Wavelength division multiplexer and optical module
By integrating the phase shifter on the power divider and delay line of the wavelength division multiplexer and adopting a cascade MZI structure, the problems of uneven passband and small process tolerance of the existing wavelength division multiplexer are solved, and a flatter passband and larger process tolerance are achieved.
Patent Information
- Application Number
- CN202411735670.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-03-11
AI Technical Summary
Existing wavelength division multiplexers have problems of uneven passband and small process tolerance.
A wavelength division multiplexer is designed, adopting a cascaded MZI structure, each MZI includes two power dividers and two waveguides of different lengths, one of which comprises a delay line, and at least one of the power dividers and waveguides is provided with a phase shifter.
By integrating phase shifters on the power splitter and delay lines, phase adjustment is achieved, device process tolerance is increased, device performance is optimized, passband is flatter and inter-channel crosstalk is smaller, and more channel multiplexing and demultiplexing is achieved.
Smart Images
Figure CN119602906A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of optical communication technology, and in particular to a wavelength division multiplexer and an optical module. Background Art
[0002] In recent years, with the rapid development of cloud computing and data centers, optical interconnect has become a research focus due to its incomparable advantages over electrical interconnect in terms of power consumption, speed, bandwidth, etc. As one of the important components for building optical interconnect systems, wavelength division (demultiplexer) has also received widespread attention and provided strong support for data centers, artificial intelligence computing, long-distance communications and other fields.
[0003] There are many schemes for constructing wavelength division (de)multiplexers, but they all have certain limitations. For example, although the wavelength division (de)multiplexer based on the cascaded microring resonant cavity structure has a simple principle, it has the disadvantages of large insertion loss and low channel consistency; although the wavelength division (de)multiplexer based on the arrayed waveguide grating structure can multiplex a larger number of channels with a smaller device size, it is more suitable for systems with smaller channel spacing requirements and uneven passband; although the wavelength division (de)multiplexer based on the conventional waveguide grating structure can achieve passband flat output, it often has a small feature size in design, which requires high process accuracy. Summary of the invention
[0004] In view of this, the embodiments of the present application provide a wavelength division multiplexer and an optical module, which at least partially solve the problems of uneven passband and small process tolerance of the wavelength division multiplexer in the prior art.
[0005] In a first aspect, an embodiment of the present application provides a wavelength division multiplexer, comprising a plurality of cascaded MZ I's, each MZ I comprising two power dividers and two waveguides of different lengths located between the two power dividers, one of the two waveguides of different lengths comprising a delay line, and at least one of the waveguide and the power divider being provided with a phase shifter.
[0006] According to a specific implementation manner of an embodiment of the present application, the power divider is configured as a bidigital structure power divider, and the bidigital structure power divider includes a first input waveguide, a second input waveguide, a first output waveguide, a second output waveguide and a coupling waveguide, and the coupling waveguide includes an input coupling region waveguide, a transition region waveguide and an output coupling region waveguide connected in sequence, the first input waveguide and the second input waveguide are arranged in parallel along the light propagation direction, the first output waveguide and the second output waveguide are arranged in parallel along the light propagation direction, the input coupling region waveguide is located between the first input waveguide and the second input waveguide, the output coupling region waveguide is located between the first output waveguide and the second output waveguide, and at least one of the input coupling region waveguide and the output coupling region waveguide is configured as a tapered waveguide.
[0007] According to a specific implementation manner of the embodiment of the present application, at least one of the input coupling region waveguide and the output coupling region waveguide is configured as a structure in which multiple sections of tapered waveguides with different slopes are connected in sequence.
[0008] According to a specific implementation manner of the embodiment of the present application, at least one of the first input waveguide and the second input waveguide includes an input single-mode waveguide and an input tapered waveguide sequentially connected along the light propagation direction, the input tapered waveguide is coupled with the input coupling region waveguide, and the input tapered waveguide is a second tapered structure; and / or, the first output waveguide and the second output waveguide both include an output tapered waveguide and an output single-mode waveguide sequentially connected along the light propagation direction, the output tapered waveguide is coupled with the output coupling region waveguide, and the output tapered waveguide is a third tapered structure.
