CN119805666B

CN119805666B - A reflective MEMS attenuator with adjustable slope

Info

Publication number: CN119805666B
Application number: CN202510293186.2A
Authority: CN
Inventors: 王中生; 李佩慧
Original assignee: Guangdong Sanshiyuan Technology Co ltd
Current assignee: Guangdong Sanshiyuan Technology Co ltd
Priority date: 2025-03-13
Filing date: 2025-03-13
Publication date: 2025-06-17
Anticipated expiration: 2045-03-13
Also published as: CN119805666A

Abstract

The application discloses a reflection type MEMS attenuator with adjustable slope, which relates to the technical field of photoelectrons, wherein the optical path composition of the reflection type MEMS attenuator with adjustable slope sequentially comprises an emergent optical fiber, a plano-convex lens, a diffraction grating, a wedge angle piece, a reflecting mirror and a receiving optical fiber; the optical path of the reflection type MEMS attenuator with adjustable slope is characterized in that the relative positions of the emergent optical fiber and the receiving optical fiber are fixed, the inclined plane of the wedge angle piece faces the diffraction grating, the intersection line of the inclined plane and the vertical plane of the wedge angle piece is positioned at the bottom of the wedge angle piece, the light beam emitted by the emergent optical fiber is collimated by the plano-convex lens and then is beaten on the diffraction grating, the light beam sequentially passes through the diffraction grating and the wedge angle piece to generate space separation and reaches the reflector controlled by the MEMS, the space positions of the light paths reflected by the reflector are different, and the proportion of light components with different wavelengths received by the receiving optical fiber is different. The application realizes the dynamic regulation and control of the attenuation slope of the reflective MEMS attenuator.

Description

Slope-adjustable reflective MEMS attenuator

Technical Field

The application relates to the technical field of photoelectrons, in particular to a slope-adjustable reflective MEMS attenuator.

Background

In an optical communication system and a photon integrated device, a Micro Electro MECHANICAL SYSTEM, MEMS (Micro Electro MECHANICAL SYSTEM, MEMS) turning mirror type variable optical attenuator (Variable Optical Attenuator, VOA) changes coupling efficiency of a reflecting light path by driving a Micro mirror to rotate, so that dynamic continuous adjustment of optical power is realized. Such devices have become core elements for optical power equalization of dense wavelength division multiplexing (DENSE WAVELENGTH Division Multiplexing, DWDM) systems, gain flattening of erbium-doped fiber amplifiers (Erbium Doped Fiber Amplifier, EDFA) and signal-to-noise ratio optimization at the receiving end by virtue of high precision, millisecond response speed and compact packaging. The core advantage is that a wide range of insertion loss adjustment can be achieved by single actuator control, but the attenuation characteristics in conventional MEMS attenuator designs are independent of wavelength, i.e. the wavelength dependent loss approaches zero.

However, as the optical network evolves towards software definition and functional reconfiguration, the requirement for dynamic regulation and control of the wavelength selective attenuation slope is increasingly highlighted, for example, in a multistage cascade optical amplification system, the power gradient of each channel needs to be adjusted in real time according to the link length so as to compensate slope accumulation caused by the nonlinear effect of the optical fiber, and in the optical fiber bragg grating sensing network, crosstalk noise in a specific wavelength interval needs to be suppressed through a programmable attenuation slope. It follows that dynamic adjustment of the attenuation slope is critical to the development of MEMS attenuators.

Disclosure of Invention

The application aims to provide a reflection type MEMS attenuator with an adjustable slope, which realizes the dynamic regulation of the attenuation slope of the reflection type MEMS attenuator.

In order to achieve the above object, the present application provides the following.

The application provides a slope-adjustable reflection-type MEMS attenuator which comprises an optical fiber array, a plano-convex lens, a diffraction grating, a wedge angle piece and a reflecting mirror, wherein the optical fiber array comprises an emergent optical fiber 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 piece faces the diffraction grating, the intersection line of the inclined surface of the wedge angle piece and a vertical plane is positioned at the bottom of the wedge angle piece, the inclination angle range of the wedge angle piece is [10 degrees, 45 degrees ], the inclination angle of the wedge angle piece is the inclined surface of the wedge angle piece and the vertical plane, in an optical path of the slope-adjustable reflection-type MEMS attenuator, light beams emitted by the emergent optical fiber are collimated by the plano-convex lens and then strike on the diffraction grating, the light beams sequentially pass through the diffraction grating and the wedge angle piece, then generate spatial separation and reach the reflecting mirror controlled by MEMS, the spatial positions of the optical paths of the light paths reflected by the reflecting mirror are different, and the received light components of the light beams are different in proportion.

Optionally, the inclination angle of the wedge angle sheet is determined by the line number of the diffraction grating, and the line number of the diffraction grating is in direct proportion to the inclination angle of the wedge angle sheet.

