An optical amplifier and transmission system

Abstract

The embodiment of the present disclosure provides an optical amplifier and a transmission system, the optical amplifier comprises a coupling input module, a multiplexing module, an amplification module, a demultiplexing module and a coupling output module; wherein the coupling input module is used for receiving a fundamental mode pumping light and a fundamental mode signal light, and outputting to the multiplexing module; the multiplexing module is used for mode conversion on the fundamental mode pumping light, obtaining a non-fundamental mode pumping light, and coupling the non-fundamental mode pumping light with the fundamental mode signal light and outputting to the amplification module; the amplification module is used for amplifying the fundamental mode signal light; the demultiplexing module is used for decoupling the non-fundamental mode pumping light and the amplified fundamental mode signal light and outputting to the coupling output module.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic integrated devices, and more particularly to an optical amplifier and transmission system. Background Technology

[0002] Optical amplifiers are indispensable components in silicon photonics communication systems, playing a crucial role in amplifying optical signals and compensating for losses. However, it is difficult for optical amplifiers in related technologies to simultaneously achieve miniaturization and high gain. Summary of the Invention

[0003] In view of this, embodiments of the present disclosure provide an optical amplifier and a transmission system.

[0004] To achieve the above objectives, the technical solution disclosed herein is implemented as follows:

[0005] In a first aspect, embodiments of this disclosure provide an optical amplifier, comprising: a coupling input module, a multiplexing module, an amplification module, a demultiplexing module, and a coupling output module; wherein, the coupling input module is used to receive a fundamental mode pump light and a fundamental mode signal light, and output them to the multiplexing module; the multiplexing module is used to perform mode conversion on the fundamental mode pump light to obtain a non-fundamental mode pump light, and couple the non-fundamental mode pump light with the fundamental mode signal light before outputting it to the amplification module; the amplification module is used to amplify the fundamental mode signal light; the demultiplexing module is used to decouple the non-fundamental mode pump light from the amplified fundamental mode signal light before outputting it to the coupling output module.

[0006] In some embodiments, the multiplexing module includes a first input waveguide, a first coupling waveguide, and a first output waveguide;

[0007] The first coupled waveguide includes a first waveguide and a second waveguide arranged parallel to each other; the effective refractive index neff1 of the pump light transmitted in the first waveguide and the effective refractive index neff2 of the pump light transmitted in the second waveguide satisfy the phase matching condition: neff1(W i ) = neff2(W j ); where W i W is the width of the first waveguide. j The width of the second waveguide is given.

[0008] In some embodiments, the demultiplexing module includes a second input waveguide, a second coupling waveguide, and a second output waveguide; the second coupling waveguide includes a fifth waveguide and a sixth waveguide arranged parallel to each other; the effective refractive index neff3 of the pump light transmitted in the fifth waveguide and the effective refractive index neff4 of the pump light transmitted in the sixth waveguide satisfy the phase matching condition: neff3(W m ) = neff4(Wn ); where W m W is the width of the fifth waveguide. n The width of the sixth waveguide.

[0009] In some embodiments, the structure of the second coupled waveguide is the same as that of the first coupled waveguide.

[0010] In some embodiments, the amplification module includes a substrate, an oxide layer, a ridge gain layer, and a waveguide cladding covering the ridge gain layer;

[0011] The ridge-shaped gain layer is doped with rare earth ions, and the material of the ridge-shaped gain layer includes silicon nitride or lithium niobate.

[0012] In some embodiments, the waveguide size of the amplification module is determined based on the overlap factor η between the corrected light intensity and the erbium ions. total Adjustments are made; where η total =Γ×η p,s , ψ p,s For the intensity distribution of the pump light and the signal light, n i (x,y) represents the doping distribution of erbium ions at energy level i. The normalized transverse intensity distribution of the signal light in TE0 mode. The normalized transverse intensity distribution of the pump light in TE1 mode is given by A, where A is the cross-sectional dimension of the ridge gain layer.

