WO2012092871A2

WO2012092871A2 - Adjustable optical filtering device and method for adjustable optical filtering

Info

Publication number: WO2012092871A2
Application number: PCT/CN2012/070078
Authority: WO
Inventors: 王衡; 徐之光
Original assignee: 华为技术有限公司
Priority date: 2012-01-05
Filing date: 2012-01-05
Publication date: 2012-07-12
Also published as: CN102884455A; WO2012092871A3

Abstract

Embodiments of the present invention provide an adjustable optical filtering device characterized by comprising: a magnetostrictive module, a filtering module, and a magnetic field provision module, the magnetostrictive module and the filtering module adhering one to the other, and the magnetic field provision module acting on the magnetostrictive module; the magnetostrictive module undergoes deformation by changing its own area or volume under the effect of a magnetic field; the filtering module changes its own length of same according to the deformation of the magnetostrictive module, thereby changing the cycle size of the filtering module. Embodiments of the present invention also provide a method for adjustable optical filtering.

Description

Tunable optical filtering device and method for realizing tunable optical filtering

The present invention relates to fiber optic communication technology, and more particularly to a tunable optical filtering device and a method of implementing tunable filtering.

Background technique

The tunable optical filter has extensive and profound applications in optical fiber communication technology. For example, the tunable optical filter can be applied to wavelength division multiplexing demultiplexing to form a reconfigurable optical add/drop optical monitor. It is used in tuning transmitters and receivers to suppress spontaneous emission, and can also be applied to optical switches with high "switching ratio".

The optical filters currently used can be classified into different types based on fiber gratings, Mach-Zehnder interferometers, and integrated arrayed waveguide gratings. However, the cost and wavelength tuning range has plagued the further development of tunable filters. Conventional optical filters that are directly tuned by temperature can only achieve a small tuning range due to the limitation of the actual material tuning range; optical filters that achieve fiber grating wavelength tuning by changing the axial stress of the fiber grating, although Achieve a wide range of tuning and faster response speed, but it also has its inherent shortcomings; the existing tunable optical filter structure is relatively large, and is an active device, comprehensive consideration and wavelength division multiplexing passive optical network The difficulty of combining semiconductor amplifiers requires a passive, tunable, and low-cost filter component in real-world applications.

Summary of the invention

The present invention provides a tunable optical filtering device and a method for implementing tunable filtering, in order to solve the problem that a passive, adjustable, and low-cost filter device is required in the above-mentioned practical application.

The tunable optical filter device provided by the embodiment of the present invention includes: a magnetostrictive module, a filtering module, and a magnetic field providing module, wherein the magnetostrictive module is bonded to the filtering module, and the magnetic field providing module provides a magnetic field acting on the magnetostrictive module; the magnetostrictive module for deforming by changing an area or volume of a magnetic field force; the filtering module for deforming according to the magnetostrictive module And change the length of itself to change the filter module week The size of the period.

The method for implementing tunable optical filtering provided by the embodiment of the present invention includes: changing an area or a volume of a magnetostrictive module subjected to a magnetic field force to deform the magnetostrictive module; and deforming according to the magnetostrictive module The length of the filtering module in turn changes the size of the filtering module period.

The tunable optical filter device and the tunable optical filtering method provided by the embodiment of the present invention change the length of the filter module by changing the size or volume of the magnetostrictive force of the magnetostrictive module, and finally change the filter module. The cycle size achieves the goal of adjusting the filter module period under passive low-cost conditions.

DRAWINGS

1 is a schematic structural diagram of a tunable optical filter device according to an embodiment of the present invention; FIG. 2 is a schematic structural diagram of another tunable optical filter device according to an embodiment of the present invention;

The embodiment of the present invention provides a tunable optical filtering device based on the above-mentioned shortcomings existing in the existing tunable optical filter technology and the actual requirements of the tunable optical filter.

The tunable optical filter device provided by the embodiment of the invention utilizes the characteristics of the magnetostrictive material in the magnetic field and the Bragg grating to achieve passive, low-cost and other technical effects.

The magnetostrictive material has a magnetostrictive effect, and the so-called magnetostrictive effect means that the magnetostrictive material changes its length and volume when the magnetic field force it receives changes. The magnetostriction of magnetostrictive materials is divided into two categories: linear magnetostriction and bulk magnetostriction. When the magnetostrictive material is deformed by the magnetic field force, its deformation is carried out along a certain linear direction, and when the magnetostrictive material is deformed by the magnetic field force, the entire volume expands or contracts, and the deformation direction quite complicated. On the other hand, magnetostriction can be divided into positive magnetostriction and reverse magnetostriction. The positive magnetostriction is that the length of the magnetic material increases with the increase of the magnetic field force, and the reverse magnetostriction is The length of the magnetic material decreases as the force of the magnetic field increases. The following examples A tunable optical filter device using a linear magnetostrictive material is taken as an example.