Optionally, the thickness of the wedge angle piece is in the range of [0.1mm,1mm ], and the thickness of the wedge angle piece is the connecting line distance between the midpoint of the inclined plane and the midpoint of the perpendicular plane of the wedge angle piece.

Optionally, the abbe coefficient of the wedge angle piece and the plano-convex lens is less than 30.

Optionally, the wedge angle piece and the plano-convex lens are made of N-SF11.

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

Optionally, the MEMS is configured to control rotation of the mirror about a fixed axis.

Optionally, the slope tunable reflective MEMS attenuator has an operating wavelength range of [1520nm,1575nm ].

According to the specific embodiments provided by the application, the following technical effects are disclosed.

The light beams emitted by the emergent optical fiber are collimated by the plano-convex lens and then are beaten on the diffraction grating, the light beams are spatially separated by the diffraction grating and the wedge angle piece in sequence and reach the reflecting mirror controlled by the MEMS, the spatial positions of the light paths reflected by the reflecting mirror are different, and the proportion of the light components with different wavelengths received by the receiving optical fiber is also different. The key point of the application is that a wedge angle piece with a corresponding angle is arranged behind the diffraction grating, so that partial dispersion compensation is performed in order to generate angular dispersion opposite to the diffraction grating, and the light beam can ensure that the WDL is as small as possible at the minimum insertion Loss point while ensuring that the light beam has larger wavelength dependent Loss (WAVELENGTH DEPENDENT Loss, WDL) at the large insertion Loss point. Based on the reasons, the application realizes the dynamic regulation of the attenuation slope of the reflective MEMS attenuator.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the related art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort to a person having ordinary skill in the art.

FIG. 1 is a side view of an optical path of a slope-adjustable reflective MEMS attenuator provided by an embodiment of the present application.

Fig. 2 is a top view of an optical path of a slope-adjustable reflective MEMS attenuator according to an embodiment of the present application.

FIG. 3 is a graph illustrating attenuation curves corresponding to a slope-adjustable reflective MEMS attenuator according to an embodiment of the present application.

Fig. 4 is a graph of attenuation corresponding to a conventional MEMS attenuator according to an embodiment of the present application.

The symbol is that the optical fiber array-1, the emergent optical fiber-11, the receiving optical fiber-12, the plano-convex lens-2, the diffraction grating-3, the wedge angle sheet-4 and the reflector-5.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.

In order that the above-recited objects, features and advantages of the present application will become more readily apparent, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description.

As shown in fig. 1 and 2, the present embodiment provides a slope-adjustable reflective MEMS attenuator including 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 4, and a mirror 5 (which is controlled by MEMS to rotate around a fixed axis).

The relative positions of the emergent optical fiber 11 and the receiving optical fiber 12 are fixed, the inclined plane of the wedge angle piece 4 faces the diffraction grating 3, the intersection line of the inclined plane of the wedge angle piece 4 and the vertical plane is positioned at the bottom of the wedge angle piece 4, the inclination angle range of the wedge angle piece 4 is [10 degrees, 45 degrees ], the inclination angle of the wedge angle piece 4 is the inclined angle between the inclined plane of the wedge angle piece 4 and the vertical plane, the inclination angle of the wedge angle piece 4 is determined by the line number of the diffraction grating 3, the larger the line number of the diffraction grating 3 is, the inclination angle of the wedge angle piece 4 is larger, the thickness range of the wedge angle piece 4 is [0.1mm,1mm ], and the thickness of the wedge angle piece 4 is the connecting line distance between the inclined plane midpoint of the wedge angle piece 4 and the vertical plane midpoint.

As a preferred embodiment, the abbe coefficient of the wedge angle plate 4 and the plano-convex lens 2 is smaller than 30, the material used for the wedge angle plate 4 and the plano-convex lens 2 is N-SF11, and the scribing density of the diffraction grating 3 is smaller than 100 gr/mm (number of scribing grooves per millimeter).

Further, the optical path composition of the slope-adjustable reflective MEMS attenuator sequentially comprises an emergent optical fiber 11, a plano-convex lens 2, a diffraction grating 3, a wedge angle piece 4, a reflecting mirror 5 and a receiving optical fiber 12. In the optical path of the slope-adjustable reflective MEMS attenuator, the light beam emitted by the emergent optical fiber 11 is collimated by the plano-convex lens 2 and then is applied to the diffraction grating 3, the light beam sequentially passes through the diffraction grating 3 and the wedge angle piece 4 and then is spatially separated and reaches the reflecting mirror 5 controlled by the MEMS, the spatial positions of the optical paths reflected by the reflecting mirror 5 are different, and the proportion of the light components with different wavelengths received by the receiving optical fiber 12 is also different. The period of the diffraction grating 3 and the inclination angle parameters of the wedge angle sheet 4 are matched and designed, so that a quadratic function relationship exists between an Insertion Loss value (IL) and wavelength attenuation, a corresponding relationship exists between the IL and the WDL, and the slope dynamic matching at any Insertion Loss point can be realized by calibrating the relationship between the reflecting mirror angle-IL-d (IL)/dlambda in advance, so that the corresponding WDL value is obtained.