[0009] According to a specific implementation manner of the embodiment of the present application, the power divider is configured as an MMI power divider or a bent waveguide power divider.
[0010] According to a specific implementation of the embodiment of the present application, the phase shifter is a thermo-optical phase shifter.
[0011] According to a specific implementation of the embodiment of the present application, the waveguide is configured as a folded waveguide.
[0012] According to a specific implementation of the embodiment of the present application, an air gap is etched on the waveguide.
[0013] According to a specific implementation manner of the embodiment of the present application, the delay line is configured as a wide waveguide or a ridge waveguide.
[0014] In a second aspect, an embodiment of the present application further provides an optical module, comprising a wavelength division multiplexer as described in any embodiment of the first aspect above.
[0015] Beneficial effects:
[0016] The wavelength division multiplexer and optical module in the embodiments of the present application can achieve phase adjustment by integrating phase shifters on the power divider and delay line, thereby increasing the device process tolerance; by cascading more MZ I, the device performance can be further optimized, making the passband flatter, reducing the crosstalk between channels, or realizing more channel multiplexing and demultiplexing. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0018] Figure 1 is a schematic structural diagram of a wavelength division multiplexer according to an embodiment of the present invention;
[0019] Figure 2 A schematic diagram of the structure of an MMI power divider according to an embodiment of the present invention;
[0020] Figure 3 is a schematic structural diagram of a bent waveguide power divider according to an embodiment of the present invention;
[0021] Figure 4 is a schematic structural diagram of a bi-digital structure power divider according to an embodiment of the present invention;
[0022] Figure 5 is a diagram showing simulation results of a wavelength division multiplexer lacking a phase shifter according to an embodiment of the present invention;
[0023] Figure 6 FIG. 1 is a diagram showing simulation results of a wavelength division multiplexer with a phase shifter added according to an embodiment of the present invention. DETAILED DESCRIPTION
[0024] The embodiments of the present application are described in detail below with reference to the accompanying drawings.
[0025] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.
[0026] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.
[0027] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show the components related to the present application rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.
[0028] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.
[0029] An embodiment of the present application provides a wavelength division multiplexer, which is described in detail below with reference to the drawings.
[0030] In a first aspect, the present application provides a wavelength division multiplexer, as shown below: Figures 1 to 6 Describe in detail.
[0031] In one embodiment, referring to Figure 1 The wavelength division multiplexer includes several cascaded MZIs, each of which includes two power dividers and two waveguides of different lengths located between the two power dividers, one of the two waveguides of different lengths includes a delay line, and at least one of the waveguide and the power divider is provided with a phase shifter.
[0032] The working principle of the wavelength division multiplexer of this embodiment is as follows: after the light is injected from the input end, it is divided into two waveguides of different lengths by the first power divider. After the two beams of light have a relative phase delay, they converge at the second power divider and form an interference effect. Similarly, similar interference effects are formed in each level of MZI, and the accumulated interference effect can be flat-topped output at each output end through reasonable parameter design.
[0033] In this embodiment, the phase shifter can be set on the power divider, or on the waveguide, or the phase shifter can be set on both the power divider and the waveguide. The specific number of phase shifters is adaptively adjusted according to the actual application. By integrating the phase shifter on the power divider and the delay line, the phase can be adjusted, thereby increasing the device process tolerance. The wavelength division multiplexer can be set as a multi-stage cascaded MZI. Figure 1 Only two stages are shown as an example, which is not limited to two stages of MZI. By cascading more MZIs, the device performance can be further optimized, making the passband flatter, reducing the crosstalk between channels, or realizing more channel multiplexing and demultiplexing.