[0013] In some embodiments, the waveguide dimensions of the amplification module include the length of the ridge gain layer and the cross-sectional dimensions of the ridge gain layer, wherein the cross-sectional dimensions of the ridge gain layer include the width and height of the ridge gain layer.

[0014] In some embodiments, the coupling input module and the coupling output module include one or more of a mode converter, a grating coupler, and an array coupler.

[0015] In a second aspect, embodiments of this disclosure provide a transmission system comprising the optical amplifier described in any of the first aspects.

[0016] This disclosure provides an optical amplifier and a transmission system. The optical amplifier includes a coupling input module, a multiplexing module, an amplification module, a demultiplexing module, and a coupling output module. The coupling input module receives a fundamental mode pump light and a fundamental mode signal light, and outputs them to the multiplexing module. The multiplexing module performs mode conversion on the fundamental mode pump light to obtain a non-fundamental mode pump light, and couples the non-fundamental mode pump light with the fundamental mode signal light before outputting it to the amplification module. The amplification module amplifies the fundamental mode signal light. The demultiplexing module decouples the non-fundamental mode pump light from the amplified fundamental mode signal light before outputting it to the coupling output module. This disclosure utilizes the coupling mode principle to achieve efficient coupling between the pump light and the signal light through the multiplexing module of the optical amplifier. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an optical amplifier provided in one embodiment of the present disclosure;

[0018] Figure 2 This is a schematic diagram of a reuse module provided in an embodiment of the present disclosure;

[0019] Figure 3 Mode field distribution diagrams of pump light and signal light under different modes provided in an embodiment of this disclosure;

[0020] Figure 4 This is a schematic diagram of a demultiplexing module provided in an embodiment of the present disclosure;

[0021] Figure 5 A cross-sectional schematic diagram of an enlarged module provided in an embodiment of this disclosure;

[0022] Figure 6 Simulation curve of the gain of an optical amplifier as a function of waveguide length, provided in an embodiment of this disclosure. Detailed Implementation

[0023] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0024] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of this disclosure. However, it will be apparent to those skilled in the art that this disclosure may be practiced without one or more of these details. In other instances, to avoid confusion with this disclosure, certain technical features well-known in the art have not been described; that is, not all features of actual embodiments are described herein, nor are well-known functions and structures described in detail.

[0025] In the accompanying drawings, for clarity, the dimensions of layers, areas, and elements, as well as their relative dimensions, may be exaggerated. The same reference numerals denote the same elements throughout.

[0026] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this disclosure, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this disclosure.

[0027] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprise” and / or “comprising,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0029] To fully understand this disclosure, detailed steps and structures will be presented in the following description to illustrate the technical solutions of this disclosure. Preferred embodiments of this disclosure are described in detail below; however, other embodiments may also be implemented in addition to these detailed descriptions.

[0030] Figure 1 This is a schematic diagram of an optical amplifier provided in an embodiment of the present disclosure, with reference to... Figure 1 The optical amplifier includes: a coupling input module 110, a multiplexing module 120, an amplification module 130, a demultiplexing module 140, and a coupling output module 150; wherein, the coupling input module 110 is used to receive fundamental mode pump light and fundamental mode signal light, and output them to the multiplexing module 120; the multiplexing module 120 is used to perform mode conversion on the fundamental mode pump light to obtain non-fundamental mode pump light, and couple the non-fundamental mode pump light with the fundamental mode signal light before outputting it to the amplification module 130; the amplification module 130 is used to amplify the fundamental mode signal light; the demultiplexing module 140 is used to decouple the non-fundamental mode pump light from the amplified fundamental mode signal light before outputting it to the coupling output module 150.

[0031] In this embodiment of the disclosure, the coupling input module 110 and the coupling output module 150 can realize end-face coupling between off-chip optical fibers and on-chip waveguides.

[0032] In this embodiment, the coupling input module 110 includes a pump light end-face coupling module 111 for receiving pump light from the pump light input module; and a signal light end-face coupling module 112 for receiving signal light from the signal light input module. Here, the signal light input module generates signal light and transmits it to the signal light end-face coupling module 112, and the pump light input module generates pump light and transmits it to the pump light end-face coupling module 111.

