CN115390293A - Multi-passband liquid crystal tunable filtering method applied to laser communication - Google Patents

Multi-passband liquid crystal tunable filtering method applied to laser communication Download PDF

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CN115390293A
CN115390293A CN202211342502.3A CN202211342502A CN115390293A CN 115390293 A CN115390293 A CN 115390293A CN 202211342502 A CN202211342502 A CN 202211342502A CN 115390293 A CN115390293 A CN 115390293A
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cascade
liquid crystal
transmission peak
wavelength
main transmission
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CN115390293B (en
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董科研
李欣航
刘超
宋延嵩
张博
朴明旭
梁宗林
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Changchun University of Science and Technology
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers

Abstract

The invention particularly relates to a multi-passband liquid crystal tunable filtering method applied to laser communication, which comprises the steps of determining the first cascade liquid crystal delay of a main transmission peak by selecting proper optical parameters, calculating the wavelength of a carried peak value and the delay of other cascade liquid crystals according to the delay difference of the first cascade liquid crystals, verifying whether the carried transmission peak is extremely large in interference at the other cascade, adjusting external signals of the liquid crystals by software according to the delay of all cascade liquid crystals if the interference is extremely large to realize multi-passband spectral output, and finally realizing that a plurality of transmittance peaks with mutually separated wavelengths are generated at a visible/near-infrared band simultaneously. The invention has the advantages of carrying transmission peak output while outputting the main transmission peak, obviously reducing the cascade quantity under the condition of not sacrificing the passband width of the main transmission peak, having higher spectral energy output and reducing the signal-to-noise ratio on the premise of meeting the channel switching in the laser communication application process.

Description

Multi-passband liquid crystal tunable filtering method applied to laser communication
Technical Field
The invention relates to the technical field of laser communication, in particular to a multi-passband liquid crystal tunable filtering method applied to laser communication.
Background
The laser communication networking technology is an important means for constructing a space integrated network layout and is also a main development direction of space laser communication in the future. The main optical transceiver and the plurality of sub optical transceivers included in the space networking system need spectral information of different spectral bands in order to successfully complete the functions of target searching, identifying, tracking and aiming and information exchange.
The liquid crystal tunable optical filter takes liquid crystal as an electric control tunable optical material and has important application in the technical field of laser communication. The method can be used for realizing the switching of communication channels and the selection of spectral channels in the technical field of laser communication. The tunable optical filter has various types, and the tunable optical filter based on the liquid crystal birefringence effect and the electro-optic effect has the advantages of continuous tuning, wide tuning range, large clear aperture, high reliability and the like. However, currently, the existing tunable liquid crystal filter mainly has Lyot type and Solc type, and the Lyot type has the advantages of wide tuning range, high spectral resolution and small installation and tuning error compared with the Solc type, but the traditional Lyot type liquid crystal tunable filter is output with a single passband wavelength, and the output energy cannot meet the requirement of communication information exchange.
Disclosure of Invention
Therefore, the technical problem to be solved by the present invention is to overcome the defect that the output energy of the traditional Lyot type liquid crystal tunable filter is not capable of meeting the communication information exchange requirement when the traditional Lyot type liquid crystal tunable filter is output with a single passband wavelength, thereby providing a multi-passband liquid crystal tunable filtering method applied to laser communication.
A multi-passband liquid crystal tunable filtering method applied to laser communication comprises the following steps:
s1: the initial parameters are determined and the initial parameters,determining the number m of transmission peaks and the wavelength of a main transmission peak which are generated in the visible band and the near infrared band while the wavelengths are separated from each otherλ 0 (may be written as
Figure 40462DEST_PATH_IMAGE001
）；
S2: setting cascade initial conditions, wherein the cascade comprises two polaroids and a liquid crystal, transmission optical axes of the two polaroids are parallel to each other, an included angle between the optical axis direction of the two polaroids and the o-ray vector direction of the liquid crystal is 45 degrees, and determining the light transmittance of a single cascade according to a formula;
s3: setting N cascades with the same cascade structure as the cascade structure in the step S2, and determining the total light transmittance of the N cascades according to a formula;
s4: calculating the retardation of each cascade liquid crystal, setting the position of a main transmission peak as an interference maximum value according to an interference principle to obtain the retardation required to be introduced into each stage of cascade liquid crystal, wherein the retardation required to be introduced into each stage of cascade liquid crystal is obtained according to the following formula:
Figure 563104DEST_PATH_IMAGE002
；
s5: and adjusting the external electric signal of the liquid crystal, adjusting the voltage value applied to the outside of each cascade liquid crystal through software according to the retardation of each level of liquid crystal, and driving the optical parameters of the liquid crystal to change so as to realize multi-passband spectral output.
