阅读说明：本技术 一种平顶型光学滤波器 (Flat-top optical filter ) 是由 白永杰 孔祥君 高军毅 于 2020-06-16 设计创作，主要内容包括：本发明公开了一种平顶型光学滤波器,包括：一分二器件,所述一分二器件包括光谱输入端、第一输出端和第二输出端,所述第一输出端的光谱能量大于或等于第二输出端的光谱能量；MZ元件,所述MZ元件的输入端和第二输出端对接,所述MZ元件用于将第二输出端输出的光谱转换成M型光谱,并将M型光谱通过MZ元件的输出端输出；二合一器件,所述二合一器件包括第一输入端、第二输入端和光谱输出端,所述MZ元件的输出端和第一输入端对接,所述第一输出端和第二输入端对接。能够增加光谱的宽度,进而能够满足WDM器件的光谱宽度要求。本发明应用于光学元件领域。(The invention discloses a flat-top optical filter, comprising: the device comprises a one-to-two device and a control circuit, wherein the one-to-two device comprises a spectrum input end, a first output end and a second output end, and the spectrum energy of the first output end is greater than or equal to that of the second output end; the input end of the MZ element is connected with the second output end in an abutting mode, and the MZ element is used for converting the spectrum output by the second output end into an M-type spectrum and outputting the M-type spectrum through the output end of the MZ element; the two-in-one device comprises a first input end, a second input end and a spectrum output end, wherein the output end of the MZ element is in butt joint with the first input end, and the first output end is in butt joint with the second input end. The spectral width can be increased, and the spectral width requirement of the WDM device can be further met. The invention is applied to the field of optical elements.)

1. A flat-top optical filter, comprising:

the device comprises a one-to-two device and a control circuit, wherein the one-to-two device comprises a spectrum input end, a first output end and a second output end, and the spectrum energy of the first output end is greater than or equal to that of the second output end;

the input end of the MZ element is connected with the second output end in an abutting mode, and the MZ element is used for converting the spectrum output by the second output end into an M-type spectrum and outputting the M-type spectrum through the output end of the MZ element;

the two-in-one device comprises a first input end, a second input end and a spectrum output end, wherein the output end of the MZ element is in butt joint with the first input end, and the first output end is in butt joint with the second input end.

2. The flat-top optical filter according to claim 1, wherein the ratio of the spectral energy of the second output end to the spectral energy of the first output end is 1-3: 5 to 9.

3. The flat-top optical filter according to claim 2, wherein the ratio of the spectral energy of the second output to the spectral energy of the first output is 3: 7.

4. the flat-top optical filter according to claim 1, wherein the two-splitting device is a first Y-branch splitter.

5. The flat-top optical filter according to claim 1, wherein the two-in-one device is a second Y-branch splitter.

Technical Field

The invention relates to the field of optical elements, in particular to a flat-top optical filter.

Background

WDM devices, WDM, Wavelength Division Multiplexer, chinese name Wavelength Division Multiplexer. WDM is a wavelength division multiplexing transmission technology oriented to the metro network access layer. In principle, WDM mixes optical signals with different wavelengths by an optical multiplexer and injects the mixed signals into a single optical fiber for transmission, and at a receiving end of a link, the wavelength-mixed signals in the optical fiber are decomposed into signals with original wavelengths by the optical demultiplexer and connected to corresponding receiving equipment. Most of the existing WDM devices are in a membrane type and a chip type, wherein parameters such as insertion loss isolation degree of a membrane type wavelength division multiplexing scheme and the like are very good, but the insertion loss of a subsequent channel is large due to the cascade structure design of the WDM devices. The chip type is mostly designed by adopting an interference principle, such as an AWG (arrayed waveguide grating) type chip and an MZ (Mach-Zehnder) type chip, the spectrum curve of the chip is Gaussian type or cosine type and is generally called sharp top type spectrum, and the channel bandwidth is not as wide as that of a flat top type device.