[0033] In some embodiments, the pump light input module uses a laser with a wavelength of 980 nanometers to emit pump light. The signal light input module uses a laser with a wavelength of 1550 nanometers to emit signal light. In other embodiments, the pump light input module may also use a laser with a wavelength of 1480 nanometers to emit pump light.

[0034] In this embodiment of the disclosure, the coupling input module 110 and the coupling output module 150 include one or more of the following: a mode converter, a grating coupler, and an array coupler.

[0035] In this embodiment of the disclosure, the fundamental mode pump light and fundamental mode signal light received by the coupling input module 110 can be collectively referred to as fundamental mode input light. The fundamental mode signal light is used to carry information, and the fundamental mode pump light is used to provide amplification energy. Specifically, the fundamental mode signal light is a signal light in TE0 mode; the fundamental mode pump light is a pump light in TE0 mode, where TE stands for transverse electric field mode, and TE0 mode is the transverse electric field fundamental mode.

[0036] In this embodiment of the disclosure, the multiplexing module 120 is used to perform mode conversion on the fundamental mode pump light to obtain a non-fundamental mode pump light. In a specific example, the multiplexing module 120 is used to perform mode conversion on the TE0 mode pump light to obtain the TE1 mode pump light. The TE1 mode is a first-order transverse electric field mode.

[0037] In this embodiment of the disclosure, the coupling output module 150 includes a pump light output module 151 for outputting pump light; and a signal light output module 152 for outputting amplified signal light. Specifically, the signal light output module 152 is used to output amplified fundamental mode signal light.

[0038] Continue to refer to Figure 1 The optical amplifier also includes a substrate 160 and an oxide layer 170. The waveguide structure of the optical amplifier is formed on the oxide layer 170 and covered by a waveguide cladding (not shown in the figure). In this embodiment, the substrate 160 can be a single-element semiconductor material substrate, such as a silicon (Si) substrate, a germanium (Ge) substrate, a composite semiconductor material substrate, such as a germanium-silicon (SiGe) substrate, or a silicon-on-insulator (SOI) substrate, a germanium-on-insulator (GeOI) substrate, etc. This embodiment uses a silicon substrate as an example. In this embodiment, the oxide layer 170 is made of low-refractive-index silicon dioxide. The oxide layer is located between the waveguide structure and the substrate, which can reduce leakage light flowing from the waveguide structure to the substrate 160 and also protect the entire device.

[0039] Figure 2 This is a schematic diagram of a reuse module provided in an embodiment of the present disclosure, with reference to... Figure 2The multiplexing module includes a first input waveguide 210, a first coupling waveguide 220, and a first output waveguide 230; the first coupling waveguide 220 includes a first waveguide 221 and a second waveguide 222 arranged parallel to each other. Along the light transmission direction, the pump light passes sequentially through the first input waveguide 210, the first waveguide 221, the second waveguide 222, and the first output waveguide 230.

[0040] In this embodiment, the first input waveguide 210 includes a third waveguide 211 and a fourth waveguide 212. Both the third and fourth waveguides are single-mode waveguides. The third waveguide 211 receives TEO mode pump light, and the fourth waveguide 212 receives TEO mode signal light. The third waveguide 211 is suitable for single-mode input at a wavelength of 980 nm, and the fourth waveguide 212 is suitable for single-mode input at a wavelength of 1550 nm.

[0041] In this embodiment of the present disclosure, the first waveguide 221 is a tapered waveguide whose width gradually decreases along the direction of light transmission, and the second waveguide 222 is a tapered waveguide whose width gradually increases along the direction of light transmission.

[0042] In this embodiment, the first output waveguide 230 is a multimode waveguide used to output a multimode beam. The multimode beam is a beam obtained by coupling TE1 mode pump light and TE0 mode signal light.

[0043] In this embodiment, the coupling mode principle is utilized to achieve efficient coupling between pump light and signal light through the multiplexing module of the optical amplifier.

[0044] In this embodiment of the present disclosure, the first waveguide 221 and the second waveguide 222 are arranged in parallel to each other, and there is a first preset distance between the first waveguide 221 and the second waveguide 222, which is a fixed value.