When the area or volume of the linear magnetostrictive material is exposed to the magnetic field, the deformation of the linear magnetostrictive material when subjected to a magnetic field of a certain intensity is also different, and the embodiment of the present invention utilizes the feature of the linear magnetostrictive material and The object of the invention is achieved in combination with its inherent characteristic of deformation in a particular linear direction.

Specifically, as shown in FIG. 1, a tunable optical filtering apparatus according to an embodiment of the present invention includes a magnetic ring 101, a linear magnetostrictive material 102, and a Bragg grating 103. The Bragg grating 103 is pasted on the center line of the in-line magnetostrictive material 102, the extending direction of the Bragg grating 103 is the same as the direction in which the magnetostrictive material 102 is stretched, and the magnetic ring 101 is located on the line magnetostrictive material to which the Bragg grating 103 is adhered. The periphery of 102 provides a magnetic field for at least a portion of the linear magnetostrictive material 102. For example, the magnetic ring 101 can define a receiving space. The inside of the receiving space has a magnetic field under the action of the magnetic ring 101. The magnetostrictive material 102 can be partially received in the receiving space provided by the magnetic ring 101, so as to be adhered to the magnetic body. The Bragg grating 103 of the stretchable material 102 partially enters the magnetic field region. By mechanically adjusting the length of the magnetic field region provided by the magnetostrictive material 102 into the magnetic ring, the length of the linear magnetostrictive material changes accordingly, and the Bragg grating attached thereto changes when the length of the linear magnetostrictive material changes. The length of 103 is finally adjustable to achieve the Bragg grating period. In addition, in the above structure, a portion of the magnetostrictive material 102 and the Bragg grating 103 on its surface does not enter the receiving space of the magnetic ring 101, in order to protect the portion of the magnetostrictive material 102 and the Bragg grating 103, in a specific embodiment The edge of the magnetic ring 101 may also be provided with a non-magnetic material. The non-magnetic material may also have an annular structure and be disposed on the periphery of the receiving space magnetostrictive material 102 and the Bragg grating 103 that do not enter the magnetic ring 101.

In a specific application, the Bragg grating 103 may be a fiber Bragg grating (FBG) etched on the optical fiber, and the magnetic ring 101 is located at the periphery of the fiber etched with the Bragg grating as the Bragg grating 103. Providing a magnetic field, the linear magnetostrictive material linearly deforming in a direction along the optical fiber, causing the non-magnetic stretchable material to linearly deform in the direction of the optical fiber, and stretching or reducing the etching in the optical fiber direction in the optical fiber The length of the upper Bragg grating 103, The period of the Bragg grating 103 is adjustable.

Specifically, in the case where the linear magnetostrictive material 102 is a positive magnetostrictive material, when the length of the linear magnetostrictive material 102 entering the magnetic field region becomes large, the linear magnetostrictive material 102 receives a magnetic field. The area of the force will increase, causing the linear magnetostrictive material 102 to stretch in the centerline direction, thereby causing the length of the Bragg grating 103 pasted thereon to become larger along the centerline direction, ultimately resulting in a Bragg grating. The period of 103 becomes larger; when the length of the linear magnetostrictive material 102 entering the magnetic field region becomes smaller, the area of the magnetostrictive material 102 subjected to the magnetic field force is reduced, thereby causing the line magnetostrictive material 102 to The direction of the center line is reduced, which in turn causes the length of the Bragg grating 103 pasted thereon to become smaller along the center line direction, eventually making the period of the Bragg grating 103 smaller.

In the case where the linear magnetostrictive material 102 is a reverse magnetostrictive material, when the length of the linear magnetostrictive material 102 entering the magnetic field region becomes large, the area of the linear magnetostrictive material 102 subjected to the magnetic field force Will increase, thereby causing the linear magnetostrictive material 102 to shrink in the center line direction, thereby causing the length of the Bragg grating 103 pasted thereon to become smaller along the center line direction, and finally making the period of the Bragg grating 103 smaller; When the length of the linear magnetostrictive material 102 entering the magnetic field region becomes small, the area of the linear magnetostrictive material 102 subjected to the magnetic field force becomes large, thereby causing the linear magnetostrictive material 102 to stretch in the center line direction. Further, the length of the Bragg grating 103 pasted thereon is increased in the center line direction, and finally the period of the Bragg grating 103 is increased.

