Reflection-type MEMS attenuator with adjustable slope

Abstract

The invention discloses a reflection-type MEMS attenuator with an adjustable slope, and relates to the technical field of photoelectronics, and an optical path of the reflection-type MEMS attenuator with the adjustable slope sequentially comprises an emergent optical fiber, a plano-convex lens, a diffraction grating, a wedge angle sheet, a reflector and a receiving optical fiber, the relative positions of the emergent optical fiber and the receiving optical fiber are fixed; the inclined surface of the wedge angle sheet faces the diffraction grating; the intersection line of the inclined plane and the vertical plane of the wedge-angle sheet is positioned at the bottom of the wedge-angle sheet; in a light path of the reflective MEMS attenuator with the adjustable slope, a light beam emitted by an emergent optical fiber is collimated by a plano-convex lens and then hit on a diffraction grating, the light beam sequentially passes through the diffraction grating and a wedge angle sheet to generate spatial separation and reaches a reflective mirror controlled by the MEMS, and the spatial positions of the light paths reflected by the reflective mirror are different. And the proportions of light components with different wavelengths received by the receiving optical fiber are different. According to the invention, dynamic regulation and control of the attenuation slope of the reflective MEMS attenuator are realized.

Description

Technical Field

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

[0002] In optical communication systems and photonic integrated devices, the Micro Electro Mechanical System (MEMS) rotating mirror type variable optical attenuator (VOA) achieves dynamic and continuous adjustment of optical power by driving the micromirror to rotate and change the coupling efficiency of the reflected light path. With high precision, millisecond response speed and compact packaging, this type of device has become a core component for optical power equalization of dense wavelength division multiplexing (DWDM) systems, gain flattening of erbium doped fiber amplifiers (EDFA) and optimization of the signal-to-noise ratio at the receiving end. Its core advantage is that a wide range of insertion loss adjustment can be achieved through the control of a single actuator, but the attenuation characteristics in the traditional MEMS attenuator design are independent of the wavelength, that is, the wavelength-related loss approaches zero.

[0003] However, as optical networks evolve towards software-defined and functionally reconfigurable, the need for dynamic regulation of wavelength-selective attenuation slopes has become increasingly prominent. For example, in multi-stage cascaded optical amplification systems, the power gradient of each channel needs to be adjusted in real time according to the link length to compensate for the slope accumulation caused by the nonlinear effect of the optical fiber; in fiber Bragg grating sensor networks, programmable attenuation slopes are required to suppress crosstalk noise in specific wavelength ranges. It can be seen that dynamic adjustment of attenuation slopes is crucial to 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, thereby realizing dynamic regulation of the attenuation slope of the reflective MEMS attenuator.

[0005] To achieve the above objectives, this application provides the following solutions.

[0006] The present application provides a slope-adjustable reflective MEMS attenuator, which comprises: an optical fiber array, a plano-convex lens, a diffraction grating, a wedge-shaped 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 plate faces the diffraction grating; the intersection line of the inclined surface of the wedge-shaped plate and the vertical surface 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 of the wedge-shaped plate and the vertical surface; in the optical path of the slope-adjustable reflective MEMS attenuator, the light beam emitted by the emitting 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 path reflected by the reflector are different, and the proportions of light components of different wavelengths received by the receiving optical fiber are different.

[0007] Optionally, the inclination angle of the wedge-shaped piece 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 piece.

[0008] Optionally, 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.

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

[0010] Optionally, the material used for the wedge-angle piece and the plano-convex lens is N-SF11.

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

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

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

[0014] According to the specific embodiments provided in this application, this application discloses the following technical effects.

[0015] In this application, the light beam emitted from the output optical fiber is collimated by a plano-convex lens and then hits the diffraction grating. The light beam passes through the diffraction grating and the wedge-shaped piece in sequence, and then is spatially separated and reaches the reflector controlled by the MEMS. The spatial positions of the light paths reflected by the reflector are different, and the proportions of light components of different wavelengths received by the receiving optical fiber are also different. The focus of this application is to set a wedge-shaped piece of corresponding angle behind the diffraction grating, the purpose of which is to produce role dispersion in the opposite direction to the diffraction grating, so as to perform partial dispersion compensation, so that the light beam can ensure a large wavelength-dependent loss (WavelengthDependent Loss, WDL) at the maximum insertion loss point, while also ensuring that the WDL is as small as possible at the minimum insertion loss point. It is for the above reasons that 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 the present application or related technologies, 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 labor.

[0017] Figure 1 A side view of the optical path of a reflective MEMS attenuator with adjustable slope provided in an embodiment of the present application.

[0018] Figure 2 A top view of the optical path of a reflective MEMS attenuator with adjustable slope provided in an embodiment of the present application.

[0019] Figure 3 This is an attenuation curve corresponding to the reflective MEMS attenuator with adjustable slope provided in an embodiment of the present application.

[0020] Figure 4 This is an attenuation curve diagram corresponding to the traditional MEMS attenuator provided in an embodiment of the present application.

[0021] Explanation of symbols: optical fiber array-1, output optical fiber-11, receiving optical fiber-12, plano-convex lens-2, diffraction grating-3, wedge-4, reflector-5. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] The purpose of the present application is to provide a reflective MEMS attenuator with adjustable slope, thereby realizing dynamic regulation of the attenuation slope of the reflective MEMS attenuator.