[0045] In this embodiment of the disclosure, the effective refractive index neff1 of the pump light transmitted in the first waveguide 221 and the effective refractive index neff2 of the pump light transmitted in the second waveguide 222 satisfy the phase matching condition: neff1(W i ) = neff2(W j ); where W i W is the width of the first waveguide 221. jLet neff1 be the width of the second waveguide 222. In a specific example, neff1 represents the effective refractive index of the TE0 mode pump light input to the first waveguide 221, and neff2 represents the effective refractive index of the TE1 mode pump light input to the second waveguide 222. Since the effective refractive index neff1 of the pump light transmitted in the first waveguide 221 and the effective refractive index neff2 of the pump light transmitted in the second waveguide 222 are equal, satisfying the phase matching condition, the pump light in the first waveguide 221 and the second waveguide 222 are coupled to each other. The TE0 mode pump light in the first waveguide 221 is coupled into the second waveguide 222 and converted into TE1 mode pump light, realizing the mode conversion from TE0 mode pump light to TE1 mode pump light. The converted TE1 mode pump light is output from the first output waveguide 230. Since the signal light transmitted in the first waveguide 221 and the signal light transmitted in the second waveguide 222 are in a state where the phase matching condition is not met, the TE0 mode signal light in the second waveguide 222 will not couple with the first waveguide 221. Therefore, the TE0 mode signal light is directly output from the first output waveguide 230 with minimal loss. That is, the TE0 mode signal light passes through the fourth waveguide 212, the second waveguide 222, and the first output waveguide 230 in sequence.

[0046] Since the effective refractive index of the pump light of the TE0 mode in the first waveguide 221 varies with the width W i The effective refractive index of the pump light of the TE1 mode in the second waveguide 222 changes with the width W. j The width settings of the first waveguide 221 and the second waveguide 222 also need to meet the phase matching condition due to the changes.

[0047] In this embodiment of the disclosure, the multiplexing module is also used to couple the pump light of TE1 mode and the signal light of TE0 mode to the same waveguide (first output waveguide 230) and output it to the amplification module for amplification of the signal light of TE0 mode.

[0048] Figure 3 The mode field distribution diagrams of pump light and signal light under different modes provided in an embodiment of this disclosure are shown below. Figure 3 (A) shows the mode field distribution of the pump light with a wavelength of 980 nm in TE0 mode; (B) shows the mode field distribution of the pump light with a wavelength of 980 nm in TE1 mode; and (C) shows the mode field distribution of the signal light with a wavelength of 1550 nm in TE0 mode. (Combined with...) Figure 2 and Figure 3 The mode field distribution of the pump light in the TE0 mode received by the third waveguide 211 can be referenced. Figure 3 In (A), the mode field distribution of the signal light receiving the TEO mode in the fourth waveguide 212 can be referenced. Figure 3 (C) in the middle.

[0049] Figure 4 This is a schematic diagram of a demultiplexing module provided in an embodiment of this disclosure, with reference to... Figure 4 The demultiplexing module includes a second input waveguide 310, a second coupling waveguide 320, and a second output waveguide 330. The second coupling waveguide 320 includes a fifth waveguide 321 and a sixth waveguide 322 arranged parallel to each other. Along the light transmission direction, the pump light passes sequentially through the second input waveguide 310, the sixth waveguide 322, the fifth waveguide 321, and the second output waveguide 330. The second input waveguide 310 is a multimode waveguide used to input non-fundamental mode pump light and amplified fundamental mode signal light.

[0050] In this embodiment, the fifth waveguide 321 and the sixth waveguide 322 are arranged parallel to each other, and there is a second preset distance between the fifth waveguide 321 and the sixth waveguide 322, which is a fixed value. In some embodiments, the first preset distance and the second preset distance are equal.