The change of the Bragg grating period will cause the center wavelength of the Bragg grating to drift, and the wavelength allowed by the filter will also drift, thus adjusting the filtering.

Another tunable optical filter device provided by the embodiment of the present invention adopts the structure shown in FIG. Specifically, the structure shown in FIG. 2 includes a magnetic ring 201, a pigtail grating 202 with pigtails, a non-magnetic stretchable material 203, and a linear magnetostrictive material 204, wherein the non-magnetic stretchable material 203 is subjected to an external force. The impact of the expansion performance is better. As shown in FIG. 2, a linear magnetostrictive material 204 is located inside the non-magnetic stretchable material 203, and both ends of the pigtailed grating of the pigtailed grating 202 are separated. Do not stick to the two bonding points of the non-magnetic stretchable material 203, and the magnetic ring 201 is located around the linear magnetostrictive material 204 to provide a magnetic field to the linear magnetostrictive material 204. The volume of the magnetic field region provided by the magnetic ring is adjusted by mechanical means to enter the volume of the magnetic field region provided by the magnetic ring, thereby changing the volume of expansion and contraction of the linear magnetostrictive material 204. When the linear magnetostrictive material 204 changes volume in a specific linear direction, The deformation of the non-magnetic stretchable material 203 surrounding it is caused in a specific linear direction, and the deformation of the non-magnetic stretchable material 203 changes the length of the fiber-optic Bragg grating 202, and finally the Bragg grating 202 is realized. The cycle is adjustable. In a specific application, the Bragg grating 202 may be etched on the optical fiber, and the two end points of the Bragg grating 202 are respectively pasted on the non-magnetic expandable material 203, and the linear magnetostrictive material 204 is along the optical fiber. The direction is linearly deformed, causing the non-magnetic stretchable material 203 to linearly deform in the direction of the optical fiber, and the length of the Bragg grating 202 etched on the optical fiber is stretched to realize the period of the Bragg grating 103.

Specifically, in the case where the linear magnetostrictive material 204 is a positive magnetostrictive material, when the volume of the magnetic field region provided by the linear magnetostrictive material 204 into the magnetic ring 201 becomes large, the magnetic line is magnetic The strength of the stretchable material 204 is increased by the force of the magnetic field, thereby causing the volume of the linear magnetostrictive material 204 to become larger in a certain linear direction, thereby pushing the volume of the nonmagnetic stretchable material 203 surrounding it. Increasing in a particular linear direction causes the length of the Bragg grating 202 bonded to the non-magnetic stretchable material 203 to increase in a particular linear direction, ultimately achieving adjustment of the Bragg grating 202 period; When the volume of the magnetostrictive material 204 entering the magnetic field region provided by the magnetic ring 201 becomes small, the strength of the linear magnetostrictive material 204 by the magnetic field force becomes small, thereby causing the volume of the linear magnetostrictive material 204 to follow a certain volume. The specific linear direction becomes smaller, which in turn causes the volume of the non-magnetic stretchable material 203 surrounding it to become smaller in a certain linear direction, resulting in bonding The length of the Bragg grating 202 of the non-magnetic stretchable material 203 becomes smaller in a certain linear direction, ultimately achieving adjustment of the Bragg grating 202 period.

In the case where the linear magnetostrictive material 204 is a reverse magnetostrictive material, when the line magnetism When the volume of the stretchable material 204 entering the magnetic field region provided by the magnetic ring 201 becomes large, the linear magnetostrictive material 204 is subjected to an increase in the strength of the magnetic field force, thereby causing the volume of the linear magnetostrictive material 204 to follow a certain volume. The particular linear direction becomes smaller, which in turn causes the volume of the non-magnetic stretchable material 203 surrounding it to decrease in a particular linear direction, resulting in the length of the Bragg grating 202 bonded to the non-magnetic stretchable material 203. Zooming in a certain linear direction, finally adjusting the period of the Bragg grating 202; when the volume of the magnetic field region provided by the linear magnetostrictive material 204 into the magnetic ring 201 becomes small, the linear magnetostrictive material 204 is subjected to a magnetic field The strength of the force becomes small, causing the volume of the linear magnetostrictive material 204 to become larger in a certain linear direction, thereby pushing the volume of the non-magnetic stretchable material 203 surrounding it to change in a certain linear direction. Large, causing the length of the Bragg grating 202 bonded to the non-magnetic stretchable material 203 to become larger in a certain linear direction, ultimately achieving Bragg light 202 adjustment period.