[0034] In one embodiment, referring to Figure 4 The power divider is configured as a bidigital structure power divider, the bidigital structure power divider comprises a first input waveguide (port1), a second input waveguide (port2), a first output waveguide (port3), a second output waveguide (port4) and a coupling waveguide, the coupling waveguide comprises an input coupling region waveguide, a transition region waveguide and an output coupling region waveguide connected in sequence, the first input waveguide and the second input waveguide are arranged in parallel along a light propagation direction, the first output waveguide and the second output waveguide are arranged in parallel along a light propagation direction, the input coupling region waveguide is located between the first input waveguide and the second input waveguide, the output coupling region waveguide is located between the first output waveguide and the second output waveguide, and at least one of the input coupling region waveguide and the output coupling region waveguide is configured as a tapered waveguide.
[0035] In this embodiment, by setting a bidigital structure power divider, the output spectrum can be made relatively flat; the output optical power can also be adjusted by adjusting the distance between the input coupling region waveguide and the first input waveguide or the second input waveguide; and / or, the output optical power can be adjusted by adjusting the distance between the output coupling region waveguide and the first output waveguide or the second output waveguide, so that optical power output with any splitting ratio can be achieved; and the structure has low process requirements, reduces dependence on processing accuracy, and significantly improves tolerance to manufacturing tolerances.
[0036] Furthermore, at least one of the input coupling region waveguide and the output coupling region waveguide is configured as a structure in which multiple sections of tapered waveguides with different slopes are connected in sequence.
[0037] Further, at least one of the first input waveguide and the second input waveguide includes an input single-mode waveguide and an input tapered waveguide sequentially connected along the light propagation direction, the input tapered waveguide is coupled with the input coupling region waveguide, and the input tapered waveguide is a second tapered structure; and / or, the first output waveguide and the second output waveguide both include an output tapered waveguide and an output single-mode waveguide sequentially connected along the light propagation direction, the output tapered waveguide is coupled with the output coupling region waveguide, and the output tapered waveguide is a third tapered structure.
[0038] In this embodiment, by providing a structure in which multiple sections of tapered waveguides with different slopes are connected, the size of the device can be reduced, which is beneficial for processing and manufacturing, and the flexibility of application scenarios can be improved.
[0039] In one embodiment, the power divider is configured as an MMI power divider or a curved waveguide power divider. Figure 2 As shown, the structure of the bent waveguide power divider is referenced Figure 3 As shown, by setting it as an MMI power divider or a bent waveguide power divider, the process tolerance of the power divider can be large and the wavelength is insensitive, which is beneficial to device manufacturing and reduces the influence of the manufacturing process on the device performance.
[0040] In one embodiment, the phase shifter is a thermo-optical phase shifter, which is a device that adjusts the phase of an optical signal by changing the temperature of a waveguide material, and is mainly used in the fields of optical communication, optical computing, etc.
[0041] In this embodiment, the performance of the wavelength division multiplexer is optimized by adding a thermo-optical phase shifter, and the optimization principle is as follows:
[0042] Applying voltage to the thermo-optical phase shifter can change the optical phase difference Δφ, thus causing the effective length ΔL of the delay line to change. Figure 1 As shown, ΔL1-ΔL4 are freely adjustable, so that the performance of the wavelength division multiplexer can be optimized. In addition, thermo-optical phase shifters can also be integrated on the first to seventh power dividers to strictly control each splitting ratio, which will further optimize the performance of the wavelength division multiplexer. For the impact of using thermo-optical phase shifters on the performance of the wavelength division multiplexer, refer to Figure 5 and Figure 6 The simulation results show that adding a thermo-optical phase shifter can achieve phase adjustment, thereby increasing the device process tolerance.
[0043] The relationship between the optical phase difference and the effective length of the delay line is shown in the following formula:
[0044]
[0045] Where Δφ is the optical phase difference; ΔL is the effective length of the delay line; λ is the operating wavelength; neff is the effective refractive index of the waveguide.
[0046] by Figure 1 For example, in theory, ΔL1 = ΔL, ΔL2 = 2ΔL, ΔL3 = ΔL / 2, and ΔL4 = ΔL / 2. However, in actual simulations, these may deviate, such as ΔL1 = ΔL+0.5um is better. In order to reduce the device size as much as possible, the delay line length difference should be as small as possible while meeting the requirements.