[0051] In this embodiment of the disclosure, the effective refractive index neff3 of the pump light transmitted in the fifth waveguide 321 and the effective refractive index neff4 of the pump light transmitted in the sixth waveguide 322 satisfy the phase matching condition: neff3(W m ) = neff4(W n ); where W m W is the width of the fifth waveguide 321. n Let neff3 be the width of the sixth waveguide 322. In a specific example, neff3 represents the effective refractive index of the TE0 mode pump light input to the fifth waveguide 321, and neff4 represents the effective refractive index of the TE1 mode pump light input to the sixth waveguide 322. Since the effective refractive index neff3 of the pump light transmitted in the fifth waveguide 321 and the effective refractive index neff4 of the pump light transmitted in the sixth waveguide 322 are equal, satisfying the phase matching condition, the pump light in the sixth waveguide 322 couples with the fifth waveguide 321. The TE1 mode pump light in the sixth waveguide 322 is coupled into the fifth waveguide 321 and converted into the TE0 mode pump light, realizing the mode conversion from the TE1 mode pump light to the TE0 mode pump light. The converted TE0 mode pump light is output from the second output waveguide 330. Because the signal light transmitted in the fifth waveguide 321 and the signal light transmitted in the sixth waveguide 322 are in a state where the phase matching condition is not met, the amplified TE0 mode signal light in the sixth waveguide 322 will not couple with the fifth waveguide 321. Therefore, the amplified TE0 mode signal light is directly output from the second output waveguide 330 with minimal loss. That is, the amplified TE0 mode signal light passes through the second input waveguide 310, the sixth waveguide 322, and the second output waveguide 330 in sequence.

[0052] In this embodiment of the disclosure, the second output waveguide 330 includes a seventh waveguide 331 and an eighth waveguide 332. The seventh waveguide 331 and the eighth waveguide 332 are single-mode waveguides. The seventh waveguide 331 is used to output pump light in TEO mode, and the eighth waveguide 332 is used to output amplified signal light in TEO mode.

[0053] In this embodiment, the structure of the second coupled waveguide is the same as that of the first coupled waveguide. In some embodiments, the material of the second coupled waveguide is the same as that of the first coupled waveguide.

[0054] Since the effective refractive index of the pump light of the TE0 mode in the fifth waveguide 321 varies with the width W m The effective refractive index of the pump light in the TE1 mode in waveguide 322 changes with the width W. n Therefore, the width settings of the fifth waveguide 321 and the sixth waveguide 322 must also meet the phase matching condition.

[0055] In this embodiment of the disclosure, the demultiplexing module is further used to decouple the amplified TEO mode signal light from the pump light, thereby filtering out the amplified TEO mode signal light and outputting it from the eighth waveguide 332. Combined with... Figure 3 and Figure 4 The mode field distribution of the TE0 mode pump light output from the seventh waveguide 331 can be referenced. Figure 3 In (A), the mode field distribution of the TE0 mode signal light output from the eighth waveguide 332 can be referenced. Figure 3 (C) in the middle.

[0056] The multiplexing and demultiplexing modules provided in this disclosure have simple structures, are easy to manufacture, and are compatible with existing finished optical fibers, exhibiting high adaptability. Furthermore, the multiplexing and demultiplexing modules can be asymmetric coupling structures, which effectively improves process tolerance, solves the problems of off-chip bundling and high coupling loss, and promotes the high integration of optical amplifiers.

[0057] Figure 5 This is a cross-sectional schematic diagram of an enlarged module provided in an embodiment of the present disclosure, with reference to... Figure 5 The amplification module includes: a substrate 410, an oxide layer 420, a ridge gain layer 430, and a waveguide cladding 440 covering the ridge gain layer 430; wherein, the oxide layer 420 covers the substrate 410; the ridge gain layer 430 is located on the oxide layer 420; and the waveguide cladding 440 covers both the ridge gain layer 430 and the oxide layer 420. It should be understood that, in order to clearly show each layer structure in the figure, the dimensional proportions of each layer structure may not conform to the actual structure. Here, Figure 5 The cross-section shown is the cross-section along the direction of light transmission.