Disclosure of Invention

The invention mainly aims to provide a flat-top optical filter which can convert a sharp-top spectrum into a flat-top spectrum, thereby increasing the width of the spectrum and further meeting the requirement of the spectral width of a WDM device.

To achieve the above object, the present invention provides a flat-top optical filter, including:

the device comprises a one-to-two device and a control circuit, wherein the one-to-two device comprises a spectrum input end, a first output end and a second output end, and the spectrum energy of the first output end is greater than or equal to that of the second output end;

the input end of the MZ element is connected with the second output end in an abutting mode, and the MZ element is used for converting the spectrum output by the second output end into an M-type spectrum and outputting the M-type spectrum through the output end of the MZ element;

the two-in-one device comprises a first input end, a second input end and a spectrum output end, wherein the output end of the MZ element is in butt joint with the first input end, and the first output end is in butt joint with the second input end.

In a further improvement, the ratio of the spectral energy of the second output end to the spectral energy of the first output end is 1-3: 5 to 9.

In a further improvement, the ratio of the spectral energy of the second output end to the spectral energy of the first output end is 3: 7.

in a further improvement, the two-splitting device is a first Y-branch splitter.

In a further improvement, the two-in-one device is a second Y-branch splitter.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

the pinnacle spectrum is output from the spectrum input end of the one-to-two device, the pinnacle spectrum is divided into two spectrums by the one-to-two device, and the two spectrums are both pinnacle spectrums. The two light spectrums are respectively output from the first output end and the second output end. The spectral energy output by the first output end is larger than or equal to the spectral energy output by the second output end. The spectrum output from the second output end is input from the input end of the MZ element and is converted into an M-type spectrum through MZ interference, and the M-type spectrum is expressed as: within the input sharp-top spectrum width, a double-sharp-top spectrum with double peak spacing D symmetrical to the original sharp-top spectrum peak is formed, and is similar to a letter M. In the invention, the single-peak peaked spectrum output by the first output end is defined as a spectrum to be converted. The spectrum to be converted is input into the second input end from the first output end, the M-type spectrum is input into the first input end from the output end of the first MZ element, and the M-type spectrum and the spectrum to be converted are superposed to form the converted spectrum through the two-in-one device. When the spectrum is superposed, the energy at two ends of the M-type spectrum can be supplemented to two ends of the spectrum to be converted, the intensity ratio of two paths of light and the double-peak distance D are properly selected, and the superposed converted spectrum becomes a flat-top spectrum. The invention is suitable for carrying out flat-top conversion on the output of the sharp-top type (Gaussian spectrum, cosine spectrum and the like) spectrum device, can increase the width of the spectrum, can directly carry out flat-top conversion on the output of the sharp-top type spectrum device, can be butt-connected at the output end of a WDM chip, and realizes the effect of flat-top of the output spectrum. The flat-top optical filter of the present invention is suitable for various interference type wavelength division chips.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a flat-top optical filter according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a spectral conversion of a flat-top optical filter according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that all the directional indications such as up, down, left, right, front and rear … … in the embodiment of the present invention are only used to explain the relative positional relationship, movement, etc. between the components in a specific posture as shown in the drawings, and if the specific posture is changed, the directional indication is changed accordingly.

In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

Referring to fig. 1 to 2, a flat-top optical filter includes:

the device comprises a one-to-two device 1, wherein the one-to-two device 1 comprises a spectrum input end, a first output end and a second output end, and the spectrum energy of the first output end is greater than or equal to that of the second output end; a two-in-one device 1 is a device that splits a beam of light into two beams. Specifically, the one-to-two device 1 is a first Y-branch optical splitter.

An MZ element 2, an input end of the MZ element 2 is connected to the second output end, the MZ element 2 is configured to convert the spectrum output by the second output end into an M-type spectrum 21, and output the M-type spectrum 21 through the output end of the MZ element 2; the MZ element 2 is a mach-zehnder interference element. The switching principle of the MZ element 2 is: after the spectrum emitted by a single light source is split into two spectra by the MZ element 2, the two spectra pass through different paths and media to generate relative phase shift change, so that the intensity of the two spectra after interference superposition is different, and the spectrum scanning curve is a cosine curve generated based on phase delay. This function is achieved in the MZ element 2 by two waveguides of unequal arm length. By adjusting the difference in the lengths of the two arms, the output light spectrum of the MZ element 2 can be controlled to be "M" type.