Further, the slope-adjustable reflective MEMS attenuator in this embodiment has an operating wavelength range of [1520nm,1575nm ]. Next, the optimum insertion loss of 1575nm wavelength light is determined based on the above-described slope-adjustable reflective MEMS attenuator.

First, the number of lines of the diffraction grating 3 is set to 20 gr/mm, the thickness of the wedge angle piece 4 is set to 0.3mm, and the inclination angle of the wedge angle piece 4 is set to 11 degrees, so that the optical fiber array 1 is kept fixed (namely, the relative positions of the emergent optical fiber 11 and the receiving optical fiber 12 are fixed).

In the actual working process, the light beam is emitted by the emergent optical fiber 11, collimated by the plano-convex lens 2 and then is applied to the diffraction grating 3, and based on the diffraction principle, the diffraction grating 3 can generate chromatic dispersion (high dispersion capacity) so as to separate the incident light beam in space according to wavelength to form a wavelength-space mapping relation. Specifically, the dispersive power of the diffraction grating 3 is determined by the grating equationDetermining that the angular dispersion rate isWherein d is a grating constant, m is a diffraction order,In order for the incident character to be incident,Is the diffraction angle with the diffraction order of m.

The light beam transmitted through the diffraction grating 3 further enters the wedge angle plate 4, and the wedge angle plate 4 can also disperse the light beam to spatially separate the incident light beam according to wavelengths, but the dispersive power of the wedge angle plate 4 is relatively weak. In particular, the dispersion capacity of the wedge angle piece 4 to the light beam is mainly derived from the refractive index n of the material) The angular dispersion rate is as followsWhere L is the bottom length of wedge 4 and A is the beam cross-sectional area, the dispersive power of diffraction grating 3 is typically 1-2 orders of magnitude higher than wedge 4. Referring to the side view of wedge angle plate 4 in fig. 2, the present embodiment sets the inclination of wedge angle plate 4 from top left to bottom right, and aims to generate angular dispersion opposite to diffraction grating 3, so as to perform partial dispersion compensation, so that the optical beam can ensure that there is a larger WDL at a large insertion loss point and simultaneously ensure that there is a WDL as small as possible at a minimum insertion loss point.

The light beam transmitted through the wedge angle piece 4 reaches the reflecting mirror 5 controlled by the MEMS, and the space position of the light path reflected by the reflecting mirror 5 is different due to the different incident angles of the wavelength components, so that the proportion of the light components with different wavelengths which can be received by the receiving optical fiber 12 is also different, and the proportion of the light with different wavelengths which is received is in nonlinear change. Thus, as the insertion loss increases (i.e., as the mirror 5 rotates through the optimal coupling angle), short wavelength light is not received by the receiving fiber 12 earlier due to the dispersion angle shift, resulting in a steep increase in the slope of the short wavelength band of the attenuation curve.

As shown in FIG. 3, when the initial angle of the MEMS controlled mirror 5 is 10.23 DEG, the optimal insertion loss of 1575nm wavelength is achieved while reaching-0.04 dB, the gradient of WDL curve tends to 0, and when the tilt angle of the MEMS controlled mirror 5 is switched to 10.259 DEG, the attenuation of 1575nm wavelength is-0.45 dB, and at this time, the attenuation of 1520nm wavelength can reach-3.47 dB. Compared with the attenuation effect realized by the traditional MEMS VOA structure of FIG. 4, the application can realize the dynamic regulation and control of the attenuation slope of the reflective MEMS attenuator.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.

The principles and embodiments of the present application have been described herein with reference to specific examples, which are intended to facilitate an understanding of the principles and concepts of the application and are to be varied in scope and detail by persons of ordinary skill in the art based on the teachings herein. In view of the foregoing, this description should not be construed as limiting the application.

Claims

1. A slope-adjustable reflective MEMS attenuator, characterized in that the slope-adjustable reflective MEMS attenuator 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 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 is characterized in that the inclination angle of the wedge piece is determined by the number of lines of the diffraction grating; and the number of lines of the diffraction grating is proportional to the inclination angle of the wedge piece.

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

4 . The reflective MEMS attenuator with adjustable slope according to claim 1 , wherein 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 , wherein 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 , wherein the line density of the diffraction grating is less than 100 gr/mm.

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