Further, considering the characteristics of the magnetostrictive material itself, that is, the length of the magnetostrictive material can be divided into two parts by the variation of the magnetic field strength. The first part is a linear interval in which the magnetostrictive material increases linearly or linearly with increasing magnetic field strength; the other part is a nonlinear region, also called a saturated region, in which magnetostrictive material The length does not change as the strength of the magnetic field increases. When the magnetic field strength reaches saturation, the telescopic length of the magnetostrictive material reaches the maximum or minimum saturation. The value of the magnetic field strength when the magnetic field strength is saturated is called the magnetic field strength saturation coefficient. Different magnetostrictive materials have different magnetic field strength saturation coefficients due to their different structural characteristics.

In general, a linear section of a magnetostrictive material is used to provide a magnetic field to the magnetostrictive material, but in the embodiment of the invention, we apply a magnetic ring to provide a magnetic field to the magnetostrictive material, due to the inherent characteristics of the magnetic ring, When the magnetic ring is used for a time, the magnetic field strength provided by the magnetic ring becomes smaller with time. If the magnetic field is supplied to the magnetostrictive material according to the variation of the linear interval, the tensile force is the same as the magnetic field strength is reduced. Distance or volume will result in tuning The range changes, causing inconsistencies in the tuning range. In view of the above reasons, the embodiment of the present invention considers the saturation characteristic of the magnetostrictive material, and uses the magnetic ring to provide the magnetostrictive material with a magnetic field having an eternal magnetic field strength, which is greater than the magnetic field strength saturation coefficient of the linear magnetostrictive material. In this way, the magnetostrictive material will always work in the saturation interval. As the working time increases, the magnetic field strength decreases, but it is still in the saturated working interval of the magnetostrictive material. The performance of the filtering device is not affected.

The tunable optical filter device provided by the embodiment of the present invention mechanically changes the volume of the magnetostrictive material in the magnetic field, thereby changing the length of the Bragg grating, and finally changing the period of the Bragg grating, thereby achieving a passive low Cost tunable filtering device.

Based on the tunable optical filtering device provided by the foregoing embodiment, the embodiment of the present invention further provides a method for implementing tunable optical filtering. As shown in FIG. 3, the method includes:

Step 301: changing an area or a volume of the magnetostrictive module subjected to a magnetic field to deform the magnetostrictive module;

A part of the magnetostrictive module is placed in a magnetic field provided by the magnetic field providing module, and the area or volume of the magnetostrictive module subjected to the magnetic field force is changed, causing the magnetostrictive module to be changed by the magnitude of the magnetic field force, thereby causing The magnetostrictive module is deformed.

The magnetostrictive module may be the linear magnetostrictive material 102 of FIG. 1, or may be a combination of the linear magnetostrictive material 204 and the non-magnetic stretchable material 203 of FIG. 2; the above acting on the magnetostrictive module The magnetic field can be provided by the magnetic ring shown in Figures 1 and 2.

Step 302: Change the length of the magnetostrictive module according to the deformation of the magnetostrictive module to change the period of the filtering module.

Since the magnetostrictive module is deformed, the length of the filter module attached to the magnetostrictive module changes accordingly. Due to the structural characteristics of the filter module, the change of the length of the filter module eventually causes the cycle of the filter module to change. .

The filtering module may be the Bragg grating 103 of FIG. 1 or the Bragg grating 202 of the pigtail of FIG. In this embodiment, when the magnetostrictive module is a positive magnetostrictive material, the size of the filter module period is proportional to the size or volume of the magnetostrictive module subjected to the magnetic field force; when magnetostriction When the module is an inverse magnetostrictive material, the size of the filter module period is inversely proportional to the size of the area or volume of the magnetostrictive module subjected to the magnetic field force.

In an embodiment, the magnetostrictive module may be a linear magnetostrictive material, the filtering module may be a Bragg grating, and the magnetic field is provided by a magnetic ring; changing the linear magnetostrictive material by the magnetic The area of the magnetic field provided by the ring causes the linear magnetostrictive material to undergo linear deformation; the length of the Bragg grating is changed according to the linear deformation of the linear magnetostrictive material, thereby changing the size of the Bragg grating period.

In another case, the magnetostrictive material may be a combination of a linear magnetostrictive material and a non-magnetic stretchable material, and the filtering module may be a Bragg grating, and the magnetic field is provided by a magnetic ring; The linear magnetostrictive material is subjected to a magnetic field provided by the magnetic ring to cause linear deformation of the linear magnetostrictive material; and the non-magnetic stretchable according to linear deformation of the linear magnetostrictive material The material undergoes linear deformation; the length of the Bragg grating is varied according to the linear deformation of the non-magnetic stretchable material, thereby changing the period of the Bragg grating.

