A reflective MEMS attenuator with adjustable slope

Abstract

The present application discloses a reflective MEMS attenuator with adjustable slope, which relates to the field of optoelectronic technology. The optical path of the reflective MEMS attenuator with adjustable slope sequentially includes: an output optical fiber, a plano-convex lens, a diffraction grating, a wedge-shaped plate, a reflector, and a receiving optical fiber; the relative positions of the output optical fiber and the receiving optical fiber are fixed; the inclined surface of the wedge-shaped plate faces the diffraction grating; the intersection line of the inclined surface and the vertical surface of the wedge-shaped plate is located at the bottom of the wedge-shaped plate; in the optical path of the reflective MEMS attenuator with adjustable slope, the light beam emitted by the output optical fiber is collimated by the plano-convex lens and then hits the diffraction grating. After passing through the diffraction grating and the wedge-shaped plate in sequence, the light beam is spatially separated and reaches the reflector controlled by MEMS. The spatial positions of the optical paths reflected by the reflector are different, and the proportions of different wavelength light components received by the receiving optical fiber are different. The present application realizes the dynamic regulation of the attenuation slope of the reflective MEMS attenuator.

Description

Technical Field

[0001] The present application relates to the field of optoelectronic technologies, and particularly to a reflective MEMS attenuator with adjustable slope. Background Art

[0002] In optical communication systems and photonic integrated devices, a micro-electro-mechanical system (MEMS) mirror-based variable optical attenuator (VOA) adjusts the coupling efficiency of the reflection optical path by driving the rotation of a micromirror, thereby achieving dynamic and continuous adjustment of the optical power. With its high precision, millisecond-level response speed, and compact packaging, such devices have become core components for optical power equalization in dense wavelength division multiplexing (DWDM) systems, gain flattening of erbium-doped fiber amplifiers (EDFAs), and optimization of the signal-to-noise ratio at the receiving end. Their core advantage lies in the ability to achieve wide-range adjustment of insertion loss through the control of a single actuator. However, in the design of traditional MEMS attenuators, the attenuation characteristics are independent of wavelength, i.e., the wavelength-dependent loss approaches zero.

[0003] However, with the evolution of optical networks towards software-defined and function-reconfigurable directions, the demand for dynamic regulation of the wavelength-selective attenuation slope has become increasingly prominent. For example, in a multi-stage cascaded optical amplification system, it is necessary to adjust the power gradient of each channel in real time according to the link length to compensate for the slope accumulation caused by fiber nonlinear effects; in a fiber Bragg grating sensing network, it is necessary to suppress crosstalk noise in a specific wavelength range through a programmable attenuation slope. Therefore, the dynamic adjustment of the attenuation slope is crucial for the development of MEMS attenuators. Summary of the Invention

[0004] The purpose of the present application is to provide a reflective MEMS attenuator with adjustable slope, which realizes the dynamic regulation of the attenuation slope of the reflective MEMS attenuator.

[0005] To achieve the above purpose, the present application provides the following solutions.

[0006] The present application provides a reflective MEMS attenuator with adjustable slope. The reflective MEMS attenuator with adjustable slope includes: an optical fiber array, a plano-convex lens, a diffraction grating, a wedge-shaped plate, and a reflector; the optical fiber array includes an outgoing optical fiber and a receiving optical fiber; the relative positions of the outgoing optical fiber and the receiving optical fiber are fixed; the inclined surface of the wedge-shaped plate faces the diffraction grating; the intersection line of the inclined surface and the vertical plane of the wedge-shaped plate is located at the bottom of the wedge-shaped plate; the inclination angle range of the wedge-shaped plate is [10°, 45°]; the inclination angle of the wedge-shaped plate is the angle between the inclined surface and the vertical plane of the wedge-shaped plate; in the optical path of the reflective MEMS attenuator with adjustable slope, the light beam emitted from the outgoing optical fiber is collimated by the plano-convex lens and then hits the diffraction grating, the light beam is spatially separated after passing through the diffraction grating and the wedge-shaped plate in sequence and reaches the reflector controlled by MEMS, the spatial positions of the optical paths reflected by the reflector are different, and the proportions of different wavelength light components received by the receiving optical fiber are different.