Further, the step S4 specifically includes:
s4.1: the number m of the transmission peaks and the wavelength lambda of the main transmission peak determined in the step S1 are calculated 0 Substituting into a retardation formula, and calculating the retardation delta of the first cascade liquid crystal 1 ；
S4.2: calculating the wavelength of the first cascade carried transmission peak
Figure 79667DEST_PATH_IMAGE003
The first cascade carries a number of transmission peak wavelengths of
Figure 93759DEST_PATH_IMAGE004
According to the steps ofRetardation δ obtained in step S4.1 1 Calculating the interference order of
Figure 409072DEST_PATH_IMAGE005
First cascade of time carrying transmission peak wavelength
Figure 601150DEST_PATH_IMAGE003
Wherein k is more than or equal to 1 and less than m.2 N-1 A positive integer of (d);
s4.3: calculating the delay amount of the rest cascaded liquid crystals, repeating the step S4.2, calculating and judging the wavelength of the main transmission peakλ 0 And the first cascade carries the wavelength of the transmission peak
Figure 588697DEST_PATH_IMAGE003
Whether or not there is an interference maximum in the liquid crystal.
Furthermore, the main transmission peak and the first cascade carried transmission peak are staggered, and an interband gap for inhibiting light transmission is arranged between the main transmission peak and the first cascade carried transmission peak.
Further, the main transmission peak wavelengthλ 0 The bandwidth is narrowest, the first cascade carries the wavelength of the transmission peak along with the distance from the wavelength of the main transmission peakλ 0 The degree is wider and wider, and the transmission energy is larger and larger.
Further, in the method, different main transmission peaks are accompanied by the same number of carrying transmission peaks, and the positions of the carrying transmission peaks are integrally translated along with the change of the positions of the main transmission peaks.
Further, the light transmittance of the single cascade is:
Figure 387239DEST_PATH_IMAGE006
(i =1,2, \8230;), i being the number of cascade layers;
wherein the content of the first and second substances,
Figure 776632DEST_PATH_IMAGE007
is the amount of phase retardation of the liquid crystal,
Figure 670770DEST_PATH_IMAGE008
。
further, the total transmittance of the N cascades is:
Figure 660461DEST_PATH_IMAGE009
。
an electronic device comprising a memory storing a computer program and a processor implementing the steps of any of the above methods when the processor executes the computer program.
A computer readable storage medium storing computer instructions which, when executed by a processor, implement the steps of any of the above methods.
In the technical scheme of the invention, the main transmission peak output is accompanied with the transmission peak output, and the cascade quantity can be obviously reduced under the condition of not sacrificing the width of a pass band, thereby effectively improving the spectrum output energy on the premise of meeting channel switching and meeting the requirement of communication information exchange; in the technical scheme of the invention, the output multi-passband peaks can be effectively staggered, and interband gaps for inhibiting light transmission are generated between passbands, so that the switching requirement of communication channels is ensured; in the technical scheme of the invention, the main transmission wavelength bandwidth is narrowest, the degree of the transmission wavelength carried with the main wavelength becomes wider and wider along with the distance from the main wavelength, and the transmitted spectral energy is larger; in addition, different main transmission peaks are accompanied by the same number of carrying transmission peaks, and the carrying transmission peak positions are integrally translated along with the change of the main transmission peak positions, so that the modulation coverage of a wide spectrum band is realized.