[0047] In specific implementation, the thermo-optic phase shifter can be prepared entirely or only on one arm of the MZ I. Since adding the thermo-optic phase shifter will increase power consumption, the power consumption can be reduced by folding the waveguide, etching an air gap, etc.
[0048] In one embodiment, the waveguide is arranged as a folded waveguide.
[0049] In one embodiment, an air gap is etched into the waveguide.
[0050] In one embodiment, the delay line is configured as a wide waveguide or a ridge waveguide. In this embodiment, the delay lines (ΔL1, ΔL2, ΔL3, ΔL4) can be designed with a wide waveguide, a ridge waveguide or other structures to increase the device process tolerance.
[0051] In a second aspect, an embodiment of the present application further provides an optical module, comprising a wavelength division multiplexer as described in any embodiment of the first aspect above.
[0052] It should be noted that the structure of the optical division multiplexer of the present application can also be used as a wavelength division multiplexer.
[0053] In the embodiments provided by the present invention, the power divider can adopt a structural design with large process tolerance and insensitivity to wavelength (such as an MMI structure, a curved waveguide or a bidigital structure power divider); by setting the delay line as a wide waveguide, a ridge waveguide or other structural designs, the device process tolerance is increased; by integrating a thermo-optical phase shifter on the power divider and the delay line, the phase is adjustable, thereby increasing the device process tolerance, and the power consumption can be reduced by waveguide folding, etching air gaps, etc.; cascading more MZIs further optimizes the device performance, making the passband flatter and the crosstalk between channels smaller; and more channel multiplexing and demultiplexing can be achieved.
[0054] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.
Claims
1. A wavelength division multiplexer, characterized in that: The invention comprises several cascaded MZIs, each of which comprises two power dividers and two waveguides of different lengths located between the two power dividers, one of the two waveguides of different lengths comprises a delay line, and at least one of the waveguide and the power divider is provided with a phase shifter.
2. The wavelength division multiplexer according to claim 1, characterized in that: The power divider is configured as a bidigital structure power divider, comprising a first input waveguide, a second input waveguide, a first output waveguide, a second output waveguide and a coupling waveguide, wherein the coupling waveguide comprises an input coupling region waveguide, a transition region waveguide and an output coupling region waveguide connected in sequence, wherein the first input waveguide and the second input waveguide are arranged in parallel along a light propagation direction, wherein the first output waveguide and the second output waveguide are arranged in parallel along a light propagation direction, wherein the input coupling region waveguide is located between the first input waveguide and the second input waveguide, wherein the output coupling region waveguide is located between the first output waveguide and the second output waveguide, and wherein at least one of the input coupling region waveguide and the output coupling region waveguide is configured as a tapered waveguide.
3. The wavelength division multiplexer according to claim 2, characterized in that: At least one of the input coupling region waveguide and the output coupling region waveguide is configured as a structure in which multiple sections of tapered waveguides with different slopes are connected in sequence.
4. The wavelength division multiplexer according to claim 2, characterized in that: At least one of the first input waveguide and the second input waveguide includes an input single-mode waveguide and an input tapered waveguide sequentially connected along the light propagation direction, the input tapered waveguide is coupled with the input coupling region waveguide, and the input tapered waveguide is a second tapered structure; and / or, the first output waveguide and the second output waveguide both include an output tapered waveguide and an output single-mode waveguide sequentially connected along the light propagation direction, the output tapered waveguide is coupled with the output coupling region waveguide, and the output tapered waveguide is a third tapered structure.
5. The wavelength division multiplexer according to claim 1, characterized in that: The power divider is configured as an MMI power divider or a bent waveguide power divider.
6. The wavelength division multiplexer according to claim 1, characterized in that: The phase shifter is a thermo-optical phase shifter.
7. The wavelength division multiplexer according to claim 1, characterized in that: The waveguide is configured as a folded waveguide.
8. The wavelength division multiplexer according to claim 1, characterized in that: An air gap is etched on the waveguide.
9. The wavelength division multiplexer according to claim 1, characterized in that: The delay line is configured as a wide waveguide or a ridge waveguide.
10. An optical module, characterized in that: Comprising the wavelength division multiplexer as described in any one of claims 1-9.