection surface. The first port 13 of the polarization beam splitter 1 is coupled with the 1 / 8 Faraday rotator, the second wave plate 6, the two triangular mirrors, the lens 8, the bidirectional optical amplifier chip 2, the lens 8, the first wave plate 4, and the third port 15 of the polarization beam splitter 1 in sequence to form a series optical path.

[0097] The input light is split by the polarization beam splitting assembly 1 into two polarized lights with orthogonal polarization directions. The light output from the third port 15 is defined as polarized light one, and the light output from the second port 14 is defined as second polarized light. After the polarized light one is output from the third port 15, it passes through the 1 / 8 Faraday rotator and the second wave plate 4, and its polarization direction will be the same as the original polarization direction. After the second polarized light is output from the second port 14, it passes through the 1 / 8 Faraday rotator and the first wave plate 6, and its polarization direction will be perpendicular to the original polarization direction. At this time, the polarization directions of the first polarized light and the second polarized light are the same. The polarized light one and the polarized light two have the same polarization direction before entering the lens 8. After the second polarized light is reflected by the two triangular mirrors, it is refracted by the lens 8 and enters the bidirectional optical amplifier chip 2 to be amplified. After the second polarized light is output from the 1 / 8 wave plate, it is refracted by the lens 8 and enters the bidirectional optical amplifier chip 2 to be amplified. The amplified polarized light 1 is defined as the first polarized light, and the amplified polarized light 2 is defined as the second polarized light; the second polarized light is output from the bidirectional optical amplifier chip 2, passes through the lens 8, reaches the first wave plate 4, passes through the first wave plate 4 and the 1 / 8 Faraday rotator, and enters the polarization beam splitter component 1 from the third port 15, at which time the polarization direction is perpendicular to the polarization direction of the second polarized light; the second polarized light is output from the bidirectional optical amplifier chip 2, passes through the lens 8, and is reflected by two triangular mirrors to the second wave plate 6, and is adjusted in polarization direction by the second wave plate 6 and the 1 / 8 Faraday rotator, and then enters the polarization beam splitter component 1 from the second port 15. 4 enters the polarization beam splitter 1, at which time the polarization direction of the second polarized light is perpendicular to the polarization direction of the first polarized light; the polarization directions of the first polarized light and the second polarized light entering the polarization beam splitter 1 are perpendicular to each other; the polarization direction of the first polarized light cannot pass through the polarization beam splitter 1, and is output from the fourth port 16 after being reflected by the reflective surface on the polarization beam splitter; the polarization direction of the second polarized light can pass through the polarization beam splitter 1 and be output from the port 16; the path of the gain polarized first polarized light after being reflected completely overlaps with the gain polarized second polarized light, and they are combined into a beam of output light.

[0098] In summary, the present invention adopts polarization beam splitting component 1, optical amplifier chip 2, Faraday rotator, wave plate, reflector, and lens 8 as basic components, and the above basic components are designed to form an optical amplifier, so that SOA can achieve low noise and uniform gain for light of arbitrary polarization under relatively simple structure and process conditions, effectively reducing technical difficulty and R&D cost, reducing process cycle, and having good market application prospects; the present invention adjusts the polarization direction of light through the polarization beam splitting component 1 in conjunction with the first polarization control structure 11 and the second polarization control structure 12, splits the input light into two beams of light with different polarization directions, amplifies them separately, and then combines them into one beam of light for output, so that the semiconductor optical amplifier can amplify any polarized light, and achieve the low noise and arbitrary polarization gain effect of the semiconductor optical amplifier. The amplified light will be adjusted to a beam of output light by the polarization control structure and the polarization beam splitting component again, effectively improving the amplification effect of light. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0099] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An optical amplifier, characterized in that: The invention comprises a polarization beam splitting component (1) and a bidirectional optical amplifier chip (2); a first transmission optical path and a second transmission optical path exist between the polarization beam splitting component (1) and the bidirectional optical amplifier chip (2); a first polarization control structure (11) is provided on the first transmission optical path, and a second polarization control structure (12) is provided on the second transmission optical path; the first polarization control structure (11) comprises a first Faraday rotator (3) and a first wave plate (4); the second polarization control structure (12) comprises a second Faraday rotator (5) and a second wave plate (6); The polarization beam splitting component (1) is provided with a first port (13), a second port (14), a third port (15), and a fourth port (16); the first port (13) is used to receive incident light; the second port (14) is used to output one of two input light beams with orthogonal polarization directions and transmit the light to the first polarization control structure (11); the third port (15) is used to output the other of the two input light beams with orthogonal polarization directions and transmit the light to the second polarization control structure (12); and the fourth port (16) is used to output amplified light; The second port (14) of the polarization beam splitting component, the first polarization control structure (11), the bidirectional optical amplifier chip (2), the polarization control structure (12), and the third port (15) of the polarization beam splitting component (1) are combined to form a series optical path.