[0007] Optionally, the inclination angle of the wedge-shaped plate is determined by the number of lines of the diffraction grating; the number of lines of the diffraction grating is proportional to the inclination angle of the wedge-shaped plate.

[0008] Optionally, the thickness range of the wedge-shaped plate is [0.1 mm, 1 mm]; the thickness of the wedge-shaped plate is the distance between the midpoints of the inclined surface and the vertical plane of the wedge-shaped plate.

[0009] Optionally, the Abbe numbers of the wedge-shaped plate and the plano-convex lens are less than 30.

[0010] Optionally, the materials used for the wedge-shaped plate and the plano-convex lens are N-SF11.

[0011] Optionally, the grating line density of the diffraction grating is less than 100 gr / mm.

[0012] Optionally, the MEMS is used to control the rotation of the reflector around a fixed axis.

[0013] Optionally, the operating wavelength range of the reflective MEMS attenuator with adjustable slope is [1520 nm, 1575 nm].

[0014] According to the specific embodiments provided by the present application, the following technical effects are disclosed in the present application.

[0015] In this application, the light beam emitted from the output optical fiber is collimated by a plano-convex lens and then hits a diffraction grating. After passing through the diffraction grating and the wedge prism in sequence, the light beam is spatially separated and reaches a mirror controlled by MEMS. The spatial positions of the optical paths reflected by the mirror are different, and the proportions of the light components with different wavelengths received by the receiving optical fiber are also different. The key point of this application is to set a wedge prism with a corresponding angle behind the diffraction grating, aiming to generate angular dispersion opposite to that of the diffraction grating, so as to perform partial dispersion compensation, so that while ensuring a large insertion loss point, the light beam has a large wavelength-dependent loss (WDL), and at the same time, it can also ensure a small WDL at the minimum insertion loss point. Based on the above reasons, this application realizes the dynamic regulation of the attenuation slope of the reflective MEMS attenuator. Brief Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a side view of the optical path of the reflective MEMS attenuator with adjustable slope provided by the embodiment of this application.

[0018] Figure 2 It is a top view of the optical path of the reflective MEMS attenuator with adjustable slope provided by the embodiment of this application.

[0019] Figure 3 It is the attenuation curve diagram corresponding to the reflective MEMS attenuator with adjustable slope provided by the embodiment of this application.

[0020] Figure 4 It is the attenuation curve diagram corresponding to the traditional MEMS attenuator provided by the embodiment of this application.

[0021] Symbol Explanation: Fiber Array - 1, Output Optical Fiber - 11, Receiving Optical Fiber - 12, Plano-Convex Lens - 2, Diffraction Grating - 3, Wedge Prism - 4, Mirror - 5. Detailed Description of the Embodiment

[0022] The following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, rather than all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0023] The purpose of this application is to provide a reflective MEMS attenuator with adjustable slope, which realizes the dynamic regulation of the attenuation slope of the reflective MEMS attenuator.

[0024] To make the above objects, features, and advantages of this application more obvious and understandable, the following further details this application in conjunction with the accompanying drawings and specific embodiments.

[0025] As shown in Figure 1 and Figure 2 This embodiment provides a reflective MEMS attenuator with adjustable slope. The reflective MEMS attenuator with adjustable slope includes: an optical fiber array 1 (including an outgoing optical fiber 11 and a receiving optical fiber 12), a plano-convex lens 2, a diffraction grating 3, a wedge angle plate 4, and a mirror 5 (controlled by MEMS to rotate around a fixed axis).

[0026] Among them, the relative positions of the outgoing optical fiber 11 and the receiving optical fiber 12 are fixed; the inclined surface of the wedge angle plate 4 faces the diffraction grating 3, and the intersection line of the inclined surface and the vertical surface of the wedge angle plate 4 is located at the bottom of the wedge angle plate 4; the inclination angle range of the wedge angle plate 4 is [10°, 45°], and the inclination angle of the wedge angle plate 4 is the angle between the inclined surface and the vertical surface of the wedge angle plate 4. The inclination angle of the wedge angle plate 4 is determined by the number of lines of the diffraction grating 3. The larger the number of lines of the diffraction grating 3, the larger the inclination angle of the wedge angle plate 4; the thickness range of the wedge angle plate 4 is [0.1 mm, 1 mm], and the thickness of the wedge angle plate 4 is the distance between the midpoints of the inclined surface and the vertical surface of the wedge angle plate 4.