[0024] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0025] like Figure 1 and Figure 2 As shown, this embodiment provides a reflective MEMS attenuator with adjustable slope, which includes: an optical fiber array 1 (including an output optical fiber 11 and a receiving optical fiber 12), a plano-convex lens 2, a diffraction grating 3, a wedge 4 and a reflector 5 (which is controlled by MEMS to rotate around a fixed axis).

[0026] Among them, the relative positions of the emitting optical fiber 11 and the receiving optical fiber 12 are fixed; the inclined surface of the wedge 4 faces the diffraction grating 3, and the intersection line of the inclined surface of the wedge 4 and the vertical plane is located at the bottom of the wedge 4; the inclination angle range of the wedge 4 is [10°, 45°], the inclination angle of the wedge 4 is the angle between the inclined surface of the wedge 4 and the vertical plane, and the inclination angle of the wedge 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 4; the thickness range of the wedge 4 is [0.1mm, 1mm], and the thickness of the wedge 4 is the distance between the midpoint of the inclined surface of the wedge 4 and the midpoint of the vertical plane.

[0027] As a preferred implementation manner, in this embodiment, the Abbe coefficients of the wedge plate 4 and the plano-convex lens 2 are less than 30, the material used for the wedge plate 4 and the plano-convex lens 2 is N-SF11, and the line 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 slope-adjustable reflective MEMS attenuator comprises: an output optical fiber 11, a plano-convex lens 2, a diffraction grating 3, a wedge-shaped plate 4, a reflector 5, and a receiving optical fiber 6 in sequence. In the optical path of the slope-adjustable reflective MEMS attenuator, the light beam emitted by the output optical fiber 11 is collimated by the plano-convex lens 2 and then hits the diffraction grating 3. The light beam is spatially separated after passing through the diffraction grating 3 and the wedge-shaped plate 4 in sequence and reaches the reflector 5 controlled by the MEMS. The spatial positions of the optical paths reflected by the reflector 5 are different, and the proportions of light components of different wavelengths received by the receiving optical fiber 12 are also different. By matching and designing the period of the diffraction grating 3 and the inclination parameters of the wedge-shaped plate 4, 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 between the reflector angle, IL, and d(IL) / dλ, the slope at any insertion loss point can be dynamically matched to obtain the corresponding WDL value.

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

[0030] First, the line number of the diffraction grating 3 is set to 20 gr / mm, the thickness of the wedge 4 is set to 0.3 mm, the inclination angle of the wedge 4 is set to 11°, and the optical fiber array 1 is kept fixed (ie, the relative position of the emitting optical fiber 11 and the receiving optical fiber 12 is fixed).

[0031] In the actual working process, the light beam is emitted from the output optical 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 produce dispersion (with strong dispersion ability), and separate the incident light beam in space according to wavelength to form a wavelength-space mapping relationship. Specifically, the dispersion ability of the diffraction grating 3 is given by the grating equation Determine, its role dispersion rate , where d is the grating constant, m is the diffraction order, For the incident role, The diffraction order is m The diffraction angle.

[0032] The light beam passing through the diffraction grating 3 further enters the wedge 4, which can also disperse the light beam and separate the incident light beam in space according to wavelength. However, the dispersion ability of the wedge 4 is relatively weak. Specifically, the dispersion ability of the wedge 4 on the light beam mainly comes from the refractive index of the material. n ( ), whose role dispersion is , where L is the length of the bottom side of the wedge-shaped piece 4, A is the beam cross-sectional area, and the dispersion capability of the diffraction grating 3 is usually 1-2 orders of magnitude higher than that of the wedge plate 4. Figure 2 Side view of the middle wedge 4. In this embodiment, the inclination of the wedge 4 is set from the upper left to the lower right. The purpose is to produce a role dispersion opposite to the diffraction grating 3, so as to perform partial dispersion compensation, so that the light beam can have a larger WDL at the maximum insertion loss point while ensuring a minimum WDL at the minimum insertion loss point.

[0033] The light beam passing through the wedge 4 reaches the reflector 5 controlled by the MEMS. Since the incident angles of each wavelength component are different, the spatial positions of the light paths reflected by the reflector 5 are also different, so that the proportions of light components of different wavelengths that can be received by the receiving optical fiber 12 are also different, and the proportion of each wavelength of light received presents a nonlinear change. Therefore, when the insertion loss increases (that is, when the reflector 5 rotates past the optimal coupling angle), the short-wavelength light is not received by the receiving optical fiber 12 earlier due to the dispersion angle offset, resulting in a steep increase in the slope of the short-wavelength band of the attenuation curve.

[0034] like Figure 3 As shown in the figure, when the initial angle of the reflector 5 is controlled by MEMS at 10.23°, the optimal insertion loss of the 1575nm wavelength can reach -0.04dB, and the slope of the WDL curve tends to 0; when the inclination angle of the reflector 5 is switched to 10.259° by MEMS, the attenuation of the light at the 1575nm wavelength is -0.45dB, and the attenuation of the light at the 1520nm wavelength can reach -3.47dB. Figure 4 The attenuation effect achieved by the traditional MEMS VOA structure, the present application can realize the dynamic regulation of the attenuation slope of the reflective MEMS attenuator.

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

[0036] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this 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.

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 MEMS is used to control the reflection mirror to rotate around a fixed axis.

8. 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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