[0058] In this embodiment, the materials of the substrate 410 and the oxide layer 420 can refer to those described above. Figure 1 The description of substrate 160 and oxide layer 170 is provided below, and for the sake of brevity, it will not be repeated here. Oxide layer 420 is located between ridge gain layer 430 and substrate 410, which can reduce the leakage light flowing from ridge gain layer 430 to substrate 410 and play a protective role for the entire device.

[0059] In this embodiment, the ridge gain layer 430 is doped with rare earth ions, and the material of the ridge gain layer 430 includes silicon nitride, lithium niobate, or tantalum oxide. In some embodiments, the rare earth ions are erbium ions or a combination of erbium ions and ytterbium ions. This embodiment uses lithium niobate as an example of the material of the ridge gain layer 430. Here, erbium-doped lithium niobate material deposited by atomic layer deposition can be used as the ridge gain layer 430, which can provide a larger concentration of photoactive erbium and better film quality; by dispersing erbium ions by adding ytterbium ions, the cooperative upconversion coefficient of erbium ions can be reduced.

[0060] In some embodiments, refer to Figure 5 In the cross-section of the ridge gain layer 430 along the light transmission direction, its ridge is a trapezoid with a base width greater than its top width. That is, the ridge width near the center line of the ridge gain layer 430 is smaller than the ridge width away from the center line of the ridge gain layer 430. In some embodiments, due to the anisotropy of etching rate in the waveguide fabrication process, the waveguide sidewalls are not perpendicular after processing, and the trapezoidal cross-section of the ridge gain layer 430 is formed by the etching angle. Optionally, a common etching angle can be 80°.

[0061] In this embodiment, the ridge gain layer 430 has an X-cut Y-transmission structure. To illustrate the X-cut Y-transmission structure, we first define xyz (lowercase letters) to represent the Cartesian coordinate system, and XYZ (uppercase letters) to represent the crystal axes of the ridge gain layer 430 (lithium niobate). Here, the X-axis of the ridge gain layer 430 is perpendicular to the substrate surface, which is called "X-cut". If the angle between the z-axis of the Cartesian coordinate system and the Y-axis of the ridge gain layer 430 is 0°, the waveguide propagates along the Y-axis, which is called "Y-transmission". Together, they form "X-cut Y-transmission".

[0062] In this embodiment, the pump light is used to provide amplification energy. When the pump light of the TE1 mode passes through the amplification module, the ridge gain layer 430 in the amplification module absorbs the pump light of the TE1 mode. The rare earth elements in the ridge gain layer 430 absorb the energy of photons, causing the electrons around the atoms of the element to transition from a low energy level to a high energy level. When the electrons around the atoms in the ridge gain layer 430 transition from a high energy level to a low energy level, they release energy in the form of photons. When the signal light of the TEO mode passes through the amplification module, it absorbs the energy released by the electron transition of the above-mentioned elements, thereby realizing the amplification of the signal light of the TEO mode.

[0063] In this embodiment, the overlap factor is a parameter used to describe the degree of overlap between the fundamental mode and the ridge gain layer 430 in the optical waveguide. It is crucial for determining the performance and optimizing the design of the optical amplifier. In an optical amplifier, a larger overlap factor indicates a larger effective interaction area between the fundamental mode and the ridge gain layer 430, meaning more optical field energy is absorbed and amplified by the gain medium. This helps improve the gain and output power of the optical amplifier. By optimizing the structural design parameters of the amplification module, the degree of overlap between the fundamental mode and the ridge gain layer 430 can be adjusted, thereby obtaining better amplification performance.

[0064] In this embodiment of the disclosure, the waveguide dimensions of the amplification module are adjusted according to the following formula: η total =Γ×η p,s ;in, ψ p,s For the intensity distribution of the pump light and the signal light, n i (x,y) represents the doping distribution of erbium ions at energy level i. The normalized transverse intensity distribution of the signal light in TE0 mode. The normalized transverse intensity distribution of the pump light in TE1 mode is given by A, where A is the cross-sectional dimension of the ridge gain layer.