[0027] As a preferred embodiment, the Abbe numbers of the wedge angle plate 4 and the plano-convex lens 2 in this embodiment are less than 30. The materials used for the wedge angle plate 4 and the plano-convex lens 2 are N-SF11, and the grating density of the diffraction grating 3 is less than 100 gr / mm (number of grooves per millimeter).

[0028] Furthermore, the optical path of the above-mentioned reflective MEMS attenuator with adjustable slope sequentially includes: an outgoing optical fiber 11, a plano-convex lens 2, a diffraction grating 3, a wedge angle plate 4, a mirror 5, and a receiving optical fiber 12. In the optical path of the reflective MEMS attenuator with adjustable slope, the light beam emitted from the outgoing optical fiber 11 is collimated by the plano-convex lens 2 and then hits the diffraction grating 3. After passing through the diffraction grating 3 and the wedge angle plate 4 in sequence, the light beam is spatially separated and reaches the mirror 5 controlled by MEMS. The spatial positions of the optical paths reflected by the mirror 5 are different, and the proportions of different wavelength light components received by the receiving optical fiber 12 are also different. By matching and designing the period of the diffraction grating 3 and the inclination angle parameters of the wedge angle plate 4, it is ensured that there is a quadratic function relationship between the insertion loss value (IL) and the wavelength attenuation, so that there is a corresponding relationship between IL and WDL. By pre-calibrating the relationship among the mirror angle - IL - d(IL) / dλ, the dynamic matching of the slope at any insertion loss point can be realized, and the corresponding WDL value can be obtained.

[0029] Furthermore, in this embodiment, the operating wavelength range of the slope-tunable reflective MEMS attenuator is [1520 nm, 1575 nm]. Next, based on the above slope-tunable reflective MEMS attenuator, the optimal insertion loss condition for light with a wavelength of 1575 nm is determined.

[0030] First, set the number of lines of the diffraction grating 3 to 20 gr / mm, the thickness of the wedge-shaped plate 4 to 0.3 mm, and the inclination angle of the wedge-shaped plate 4 to 11°, and keep the fiber array 1 fixed (i.e., the relative positions of the outgoing fiber 11 and the receiving fiber 12 are fixed).

[0031] During the actual working process, the light beam is emitted from the outgoing fiber 11, collimated by the plano-convex lens 2 and then hits the diffraction grating 3. Based on the diffraction principle, the diffraction grating 3 can generate dispersion (with strong dispersion ability), and separate the incident light beam in space according to the wavelength to form a wavelength-space mapping relationship. Specifically, the dispersion ability of the diffraction grating 3 is determined by the grating equation and its angular dispersion rate is , where d is the grating constant, m is the diffraction order, is the incident angle, is the diffraction angle when the diffraction order is m .

[0032] The light beam passing through the diffraction grating 3 further enters the wedge-shaped plate 4. The wedge-shaped plate 4 can also generate dispersion for the light beam, separating the incident light beam in space according to the wavelength, but the dispersion ability of the wedge-shaped plate 4 is relatively weak. Specifically, the dispersion ability of the wedge-shaped plate 4 for the light beam mainly comes from the refractive index n of the material ( ), and its angular dispersion rate is , where L is the bottom edge length of the wedge-shaped plate 4, A is the cross-sectional area of the light beam. The dispersion ability of the diffraction grating 3 is usually 1-2 orders of magnitude higher than that of the wedge-shaped plate 4. Referring to the side view of the wedge-shaped plate 4 in Figure 2 , in this embodiment, the inclination of the wedge-shaped plate 4 is set from the upper left to the lower right. The purpose is to generate angular dispersion opposite to that of the diffraction grating 3, so as to perform partial dispersion compensation, so that the light beam can ensure a large WDL at the large insertion loss point and also ensure a small WDL at the minimum insertion loss point.