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, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a flow chart of a method embodying the present invention;
FIG. 2 is a schematic diagram of polarization interference of light beams in cascade
FIG. 3 is a graph of transmittance of a 3-pass band liquid crystal tunable filter;
FIG. 4 is a graph of transmittance of a 2-pass band liquid crystal tunable filter;
FIG. 5 is a graph of transmittance of a multi-band liquid crystal tunable filter with different main transmission wavelengths.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. 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.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Furthermore, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example 1
A multi-passband liquid crystal tunable filtering method applied to laser communication comprises the following steps:
s1: determining initial parameters, determining the number m of transmission peaks separated from each other in visible and near infrared bands, and the wavelength of the main transmission peak as 3λ 0 Is 400nm;
s2: setting cascade initial conditions, wherein the cascade comprises two polaroids and a liquid crystal, a light source emits a wide-band light beam, and the light beam passes through the polaroids P 1 The linearly polarized light after the action enters the liquid crystal A, the light wave is decomposed into two coherent polarized lights, and the two coherent polarized lights are emitted to the polaroid P 2 The principle of the polarized interference is shown in FIG. 2, and a polarizer P is provided 1 And P of 2 Of the liquid crystal A are parallel to each otheroThe included angle between the light vector direction and the transmission axis direction of the polaroid is 45 degrees, and the transmission rate of the light beam after single cascade connection can be expressed as follows:
Figure 298247DEST_PATH_IMAGE006
(i =1,2, \8230;) i is the number of cascade layers (1);
wherein the content of the first and second substances,
Figure 591081DEST_PATH_IMAGE007
is the amount of phase retardation of the liquid crystal,
Figure 452858DEST_PATH_IMAGE010
；n e is the refractive index of the e-light of the liquid crystal,n o is the refractive index of the o light of the liquid crystal,d i is the cascaded liquid crystal thickness;
s3: three cascades having the same cascade structure as the cascade structure in the step S2 were set, and the total transmittance after three single-cascade was expressed as:
Figure 195424DEST_PATH_IMAGE011
（2）；
s4: calculating the retardation of each cascade liquid crystal, setting the position of a main transmission peak as an interference maximum value according to an interference principle to obtain the retardation required to be introduced into each stage of cascade liquid crystal, wherein the retardation required to be introduced into each stage of cascade liquid crystal is obtained according to the following formula:
Figure 371321DEST_PATH_IMAGE002
，（3）；
in the formula, N is the cascade number;
calculating the retardation of each cascade liquid crystal according to the formula (3), and calculating the transmission peak which appears when the light beam singly passes through the Nth cascade liquid crystal:
Figure 266465DEST_PATH_IMAGE012
（4）
and judging the rationality of design of all cascade delay amounts, wherein all transmission peaks of the first cascade liquid crystal, namely a main transmission peak and a carrying transmission peak, are considered to be capable of realizing multi-passband filtering when all the other cascade liquid crystals are transmission peaks, and the rationality is as follows:
s4.1: calculating the retardation of the first cascade liquid crystal according to the formula (3)δ 1 Is 1200nm;
s4.2: calculating the first cascade (N = 1) carried transmission peak wavelength
Figure 545481DEST_PATH_IMAGE003
When k =1, the interference order is m × 2 N-1 -1=2, when the first cascade carries the transmission peak wavelengthλ 1,1 Is 600nm; when k =2, the interference order is m × 2 N-1 -2=1, when the first cascade carries the transmission peak wavelengthλ 1,2 1200nm, the visible output spectrum should have peak outputs at 400nm, 600nm and 1200nm;
s4.3: calculating the retardation of the rest of the cascade, repeating step S4.2, and in the second cascade (N = 2), the first cascade transmits the peak wavelengthλ 0 、λ 1,1 Andλ 1,2 within the cascade there is an interference maximum, the interference order of which6, 3 and 2 respectively; in the third cascade (N = 3), the first cascade transmits the peak wavelengthλ 0 、λ 1,1 Andλ 1,2 there is a maximum of interference within the cascade with interference orders of 12, 8 and 4 respectively;
therefore, the invention can realize three-passband wavelength output;
s5: adjusting the external electric signal of the liquid crystal, adjusting the voltage value applied to the outside of each level of liquid crystal through software according to the delay amount of each level of liquid crystal, driving the optical parameters of the liquid crystal to change, and finally realizing multi-passband spectral output as shown in fig. 3;
FIG. 3 is a transmittance curve of three-passband wavelength output, the main transmission peak output is accompanied by the output of the carried transmission peak, the transmittance at the transmission peak is 1, the bandwidth of the main transmission peak is 16nm, the bandwidth of the carried transmission peak 1 is 36nm, and the bandwidth of the carried transmission peak 2 is 154nm. The invention applies three cascades, can obviously reduce the number of cascades under the condition of not sacrificing the bandwidth of the main transmission peak, and effectively improves the spectrum output energy on the premise of meeting the requirement of channel switching. As can be seen from fig. 3, the multi-passband peaks output by the invention can be effectively staggered, and interband gaps for inhibiting light transmission are generated between passbands, thereby ensuring the switching requirement of communication channels. And, the main transmission wavelength bandwidth is narrowest, and the degree of the carried transmission wavelength becomes wider and wider along with the distance from the main wavelength, and the larger the spectral energy that can be transmitted.