[0065] In this embodiment, the waveguide size design optimization of the amplification module needs to consider the influence of the cross-sectional size of the ridge gain layer and the overlap factor between light intensity and erbium ions on the gain. The cross-sectional size of the ridge gain layer affects the absorption and transition probabilities of pump light and signal light at low and high energy levels, thus affecting the gain. Simultaneously, the inversion particle number of erbium ions is related to the mode field distribution of the pump light, and the mode field distributions of the pump light and signal light affect the amplifier gain. Therefore, it is necessary to introduce the overlap factor Γ of the mode field distributions of the TE1 mode pump light and the TEO mode signal light on the overlap factor η between light intensity and erbium ions. p,s After correction, the overlap factor is η. total .

[0066] On the other hand, the erbium ion concentration, width, and height of the ridge gain layer can be adjusted according to the mode field distribution and gain of different waveguide modes. In summary, the cross-sectional dimensions of the ridge gain layer enable the pump and signal light in the ridge gain layer to have higher confinement factors and higher pump and signal overlap factors, thereby providing sufficient gain and lower waveguide loss.

[0067] Figure 6 This is a simulation curve showing the gain of an optical amplifier as a function of waveguide length, provided in one embodiment of this disclosure. It should be noted that... Figure 6 With an erbium ion doping concentration of 10 in the ridge gain layer 26 cm -3 The following explanation uses a ridge gain layer with a width of 1.2 mm as an example. Figure 6 The diagram illustrates the relationship between gain and waveguide length for pump powers of 20mW, 40mW, 100mW, 200mW, and 300mW. (Refer to...) Figure 6 With the same waveguide length, the gain of an optical amplifier increases with increasing pump power and gradually saturates. For a fixed pump power, the gain of the optical amplifier increases rapidly with waveguide length in the initial stage. After reaching the optimal waveguide length, the gain reaches its maximum and then begins to decrease. This is because when the waveguide length is short, the pump light is not completely absorbed, and the gain does not reach its maximum value. As the waveguide length increases, the gain gradually increases. At a certain length, the pump light energy is below the pump threshold, and population inversion cannot occur. If the waveguide length increases further, the gain will begin to decrease due to the inherent losses of the waveguide itself. Therefore, the waveguide length corresponding to the maximum gain is the optimal waveguide length, which can be used as the length of the ridge gain layer. Similarly, the waveguide width corresponding to the maximum gain can be determined using the same method as the optimal waveguide width. Combining the optimal waveguide length and optimal waveguide width, the optimal value of the cross-sectional dimensions of the ridge gain layer can be obtained.

[0068] The amplification module provided in this embodiment utilizes the high overlap factor of erbium ions in the ridge gain layer between the pump light of TE1 mode and the signal light of TE0 mode to improve the intermodal gain effect.

[0069] The embodiments disclosed herein provide efficient coupling between pump light and signal light through a multiplexing module and achieve high-gain optical amplification using an amplification module.

[0070] The optical amplifier provided in this disclosure has a simple structure and can achieve high gain while maintaining miniaturization.

[0071] The optical amplifier provided in this disclosure is suitable for pump light of different wavelengths and different rare earth ion doping, and can be widely used in different integrated photonic platforms such as silicon, silicon nitride and lithium niobate, and applied to signal amplification in different communication bands, thus having a certain degree of flexibility.

[0072] This disclosure also provides a transmission system. The transmission system includes the optical amplifier provided in any embodiment of this disclosure.

[0073] It should be noted that, in the embodiments of this disclosure, the transmission system may employ multiple optical amplifiers for multi-stage amplification.

[0074] In some embodiments, the transmission system further includes an optical input module, an input optical fiber, an output optical fiber, and an optical receiving module. The optical input module includes a signal optical input module and a pump optical input module as described above. The optical input module converts an electrical signal into an optical signal and inputs the signal light into the input optical fiber. An optical amplifier is disposed between the input and output optical fibers. The input optical fiber transmits the signal light output from the optical input module to the optical amplifier. The optical amplifier amplifies the signal light input from the input optical fiber and inputs the amplified signal light into the output optical fiber. The optical receiving module converts the optical signal output from the output optical fiber into an electrical signal. Furthermore, optical isolation modules can be installed at both ends of the optical amplifier. These modules prevent light reflection, ensure stable system operation, and reduce noise. An optical filter module can also be installed after the optical isolation module at the output of the optical amplifier. This optical filter module filters out noise from the optical amplifier, improving the system's signal-to-noise ratio.