2. The optical amplifier according to claim 1, characterized in that: The polarization beam splitter component (1) outputs two beams of polarized light having orthogonal polarization states, one of which enters the series optical path from the second port (14) in the forward direction, is amplified and polarization-adjusted, and then enters the polarization beam splitter component (1) from the third port (15); and the other polarized light enters the series optical path from the third port (15) in the reverse direction, is amplified and polarization-adjusted, and then enters the polarization beam splitter component (1) from the second port (14).

3. The optical amplifier according to claim 1 is characterized in that: A second reflector (7) is arranged between the second polarization control structure (12) and the bidirectional optical amplifier chip (2); the second reflector (7) is composed of two triangular mirrors with 90° reflective surfaces, and the two triangular mirror reflective surfaces are arranged opposite to each other, so that the second reflector (7) has a 180° reflective surface, thereby realizing light transmission between the second polarization control structure (12) and the bidirectional optical amplifier chip; a first reflector (10) is arranged between the polarization beam splitting component (1) and the second polarization control structure (12), and the first reflector (10) has a 90° reflective surface, and is used to realize light transmission between the polarization beam splitting component (1) and the second polarization control structure (12).

4. The optical amplifier according to claim 1 is characterized in that: Lenses (8) are provided on both the first transmission optical path and the second transmission optical path, and the lenses (8) are distributed at the bidirectional optical transmission end of the bidirectional optical amplifier chip (2).

5. The optical amplifier according to claim 1 is characterized in that: The first polarization control structure (11) is used to control the polarization state of light on the first transmission optical path, so as to output forward polarized light from the second port (14) and output reverse polarized light from the third port (15); the forward polarized light remains polarized when passing through the first polarization control structure (11), and the reverse polarized light has a polarization angle reduced by 1 / 2π+gπ (g∈N0); The first polarization control structure (11) is used to control the polarization state of light on the first transmission optical path. After the forward polarized light output from the second port (14) passes through the first polarization control structure (11), the polarization remains unchanged, and the main value angle of the polarization angle of the amplified reverse polarized light when entering the second port (14) is controlled to be the same as the main value angle of the polarization angle when output from the third port (15); the second polarization control structure (12) is used to control the polarization state of light on the second transmission optical path. The polarization angle of light passing through the second polarization control structure (12) in the forward direction increases by π+kπ (k∈N0), and the polarization angle of light passing through the second polarization control structure (12) in the reverse direction increases by 1 / 2π+gπ (g∈N0); The second polarization control structure is used to control the reverse polarized light output from the third port (15) to have a polarization angle that is the same as that of the forward polarized light when entering the bidirectional optical amplifier chip (2), and to control the forward polarized light after being amplified to have a principal value angle of the polarization angle that is the same as that before being amplified when entering the polarization beam splitting component (1); The first polarization control structure (11) and the second polarization control structure (12) respectively control the bidirectional optical amplifier chip (2) to perform low-noise amplification on any polarized light of the input optical amplifier by arranging the first Faraday rotator (3) and the first wave plate (4), the second Faraday rotator (5) and the second wave plate (6) to rotate the polarization angle of the transmitted light.