Example 2
This example is the same as example 1, in which the number of transmission peaks m is set to 2, and the wavelength of the main transmission peak is set to 2λ 0 The number of cascade is set to 400nm, and the number of cascade is set to two;
the retardation of the liquid crystal in the first cascade (N = 1) can be obtained according to the steps of the methodδ 1 At 1000nm, k =1, the interference order is m × 2 N-1 -1=1, when the first cascade carries the transmission peak wavelengthλ 1,1 1000nm, the visible output spectrum should have peak outputs at 500nm and 1000 nm; when the retardation of the liquid crystal of the rest cascades is calculated, the following results can be obtained: in the second cascade (N = 2), there is an interference maximum at the peak wavelength, the interference order of which is subdivided into6 and 3; in the third cascade (N = 3), the first cascade transmits the peak wavelengthλ 0 Andλ 1,1 there is a maximum of interference within the cascade with interference orders of 12 and 6, respectively, from which it is seen that the invention is capable of achieving two-band wavelength output. According to the retardation of each level of liquid crystal, the voltage value applied to the outside of the liquid crystal is adjusted through software, the optical parameters of the liquid crystal are driven to change, and the multi-passband spectrum output is finally realized, as shown in fig. 4, the transmittance curve of the two-passband wavelength output shows that the multi-passband spectrum can be output, and the liquid crystal display has universality.
Example 3
The same procedure as in example 1 and example 2 was followed, in this example, the number of transmission peaks was set to 3, the main transmission peak wavelengths were set to 400nm, 420nm, and 450nm, respectively, and the number of cascades was set to three (N =1,2,3);
according to the method steps, the liquid crystal retardation delta of the first cascade (N = 1) under different main transmission peak conditions can be obtained 1 1200nm, 1260nm and 1350nm, respectively, and when k =1, the interference order is m × 2 N-1 -1=2, the wavelength of the first cascade-carried transmission peak is 400nm for the main transmission peakλ 1,1 600nm, and the wavelength of the first cascade carried transmission peak is 420nmλ 1,1 630nm, and the wavelength of the first cascade carried transmission peak when the main transmission peak is 450nmλ 1,1 At 675nm; when k =2, the interference order is m × 2 N-1 -2=1, when the main transmission peak is 400nm, the first cascade carries the transmission peak wavelengthλ 1,2 1200nm, and the wavelength of the first cascade carried transmission peak when the main transmission peak is 420nmλ 1,2 1260nm, and 450nm as main transmission peakλ 1,2 Is 1350nm; see table 1 specifically:
TABLE 1 carried transmission peaks of different main transmission peaks
Figure 775343DEST_PATH_IMAGE013
When the liquid crystal retardation of the rest cascades (N =2, 3) is calculated, the interference maximum value of the peak wavelength in each cascade can be obtained, and the specific numerical values are shown in table 2:
TABLE 2 Main Transmission stages Cascade interference stages
Figure 4199DEST_PATH_IMAGE014
According to the delay amount of each level of liquid crystal, the voltage value applied to the outside of the liquid crystal is adjusted through software, so that the optical parameters of each level of liquid crystal are driven to change, and multi-passband spectrum transmission is finally realized; as shown in fig. 5, fig. 5 is a transmittance curve diagram of a multi-passband liquid crystal tunable filter with different main transmission wavelengths, it is obvious that different main transmission peaks are accompanied by the same number of carried transmission peaks, and the carried transmission peak positions are shifted as a whole along with the change of the main transmission peak positions, so that the modulation coverage of a wide spectrum band can be realized.
Example 4
The invention also comprises an electronic device comprising a memory storing a computer program and a processor implementing the steps of any of the above methods when executing the computer program.
The invention also includes a computer readable storage medium for storing computer instructions which, when executed by a processor, implement the steps of any of the methods described above.
The memory in the embodiments of the present application may be either volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The non-volatile memory may be a Read Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), or a flash memory. Volatile memory can be Random Access Memory (RAM), which acts as external cache memory. By way of example, and not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), dynamic random access memory (dynamic RAM, DRAM), synchronous Dynamic Random Access Memory (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), SLDRAM (synchronous DRAM), and direct rambus RAM (DR RAM). It should be noted that the memories of the methods described herein are intended to comprise, without being limited to, these and any other suitable types of memories.
In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the application to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that includes one or more available media. The usable medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a Digital Video Disc (DVD)), or a semiconductor medium (e.g., a Solid State Disc (SSD)), among others.