In a specific application scenario, the Bragg grating in the above two cases can be etched on the optical fiber, and the magnetic field strength provided by the magnetic ring can always be greater than the linear magnetostrictive material in order to ensure the constantity of the periodic adjustment of the filtering module. The saturation coefficient of the magnetic field strength.

The tunable optical filtering method provided by the embodiment of the invention can change the length of the filtering module by first deforming the magnetostrictive material, and finally realize the change of the filtering module period, and the adjustable effect of the period is achieved.

The above is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope of the present disclosure. Alternatives are intended to be covered by the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Claim

A tunable optical filter device, comprising: a magnetostrictive module, a filtering module, and a magnetic field providing module, wherein the magnetostrictive module is bonded to the filtering module, and the magnetic field providing module Providing a magnetic field acting on the magnetostrictive module;

The magnetostrictive module for deforming by changing an area or volume of a magnetic field force;

The filtering module is configured to change the length of the filter module according to the deformation of the magnetostrictive module to change the size of the filter module period.

2. The tunable filtering device of claim 1, wherein a size of the filter module period is proportional to at least one of an area or a volume of the magnetostrictive module that is subjected to a magnetic field force.

The tunable filter device according to claim 2, wherein when the magnetostrictive module is a positive magnetostrictive material, the size of the filter module period and the magnetostrictive module are subjected to a magnetic field At least one of the area or volume of the force is proportional;

When the magnetostrictive module is a magnetostrictive material, the size of the filter module period is inversely proportional to at least one of an area or volume of the magnetostrictive module that is subjected to a magnetic field force.

The tunable optical filter device according to claim 1, wherein the magnetostrictive module is a linear magnetostrictive material, the filtering module is a Bragg grating, and the magnetic field providing module is a magnetic ring;

Wherein the Bragg grating is adhered to a center line of the linear magnetostrictive material, the direction is consistent with a direction in which the linear magnetostrictive material is stretched, and the magnetic rings are respectively located on the surface of the Bragg grating Both sides of the line magnetostrictive material.

5. The tunable filtering device according to claim 1, wherein the magnetostrictive module comprises a linear magnetostrictive material and a non-magnetic stretchable material, and the filtering module is a pigtail with a pigtail. a grating, the magnetic field providing module is a magnetic ring; Wherein the linear magnetostrictive material is located in the non-magnetic stretchable material, and the two ends of the pigtailed Bragg grating are respectively bonded to the non-magnetic pullable by two bonding points. At both ends of the material port, the magnetic ring is located on both sides of the line magnetostrictive material to provide a magnetic field to the line magnetostrictive material.

6. The tunable filtering device of claim 4 or 5, wherein the Bragg grating is etched on the optical fiber.

The tunable optical filter device according to any one of claims 4 to 5, wherein the magnetic ring provides a magnetic field strength greater than a magnetic field strength saturation coefficient of the linear magnetostrictive material.

8. A method for implementing tunable filtering, the method comprising:

Changing the area or volume of the magnetostrictive module subjected to a magnetic field to deform the magnetostrictive module;

The length of the filter module is changed according to the deformation of the magnetostrictive module to change the size of the filter module period.

9. The method of implementing tunable filtering of claim 8, wherein the size of the filter module period is proportional to at least one of an area or volume of the magnetic field force.

10. The method for implementing tunable filtering according to claim 8, wherein when the deformation is proportional to the area or volume of the magnetic field force, the size of the filter module period and the magnetic field At least one of the area or volume of force is proportional to;

When the deformation is inversely proportional to the area or volume of the magnetic field acting force, the magnitude of the filtering module period is inversely proportional to at least one of the area or volume of the magnetic field acting force.

11. A tunable filter, comprising: a magnetic element, a magnetostrictive material, and a fiber Bragg grating, at least a portion of the magnetostrictive material being movably disposed in a magnetic field region provided by the magnetic device, a fiber Bragg grating and the magnetostrictive material are bonded to each other; wherein the magnetostrictive material passes through a shape when an area thereof enters the magnetic field region changes The length of the fiber Bragg grating is changed accordingly.

The tunable filter according to claim 11, wherein the fiber Bragg grating is pasted on the magnetostrictive material, and an extending direction of the fiber Bragg grating and a pulling of the magnetostrictive material The extension direction is the same.

The tunable filter according to claim 11, further comprising a non-magnetic stretchable material, wherein the non-magnetic stretchable material is disposed on a periphery of the magnetostrictive material, the magnetic A stretchable material is bonded to both sides of the fiber Bragg grating by the non-magnetic stretchable material.