6. The optical amplifier according to claim 5, characterized in that: The first wave plate (4) and the second wave plate (6) are set to rotate the polarization of the transmitted light at angles γ and φ respectively, the first Faraday rotator (3) is set to rotate the polarization of the transmitted light at angles δ1, and the second Faraday rotator (5) is set to rotate the polarization of the transmitted light at angles δ2; The first polarization control structure (11) and the second polarization control structure (12) are respectively provided with a first Faraday rotator (3) and a first wave plate (4), a second Faraday rotator (5) and a second wave plate (6) to rotate the polarization angle of the transmitted light so that the following equations are all established: (1) δ1=δ2=1 / 4π+(nm) ·π, n∈N0; (2)γ=1 / 4π+(n+m)·π, n∈N0, m∈N0; (3)φ=3 / 4π+(r+n)·π, r∈N0, n∈N0.

7. The optical amplifier according to claim 6, characterized in that: The light transmission efficiency of the polarization beam splitting component (1) is set to t0, the light transmission efficiency of the first polarization control structure (11) is set to t1, and the light transmission efficiency of the second polarization control structure (12) is set to t2; the light gain of the bidirectional optical amplifier chip (2) is set to g0; and the power of the input light is set to P In ; Set the input light to be divided into two orthogonal polarized lights with energies aP x ,bP y ; Set the power of the output light after the input light gain to P out ; Set the gains of the bidirectional optical amplifier chip (2) for the forward input light and the reverse input light in the same polarization state to be g respectively x , g y ; Set the gain of the optical amplifier for forward polarized light to be G x , G y ; Set the optical amplifier gain to G t ; The PDG is the polarization-dependent gain of the optical amplifier; the difference between the polarization rotation angle of the transmitted light and the polarization rotation angle in the ideal state of the polarization control structure is set to β1; The optical amplifier controls the polarization angle of the input light by setting a polarization control structure to achieve low PDG amplification of any polarized light by the optical amplifier, and the following equations are all established: (1)P In =a·P x +b·P y ; (2)P out =∣cosβ1∣·g x ·t0·t1·t2·a·P x +∣sin(1 / 2π-β1)∣·t0·t1·t2·g y ·b·P y ; (3) (4) (5)PDG=G y -G x =g y -g x ; (6)G t =G x =G y =∣cosβ1∣·g x ·t0·t1·t2,ifg y =g x。 8. A method for optical amplification, comprising the optical amplifier according to any one of claims 1 to 7, characterized in that: The steps include: S1. Use a polarization beam splitter (1) to split light of arbitrary polarization into two polarized lights with orthogonal polarizations, wherein one light beam is transmitted through a first transmission optical path and passes through a first polarization control structure (11) in the forward direction, and the polarization angle increases by β1, β1∈[0,1 / 2π]; the other light beam is transmitted through a second transmission optical path and passes through a second polarization control structure (12) in the reverse direction, and the polarization angle decreases by 1 / 2π-β1, β1∈[0,2π]; at this time, the polarization states of the two polarized lights are the same; S2, the light transmitted by the first transmission optical path is polarized by the first polarization control structure (11), thereby controlling the polarization state of one of the polarized lights entering the bidirectional optical amplifier chip (2); the light transmitted by the second transmission optical path is polarized by the second polarization control structure (12), thereby controlling the polarization state of another polarized light entering the bidirectional optical amplifier chip (2); S3, after being uniformly gain-amplified by the bidirectional optical amplifier chip (2), the two light beams are transmitted from the other party's transmission optical path, that is, the light that enters the bidirectional optical amplifier chip (2) through the first transmission optical path enters the second transmission optical path, and then enters the polarization splitting component (1) after adjusting the polarization state again through the second control structure; the light that enters the bidirectional optical amplifier chip (2) through the second transmission optical path enters the first transmission optical path, and then enters the polarization splitting component (1) after adjusting the polarization state again through the first control structure; the two polarized light beams are adjusted to be two orthogonal polarized light beams that are perpendicular to the original polarization state; S4, the polarization beam splitter (1) combines the two amplified polarized light beams into one beam and outputs it from other ports.

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