In implementation, the steps of the above method may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The steps of the method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in a processor. The software modules may be located in ram, flash, rom, prom, or eprom, registers, etc. as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and combines hardware thereof to complete the steps of the method. To avoid repetition, it is not described in detail here.
It should be noted that the processor in the embodiments of the present application may be an integrated circuit chip having signal processing capability. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The processor described above may be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and combines hardware thereof to complete the steps of the method.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. And obvious variations or modifications derived therefrom are intended to be within the scope of the invention.

Claims (9)

1. A multi-passband liquid crystal tunable filtering method applied to laser communication is characterized by comprising the following steps:
s1: determining initial parameters, determining the number m of transmission peaks and the wavelength of main transmission peak which are separated from each other and generated simultaneously in the visible wave band and the near infrared wave bandλ 0 (may be written as
Figure 208246DEST_PATH_IMAGE001
）；
S2: setting cascade initial conditions, wherein the cascade comprises two polaroids and a liquid crystal, transmission optical axes of the two polaroids are parallel to each other, an included angle between the optical axis direction of the two polaroids and the o-ray vector direction of the liquid crystal is 45 degrees, and the single cascade light transmittance is determined according to a formula;
s3: setting N cascades with the same cascade structure as the cascade structure in the step S2, and determining the total light transmittance of the N cascades according to a formula;
s4: calculating the retardation of each cascade liquid crystal, setting the position of a main transmission peak as an interference maximum value according to an interference principle to obtain the retardation required to be introduced into each stage of cascade liquid crystal, wherein the retardation required to be introduced into each stage of cascade liquid crystal is obtained according to the following formula:
Figure 235762DEST_PATH_IMAGE002
；
s5: and adjusting the external electric signal of the liquid crystal, adjusting the voltage value applied to the outside of each cascade liquid crystal through software according to the retardation of each level of liquid crystal, and driving the optical parameters of the liquid crystal to change so as to realize multi-passband spectral output.
2. The method according to claim 1, wherein step S4 is specifically:
s4.1: will carry out the stepsNumber m of transmission peaks and main transmission peak wavelength λ determined in step S1 0 Substituting into the formula of retardation amount to calculate the retardation amount delta of the first cascade liquid crystal 1 ；
S4.2: calculating the wavelength of the first cascade carried transmission peak
Figure 87174DEST_PATH_IMAGE003
The first cascade carries the number of transmission peak wavelengths of
Figure 424615DEST_PATH_IMAGE004
According to the retardation delta obtained in step S4.1 1 Calculating the interference order of
Figure 910829DEST_PATH_IMAGE005
First cascade of time carrying transmission peak wavelength
Figure 590203DEST_PATH_IMAGE003
Wherein k is more than or equal to 1 and less than m.2 N-1 A positive integer of (a);
s4.3: calculating the retardation of the rest cascaded liquid crystals, repeating the step S4.2, calculating and judging the wavelength of the main transmission peakλ 0 And the first cascade carries the wavelength of the transmission peak
Figure 381441DEST_PATH_IMAGE003
Whether or not there is an interference maximum in the liquid crystal.
3. The method of claim 2, wherein the main transmission peak and the first cascade-carrying transmission peak are staggered with an interband gap between the main transmission peak and the first cascade-carrying transmission peak that inhibits light transmission.
4. The method of claim 2, wherein the main transmission peak wavelengthλ 0 The bandwidth is narrowest, and the first cascade carries the wavelength of the transmission peak
Figure 40349DEST_PATH_IMAGE003
Wavelength of main transmission peak with distanceλ 0 The degree is wider and the transmission energy is larger and larger.
5. The method of claim 1, wherein different main transmission peaks are accompanied by the same number of carrier transmission peaks, and the positions of the carrier transmission peaks are shifted as a whole with changes in the positions of the main transmission peaks.
6. The method of claim 2, wherein the light transmittance of the single cascade is:
Figure 866223DEST_PATH_IMAGE006
(i =1,2, \8230;), i being the number of cascade layers;
wherein the content of the first and second substances,
Figure 450919DEST_PATH_IMAGE007
is the amount of phase retardation of the liquid crystal,
Figure 463874DEST_PATH_IMAGE008
。
7. the method of claim 6, wherein the total light transmittance of the N cascades is:
Figure 657964DEST_PATH_IMAGE009
。
8. an electronic device comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of the method according to any one of claims 1-7 when executing the computer program.
9. A computer-readable storage medium storing computer instructions, which when executed by a processor, perform the steps of the method of any one of claims 1 to 7.
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