[0033] The light beam passing through the wedge angle piece 4 reaches the MEMS-controlled mirror 5. Due to the different incident angles of each wavelength component, the spatial positions of the optical paths reflected by the mirror 5 are also different, so that the proportions of different wavelength light components that can be received by the receiving optical fiber 12 are also different, and the proportions of each wavelength of light received show non-linear changes. Therefore, when the insertion loss increases (i.e., when the mirror 5 rotates through the optimal coupling angle), the short-wavelength light is not received by the receiving optical fiber 12 earlier due to the dispersion angle shift, resulting in a sharp increase in the slope of the short-wave band of the attenuation curve.

[0034] As Figure 3 shown, when the initial angle of the MEMS-controlled mirror 5 is 10.23°, the optimal insertion loss at a wavelength of 1575 nm can reach -0.04 dB while the slope of the WDL curve tends to 0; when the inclination angle of the MEMS-controlled mirror 5 is switched to 10.259°, the optical attenuation at a wavelength of 1575 nm is -0.45 dB, and at this time, the optical attenuation at a wavelength of 1520 nm can reach -3.47 dB. Comparing Figure 4 with the attenuation effect achieved by the traditional MEMS VOA structure, the present application can achieve dynamic regulation of the attenuation slope of the reflective MEMS attenuator.

[0035] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0036] Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, based on the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A reflective MEMS attenuator with adjustable slope, characterized in that: The slope-adjustable reflective MEMS attenuator comprises: an optical fiber array, a plano-convex lens, a diffraction grating, a wedge-angle plate and a reflector; the optical fiber array comprises an emitting optical fiber and a receiving optical fiber; The relative positions of the emitting optical fiber and the receiving optical fiber are fixed; the inclined surface of the wedge-shaped piece faces the diffraction grating; the intersection line of the inclined surface of the wedge-shaped piece and the vertical surface is located at the bottom of the wedge-shaped piece; the inclination angle range of the wedge-shaped piece is [10°, 45°]; the inclination angle of the wedge-shaped piece is the angle between the inclined surface of the wedge-shaped piece and the vertical surface; In the optical path of the slope-adjustable reflective MEMS attenuator, the light beam emitted by the output optical fiber is collimated by the plano-convex lens and then hits the diffraction grating. The light beam is spatially separated after passing through the diffraction grating and the wedge-shaped piece in sequence and reaches the reflector controlled by the MEMS. The spatial positions of the light path reflected by the reflector are different, and the proportions of light components of different wavelengths received by the receiving optical fiber are different. The MEMS is used to control the reflection mirror to rotate around a fixed axis; By matching the period of the diffraction grating and the inclination parameters of the wedge, a quadratic function relationship is created between the insertion loss value and the wavelength attenuation, and a corresponding relationship is created between the insertion loss value IL and the wavelength-dependent loss WDL. By pre-calibrating the relationship between the reflector angle, IL, and d(IL) / dλ, dynamic matching of the slope at any insertion loss point is achieved to obtain the corresponding WDL value.

2. The reflective MEMS attenuator with adjustable slope according to claim 1, characterized in that: The inclination angle of the wedge-shaped plate is determined by the number of lines of the diffraction grating; the number of lines of the diffraction grating is proportional to the inclination angle of the wedge-shaped plate.

3. The reflective MEMS attenuator with adjustable slope according to claim 1, characterized in that: The thickness range of the wedge-shaped piece is [0.1 mm, 1 mm]; the thickness of the wedge-shaped piece is the distance between the midpoint of the inclined plane and the midpoint of the vertical plane of the wedge-shaped piece.

4. The reflective MEMS attenuator with adjustable slope according to claim 1, characterized in that: The Abbe coefficients of the wedge-shaped plate and the plano-convex lens are less than 30.

5. The reflective MEMS attenuator with adjustable slope according to claim 1, characterized in that: The material used for the wedge-angle piece and the plano-convex lens is N-SF11.

6. The reflective MEMS attenuator with adjustable slope according to claim 1, characterized in that: The diffraction grating has a line density of less than 100 gr / mm.

7. The reflective MEMS attenuator with adjustable slope according to claim 1, characterized in that: The operating wavelength range of the slope-adjustable reflective MEMS attenuator is [1520 nm, 1575 nm].

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