[0075] It should be understood that the phrase "an embodiment" or "one embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this disclosure. Therefore, "in one embodiment" or "one embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this disclosure, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this disclosure. The sequence numbers of the above-described embodiments are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0076] The above description is merely a preferred embodiment of this disclosure and does not limit the patent scope of this disclosure. Any equivalent structural transformations made using the contents of this specification and drawings under the inventive concept of this disclosure, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this disclosure.

Claims

1. An optical amplifier, characterized in that, The optical amplifier includes: a coupling input module, a multiplexing module, an amplification module, a demultiplexing module, and a coupling output module; wherein, The coupling input module is used to receive the fundamental mode pump light and the fundamental mode signal light, and output them to the multiplexing module; The multiplexing module is used to perform mode conversion on the fundamental mode pump light to obtain non-fundamental mode pump light, and then couple the non-fundamental mode pump light and the fundamental mode signal light to output to the amplification module; The amplification module is used to amplify the fundamental mode signal light; The demultiplexing module is used to decouple the non-fundamental mode pump light from the amplified fundamental mode signal light and output it to the coupling output module.

2. The optical amplifier according to claim 1, characterized in that, The amplification module is used to amplify the fundamental mode signal light using the non-fundamental mode pump light.

3. The optical amplifier according to claim 1, characterized in that, The multiplexing module includes a first input waveguide, a first coupling waveguide, and a first output waveguide; The first coupled waveguide includes a first waveguide and a second waveguide arranged parallel to each other; the effective refractive index neff1 of the pump light transmitted in the first waveguide and the effective refractive index neff2 of the pump light transmitted in the second waveguide satisfy the phase matching condition: neff1(W i ) = neff2(W j ); where W i W is the width of the first waveguide. j The width of the second waveguide is given.

4. The optical amplifier according to claim 3, characterized in that, The demultiplexing module includes a second input waveguide, a second coupling waveguide, and a second output waveguide; The second coupling waveguide includes a fifth waveguide and a sixth waveguide arranged parallel to each other; the effective refractive index neff3 of the pump light transmitted in the fifth waveguide and the effective refractive index neff4 of the pump light transmitted in the sixth waveguide satisfy the phase matching condition: neff3(W m ) = neff4(W n ); where W m W is the width of the fifth waveguide. n The width of the sixth waveguide.

5. The optical amplifier according to claim 4, characterized in that, The structure of the second coupled waveguide is the same as that of the first coupled waveguide.

6. The optical amplifier according to claim 1, characterized in that, The amplification module includes a substrate, an oxide layer, a ridge gain layer, and a waveguide cladding covering the ridge gain layer; The ridge-shaped gain layer is doped with rare earth ions, and the material of the ridge-shaped gain layer includes silicon nitride or lithium niobate.

7. The optical amplifier according to claim 6, characterized in that, The waveguide size of the amplification module is based on the overlap factor η between the corrected light intensity and erbium ions. total Adjustments are made; where η total =Γ×η p,s , ψ p,s For the intensity distribution of the pump light and the signal light, n i (x,y) represents the doping distribution of erbium ions at energy level i. The normalized transverse intensity distribution of the signal light in TE0 mode. The normalized transverse intensity distribution of the pump light in TE1 mode is given by A, where A is the cross-sectional dimension of the ridge gain layer.

8. The optical amplifier according to claim 7, characterized in that, The waveguide dimensions of the amplification module include the length of the ridge gain layer and the cross-sectional dimensions of the ridge gain layer, wherein the cross-sectional dimensions of the ridge gain layer include the width and height of the ridge gain layer.

9. The optical amplifier according to claim 7, characterized in that, The coupling input module and the coupling output module include one or more of the following: a mode converter, a grating coupler, and an array coupler.

10. A transmission system, characterized in that, The transmission system includes the optical amplifier according to any one of claims 1 to 9.

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