Specifically, a spectrum emitted by a single light source is first divided into two halves by a Y-branch splitter, and the light fields of the two divided spectra are expressed as: 0.5 sin x, the difference in the lengths of the two arms is L, and the refractive index is n, so the optical path difference can be expressed as n x L. For different wavelengths lambda, their phase difference

Phi ═ (n × L)% λ × 2 pi, where% is the remainder.

The interference results are:

0.5*sinx+0.5*sin*(x+φ)

after simplification, is

Wherein，

The two-in-one device 3 comprises a first input end, a second input end and a spectrum output end, the output end of the MZ element 2 is in butt joint with the first input end, and the first output end is in butt joint with the second input end. The two-in-one device 3 is a device that combines two light spectra into one beam. Specifically, the two-in-one device 3 is a second Y-branch optical splitter. The first and second Y-branch splitters are the same element, except that the first Y-branch splitter splits the spectrum and the second Y-branch splitter combines the two spectra. The second Y-branch splitter is the reverse application, i.e., retro-fitted, of the first Y-branch splitter.

The working principle of the flat-top optical filter of the embodiment is as follows:

the pinnacle spectrum is output from the spectrum input end of the one-to-two device 1, and is divided into two spectrums by the one-to-two device 1, wherein the two spectrums are both pinnacle spectrums. The two light spectrums are respectively output from the first output end and the second output end. The spectral energy output by the first output end is larger than or equal to the spectral energy output by the second output end. The spectrum output from the second output terminal is input from the input terminal of the MZ element 2, and is converted into an M-type spectrum 21 by the MZ interference 2, where the M-type spectrum 21 is represented as: within the input sharp-top spectrum width, a double-sharp-top spectrum with double peak spacing D symmetrical to the original sharp-top spectrum peak is formed, and is similar to a letter M. In this embodiment, the single-peak peaked spectrum output by the first output terminal is defined as the spectrum 11 to be converted. The spectrum 11 to be converted is input into the second input end from the first output end, the M-type spectrum 21 is input into the first input end from the output end of the first MZ element 2, and the M-type spectrum 21 and the spectrum 11 to be converted are superposed to form a converted spectrum 31 through the two-in-one device 3. When the spectrum is superimposed, the energy at the two ends of the M-type spectrum 21 can be supplemented to the two ends of the spectrum 11 to be converted, the intensity ratio of the two lights and the double-peak distance D are properly selected, and the superimposed converted spectrum 31 becomes a flat-top spectrum.

Preferably, the ratio of the spectral energy of the second output end to the spectral energy of the first output end is 1-3: 5 to 9. The peaked spectrum is divided into two unequal spectra by a dichotomy device 1. Further preferably, the ratio of the spectral energy of the second output end to the spectral energy of the first output end is 3: 7. the wavelength of the center of the sharp-top spectrum input from the spectrum input end is 1271nm, the bandwidth of 0.5dB (dB is a mathematical calculation, namely-10 log X.0.5 dB bandwidth is a common evaluation index, namely the bandwidth width when the energy is reduced to 89% of the peak value) is 8nm, the measurement index is 0.5dB bandwidth of a WDM common evaluation index, and the standard requirement in the industry is 13 nm. The flat-top optical filter of the present embodiment can meet the standard.

When an appropriate optical path difference is selected, 1.271 × 20.5, wherein phi is equal to pi, the superposition amplitude of the two optical fields is 0, namely the energy value at 1271nm is 0. The input light 1271nm of the MZ interference structure has the largest energy, after passing through the MZ interference structure, the energy at 1271nm is reduced to 0, the left side and the right side of 1271nm are not 0, and the spectrum shape of the MZ interference structure is approximate to an M type.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.